Source: UNIVERSITY OF FLORIDA submitted to NRP
LIMITING LOSSES TO BACTERIAL SPOT THROUGH KNOWLEDGE OF GLOBAL PATHOGEN DIVERSITY, IMPROVED SEED HEALTH, NOVEL BACTERICIDES & TOMATO BREEDING
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1007630
Grant No.
2015-51181-24312
Cumulative Award Amt.
$3,448,508.96
Proposal No.
2015-09343
Multistate No.
(N/A)
Project Start Date
Sep 1, 2015
Project End Date
Feb 28, 2021
Grant Year
2020
Program Code
[SCRI]- Specialty Crop Research Initiative
Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
AG-GCREC - BALM
Non Technical Summary
Fresh market and processing tomatoes are important segments of the U.S. agricultural economy with significant acreage in 16 states that grossed over $2.5 billion in 2008.Bacterial spot of tomato (BST) is a major challenge to commercial tomato production throughout the Eastern and Midwestern U.S. that threatens the long-term sustainability of the industries, due to a lack of effective control measures. A recent study estimated annual production losses in southwest FL due to BST at $3,090 per acre based on 2007-2008 production costs and market values; that equates to approximately $100 million in crop losses for Florida alone. In the Midwest, the processing industry estimated a loss of $7-8 million total due to BST in 2010.This proposal is the result of discussions with tomato grower organizations, transplant producers, crop consultants, processors and other industry representatives who have all expressed an urgent need for research to improve the management of BST. In the proposed research, we will reduce economic losses associated with BST by exploiting Xanthomonas genomics to track global and regional strain movement from seed to field to identify BST control points and identify novel Xanthomonas strains that could undermine breeding efforts (Objective 1); advance novel methodologies to reduce or eliminate seedborne Xanthomonas spp., improve seed & seedling health, and reduce subsequent transmission and spread during tomato seedling production and beyond (Objective 2); and accelerate the development and release of varieties with resistance to BST through genome assisted classical breeding strategies and CRISPR/Cas9genome-editing approaches (Objective 3). The proposed novel seed sanitation methods could revolutionize the seed industry, improving plant health and reducing the spread of seedborne pathogens.Our outreach plan (Objective 4) will develop a focused approach to understand the economic impact of BST throughout the entire tomato industry, generating cost-benefit information for the production chain that should encourage adoption and help leverage the additional costs of developed treatments among all beneficiaries. Extension products, such as articles in trade journals, fact sheets, presentations at field days, and technical meetings, will complement available information on a project-specific website, to effectively reach producers and the seed industry, as well as vegetable specialists throughout the U.S. and abroad. Project participants will work together to develop and disseminate recommendations for best management practices (BMPs) to the tomato industry.An advisory committee composed of industry stakeholders has been assembled to give annual feedback to project staff regarding progress and results of research, economics, and any deviation to the proposed objectives.Development and adoption of varieties with durable resistance to BST and BMPs will reduce the occurrence of BST outbreaks, lessen the need for costly inputs, and improve industry profits. ?
Animal Health Component
40%
Research Effort Categories
Basic
60%
Applied
40%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2121460108125%
2124010110030%
2164010117030%
6011460310015%
Knowledge Area
601 - Economics of Agricultural Production and Farm Management; 212 - Pathogens and Nematodes Affecting Plants; 216 - Integrated Pest Management Systems;

Subject Of Investigation
1460 - Tomato; 4010 - Bacteria;

Field Of Science
1081 - Breeding; 1100 - Bacteriology; 1170 - Epidemiology; 3100 - Management;
Goals / Objectives
The long-term goal of the research proposed in this Standard Research and Extension Project is to improve the management of bacterial spot of tomato from "seed to fruit", alleviating economic losses associated with the disease. Towards thisgoal we propose to reduce economic losses associated with BST by exploitingXanthomonas genomics to track global and regional strain movement, identify and introduce novelresistance genes into tomato, and accelerate the development and release of BST-resistant varieties usinggenome-assisted classical breeding strategies and Cas9/CRISPR genome-editing approaches. Furthermore, we willlimit commercial outbreaks and the introduction of exotic strains by improving seed sanitation methods,developing novel bactericides, and establishing Best Management Practices (BMPs) for the industry.Finally, wewill determine the economic impact of BST on the tomato industry, and demonstrate how BMPadoption benefits the entire industry using focus groups composed of stakeholders (seed companies,transplant operations and grower operations) to facilitate information exchange and promote industrywidestewardship of developed technologies and sources of BST resistance. Project objectives are: 1) Monitorthe global movement of tomato bacterial spot-causing Xanthomonas spp., characterize epidemiologicalpathways, and identify critical control points in the production chain from seed to final product in the U.S.;2) Advance of integrated approaches to pre-empt or mitigate outbreaks of BST-causing Xanthomonasspecies from seed to field will include methods to: reduce or eliminate seedborne Xanthomonas species;improve seed health; and develop and employ the integrated use of novel bactericides to manage BSTfrom seed through commercial field production.; 3) Implement complementary approaches for acceleratedintroduction of resistance, through genomics assisted breeding and genome editing into advance breedingmaterials.; and 4) Assess the economic impact of adopting BST management practices/technology, anddevelop Best Management Practices (BMP) for managing BST throughout the production chain.
Project Methods
Objective 1: We aim to reduce the introduction and spread of Xanthomonas strains in tomato production by identifying the source of outbreaks and origins of new strains. We will expand upon our current collaboration studying field strains by characterizing tomato Xanthomonas strains from affected production areas in the Southeastern and Midwestern U.S., and primary seed production regions in Southeast Asia and Latin America. We will use strategic sampling together with SNPs obtained from genome sequencing to trace the pathways of movement of strains from seed to field and understand whether seed production areas act as sources of new strains. These data will be used to identify critical control points in production. We will monitor for shifts in Xanthomonas populations towards bactericide resistance and increased virulence, and alert breeders to genetic variation that may impose risks to breeding efforts.Objective 2: To better understand the Xanthomonas-seed relationship, we will develop and optimize histologic and cytogenetic methods to locate Xanthomonas spp. within naturally and artificially infected tomato seeds. To insure that chemical seed treatments can eradicate Xanthomonas spp. that reside beneath the seed coat or in the embryo, we will characterize the physical/chemical properties of compounds that are able to diffuse through the seed coat to the embryo based on previously described seed coat permeability protocols. Efficacy of chemical seed treatments with emphasis on small drug-like molecules will be tested for eradication of seedborne Xanthomonas. Additionally, the efficacy of physical treatments, including UV light and enzyme-based componentsapplied prior to or with seed coating will be evaluated. As another approach, we will evaluate several promising Cu-composites that use mixed oxidative states of copper for managing BST outbreaks will be examined in transplant and field production. Coordinated research will be conducted at several research centers, transplant facilities, and commercial grower locations to test the effective use of products and ensure the safety of products throughout the production cycle. To better assess developed treatments under commercial production conditions, we will work closely with the seed industry through existing relationships to develop and evaluate sanitizing seed treatments compatible with seed processing technology, and with transplant production facilities to improve transplant quality and identify potential unforeseen issues with seed sanitation methods and bactericidal treatments. This strategy will give us an opportunity to work closely with transplant operations to assess the economic impact of BST and treatments on transplant production for Objective 4. Objective 3: Genetic resistance is among the most promising approaches to ameliorate the effects of bacterial disease. Several classically defined resistance effector-specific loci have been discovered and mapped relative to DNA-based markers. In addition, QTL that are effective against multiple races and species of Xanthomonas have been discovered and mapped.In an effort to accelerate current bacterial spot resistance breeding, efforts at the Ohio State University and the University of Florida, we will implement a complementary approach to pyramid tomato resistance and pursue genome editing to produce resistant tomato plants. Combining multiple race-specific genes for resistance with QTLs that appear effective against multiple Xanthomonas species causing BST is a major goal. Under the "conventional" phase of this objective, we will combine Rx-3, Rx-4/Xv3, with QTLs effective against a broad range of strains using genomics assisted breeding bytakingadvantage of SolCAP generated resources which include ~15 Gb of transcriptome data from normalized cDNA libraries using the Illumina GAII next generation sequencing technology.Genome editing experiments will involve altering the tomato ortholog of the bs5 recessive resistance gene from pepper, by usingCRISPR/Cas9 system to introduce to introduce an in-frame 2 leucine amino acid deletion in the C-terminus of an endogenous tomato ortholog. We further propose to homologously recombine the CcBs2 (ORF) into a precise location in the tomato genome that will exchange this open reading frame for the inactive Slbs2 ortholog. The edited locus will only contain plant DNA and will consist of the native promoter driving the expression of the CcBs2 gene. We will finally combine all resistance genes and QTL with edited genes into common genomic backgrounds, which isexpected to provide a source of durable resistance. Developed tomato lines will be assessed in field trials.Objective 4: Different seed sanitation/treatment practices will be designed and the effect on the seed infection rate will be tested and analyzed. We will obtain data from seed treatments and nursery and field trials to: 1) quantify the effect of infection/infestation level on yield and its economic impact using statistical methods, 2) analyze the cost and benefit of different BST treatments throughout the production chain to identify the best management practices (BMPs). Production costs and revenues of various treatments will be calculated, and the partial budgeting method will be used to analyze the cost and benefit of different treatments.The economic analysis will further incorporate risk factors to account for bacterial spot incidence and damages. We will determine BST incidence and severity from trials conducted in LA (small scale production) and OH & FL (large scale production) and from historical industry/growers data. Simetar, a risk and return analysis software developed by Texas A&M University, will be used to model the return and risk associated with bacterial spot.We will also develop a model to analyze the dynamics of bacterial spread of Xanthomonas strains over time and space and within the constraints of the investigated control strategies. The model will then be used to identify an optimal control strategy at each sector (or point) that makes up the most cost effective BST management practice(s) for the entire production chain from seed to final product.Using a modified Theory of Planned Behavior (TPB)approach, grower and industry behavioral, normative and control beliefs pertaining to the use of seed sanitizers and alternatives to streptomycin and copper will be assessed. Focus groups of transplant/tomato growers will be held in two tomato production areas in the southern US and will represent small and large-scale production locations. Once accessible beliefs have been identified, participants in the focus group will be asked to complete a questionnaire that will include direct quantitative measures of adoption attitudes, subjective norms, perceptions of behavioral control, intentions, and actual behavior. Results of all objectives will be used to establish Best Management Practices (BMPs). BMPs will be promoted by integrating different modes of communication and levels of knowledge similar to the electronic media we have previously produced (www.vegetablediseasefacts.com; www.edis.ifas.ufl.edu).

Progress 09/01/15 to 02/28/21

Outputs
Target Audience:Target audience during this project included commercial vegetable growers, transplant operations, vegetable packing house operations, seed company representatives, county extension agents, and researchers in plant pathology, plant-microbe interactions, and plant breeding. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? A visiting scientist, Associate Professor Dr. D. Yang from the Institute of Plant Protection, Chinese Academy of Agriculture Science, Beijing enhanced his analytical skills working on the project with Dr. Alan Taylor. A visiting scientist, Assistant Professor Dr. X. Yan from the Institute of Plant Protection, Chinese Academy of Agriculture Science enhanced her professional skills working on the project with Dr. Hilary Mayton. Rotondo F., Amrhein, J., Vargas, A., Miller S.A. Plant Health 2020, APS Annual Meeting (virtual). Rotondo F. Saint-Preux C., Miller S.A., Lewis Ivey M.L. 35th Tomato Disease Workshop, Univ. California ANR, 2020 (virtual). Rotondo F., Bernal E., Miller S.A. Plant Health 2019, APS annual Meeting, Cleveland, OH, USA. Rotondo F., Miller S.A. 34th Tomato Disease Workshop, 2019, Clearwater, FL, USA. Rotondo F., Miller S.A. 33rd Tomato Disease Workshop, 2018, Chincoteague, VA, USA. Rotondo F., Moodispaw M., Sally Miller 32nd Tomato Disease Workshop, 2017, Tampa, FL, USA. How have the results been disseminated to communities of interest?Presentations to growers and other groups/outreach Klein-Gordon, J., P. Abrahamian, S. Timilsina, G.V. Minsavage, J.B. Jones, G.E. Vallad, E.M. Goss. 2019. Recent state-wide survey reveals continued shifts in Xanthomonas populations in Florida commercial tomato fields. University of Florida, Emerging Pathogens Institute, Research Day, Gainesville, FL. *Rotondo F., Miller S.A. Biopesticides to control spot, canker in greenhouse transplants, MID-ATLANTIC Fruit & Vegetable Convention, January 28, 2020, Hershey, PA, USA. *Miller, S. A. Managing bacterial diseases of vegetables. Salem Produce Growers Meeting, February 25, 2020, Columbiana, OH. *Miller, S. A. Integrated approaches to managing bacterial diseases of tomatoes. Ontario Fruit and Vegetable Conference, Niagara Falls, Ontario, Canada, February 20, 2019. *Miller, S. A. and Rotondo, F. Managing bacterial spot in tomatoes. Mid-Atlantic Fruit and Vegetable Convention, Hershey, PA, January 29-30, 2019. *Miller, S. A. Managing bacterial diseases of vegetables. Mid-Ohio Growers Meeting, Mt. Hope, OH, January 12, 2018. *Francis, David. 2020. Pathogen Populations as a Moving Target. 2020 Indiana Horticultural Congress Feb. 11-13, 2020, Indianapolis, IN. *Vallad, G.E. 2019. Integrated approaches to bacterial spot management for tomatoes - A Florida perspective. VII Simposio Nacional y VI Internacional de Bacterias Fitopatógenas y III Simposio de bacterias benéficas de las plantas, Guadalajara, Jalisco, Mexico. (oral presentation) *Vallad, G.E. 2019. Movement and management of tomato bacterial spot during seedling production. Ontario Tomato Seedling Growers Meeting, University of Guelph, Ridgetown, Ontario, Canada. (oral presentation) *Abrahamian, P.p and G.E. Vallad. 2018. Bacterial spot and target spot update. Lipman Grower Retreat, hosted by Lipman Produce, Immokalee, FL. (oral presentation) *Vallad, G.E. 2018. Movement and management of tomato bacterial spot during seedling production. 34th Annual UF/IFAS Florida Seed Association, Gainesville, FL. (oral presentation) *Vallad, G.E. 2018. Integrated approaches to disease management for tomatoes - A Florida perspective. 1st HZAU-UF Bi University Symposium, Huazhong Agricultural University, Wuhan, China. (oral presentation) *Vallad, G.E. 2018. Integrated approaches to disease management for tomatoes - A Florida perspective. Department of Plant Pathology, China Agricultural University, Beijing, China. (oral presentation) *Vallad, G.E. 2017. From seed to fork: Advancing integrated practices for managing tomato bacterial spot. The 2017 Florida Tomato Institute, Naples, FL. (oral presentation) *Vallad, G.E. 2017. A synopsis of soilborne pests and diseases, and the status of proposed IPM strategies for Florida's small fruit and vegetable industry. 2017 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions, San Diego, CA (oral presentation) *Vallad, G.E. 2017. Integrated bacterial spot management, a Florida perspective... The 49th Annual Meeting of the NC Tomato Growers Association, Asheville, NC. (oral presentation) *Vallad, G.E. 2017. Current management options for bacterial spot on tomato (and Pepper). 2017 Southeast Regional Fruit & Vegetable Conference. Savannah, GA. (oral presentation) *Vallad, G.E. 2017. Integrated bacterial spot management, a Florida perspective. 2017 Great Lakes EXPO, Grand Rapids, MI (oral presentation) *Vallad, G.E. 2016. The impact of bacterial spot on the commercial tomato industry in Florida. Plant Pathology Seminar, Khon Kaen University, Khon Kaen, Thailand. (oral presentation) *Vallad, G.E., P. Abrahamiang, S. Timilsinag, N. Potnis, J.B. Jones, and E. Goss. 2016. From seed to fork: Advancing integrated practices for managing tomato bacterial spot. 32nd Annual UF/IFAS Florida Seed Association, Naples, FL. (oral presentation) Vallad, G.E. 2019. Common tomato diseases of Florida. Lake County Master Gardener's Training Meeting. Tavares, FL. (oral presentation) Vallad, G.E. 2018. Common tomato diseases of Florida. Sumter County Master Gardener's Training Meeting. Bushnell, FL. (oral presentation) Vallad, G.E. 2018. Spring Vegetable Disease Update. 2018 Manatee County Spring Vegetable Industry Update, Ellenton, FL. (oral presentation) Vallad, G. E. 2017. Research matters: GCREC vegetable pathology program. UF/IFAS Gulf Coast Research and Education Center Seminar Series, Balm, FL. (oral presentation) Blogs Miller, S. A. Ohio Veggie Disease News. Bacterial disease management in vegetable crops without copper? July 18, 2020. http://u.osu.edu/miller.769/. INTERNATIONAL EFFORTS: 2019 Visited small fruit and vegetable production areas in Jalisco, Mexico to develop collaborative efforts with researchers from the University of Guadalajara. 3 days Mexico 2018 Visited researchers and made presentations at Huazhong Agricultural University in Wuhan and at China Agricultural University. 8 days China 2017 Hosted by Dr. Marlene Rosales V., visited tomato production areas, isolated bacterial pathogens and worked with graduate students at Pontificia Universidad Católica de Chile. 14 days Chile 2016 Hosted by Dr. Petcharat Thummabenjapone, visited commercial tomato seed production fields, isolated bacterial pathogens, taught graduate students, and gave a presentation at Khon Kaen University. 14 days Thailand What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Obj 1: Obtained Xanthomonas strains outside the US, examined genetic variation in 270 X. perforans (Xp) strains and 60 X. gardneri (Xg) strains from 13 countries. Identified genomic groups using nucleotide variation in core genes shared among all strains; Identified and compared Type III effectors. Collected over 700 strains in Midwest to determine distribution of Xanthomonas species among counties and seed sources. Examined role of transplants in BST outbreaks; and evaluated role of the horizontally acquired effector XopJ2 to Xp fitness. Used variation among 585 Xp strains from 70 tomato fields in FL and GA to relate production chain variables to genomic variation. Outcomes and impacts: Comparative genomics improved understanding of Xanthomonas taxonomy. Results suggest at least one Xp group recently introduced from foreign seed production areas into the US. Some Xp groups absent from US, suggesting measures needed to limit more introductions. Based on core genes, identified 6 Xp groups in FL and GA; copper (Cu) tolerance dominated with streptomycin resistance predominant in a single Xp group. Horizontal gene transfer plays a critical role in driving Xp diversity, whereas Xg is clonal. XopJ2 improved Xp ability to spread under field conditions, explaining changes in Xp populations in southeast including Xp expansion in the eastern US and Great Lakes region. Aerosolization and a 5-7 day incubation period facilitated rapid Xp movement in transplant facilities, undermining control efforts. Removal of 1 to 3 meters of asymptomatic seedlings around BST outbreaks necessary to limit pathogen spread. Epidemiological studies demonstrated transplants role in the introduction of Xp to fields. Xp populations in two fields were distinct. However, 60 and 100% of the strains from field outbreaks resembled those found earlier on transplants. Another study found evidence that farms that outsourced transplant production were associated with more diverse Xp populations than those farms that produced their own transplants. Results indicate the possible existence of other inoculum sources. Obj 2: Developed GFP- and bioluminescent-tagged Xp and Xg strains to monitor fruit and seed infection. Utilized coumarin tracers and a series of n-alkyl piperonyl amides to characterize the chemical properties (lipophilicity) needed to deliver antibacterial compounds into tomato seed. Utilized HPLC to measure tracer uptake in tomato seed and seed coat permeability in relation to lipophilicity to better elucidate compound movement in seed tissue. Conducted high-throughput screening of 4,182 small molecules for bactericidal activity against Xg (n=68), Xp (n=55), Xe (n=32), and Xv (n=4) strains in lab assays; and ideal candidates in greenhouse assays. Evaluated nanoparticle (NP) materials of silver (AgNP), magnesium oxide (MgONP), and 3 NP formulated Cu materials for BST management in seed, seedling, and field trials. Tested commercially available Cu-alternatives for BST management in transplant and field trials. Outcomes and impacts: Flower inoculations with transformed strains caused high levels of aborted flowers but no infected fruit or seed. Fruit inoculated shortly after self-pollination led to infections. Bioluminescent Xg observed 6 days post-inoculation (DPI) in fruits <2 cm diameter. Internal colonization of fruit observed within 42 DPI, including seed cavity colonization. Bioluminescent signals mainly found in fruit exocarp, signals sometimes observed in the mesocarp and endocarp. On artificially infested seeds, Xp & Xg recovery declined with time; Xp persisted longer than Xg, but strain-to-strain variability detected in both species. Infested seed levels influenced seedling disease incidence and resulting severity. PCR with hrpB7 primers confirmed Xv presence on naturally infested seed and germinated seedlings, but seed to seedling transmission negligible under controlled conditions. Findings do not exclude seed as a source of BST outbreaks, but suggest seed infection is limited and may vary with strains. Use of coumarin tracers and amide series demonstrated uptake into the seedcoat required compounds with low lipophilicity, while higher higher lipophilicity is required for uptake into embryonic tissues. Even with optimal lipophilicity for embryo uptake, maximum recovery in embryonic tissue limited to only 1.2 to 5%, suggesting that any compounds applied as seed treatments would result in suboptimal concentrations in the embryo. Identified several small molecules with favorable bactericidal activity against diverse Xanthomonas in lab and seedling assays. Three small molecules showed promising activity against Xanthomonas strains on artificially infested seed reducing populations 3.4-log without impacting germination. CuNPs and MgONP effective against Xp and Xg in seed and seedling applications. NPs reduced disease severity in the field but did not improve yields. Although CuNPs still use Cu, their efficacy against Cu tolerant Xp strains uses a fraction of the Cu present in current products. Acibenzolar-S-methyl & Cu octanoate consistently reduced BST compared to traditional Cu products and streptomycin in transplant trials. The efficacy of commercially available Cu alternatives varied in field trials, none of the treatments statistically improved tomato yields. The development of effective bactericides should improve tomato health, reduce the introduction of disease inoculum into fields, and reduce industry reliance on ineffective Cu bactericides. Obj 3: Investigated BST resistance from PI114490 in 2 fresh market (FM) inbred backgrounds. Characterized non-blighting (NB) resistance in FM germplasm in Florida in separate trials against fungal and bacterial pathogens and included integrated management approaches. Identified chromosomal position(s) for Xg resistance from LA2533. Conducted CRISPR-Cas9 editing to modify the tomato ortholog of the recessive pepper CaBs5 gene (SlBs5 gene) to confer BST resistance, as well as a CaBs5-like paralog (SlBs5-like) that shares a promoter region in pepper but has not been associated with BST resistance. Outcomes and impacts: Developed Genomic Selection (GS) models that incorporate genetic information such as map position and dominance increase accuracy and relative efficiency of selection. These GS models equaled or exceeded phenotype-based selection (Liabeuf, et al., 2018). Developed processing germplasm with multiple major resistance loci (Rx-3 and Rx-4/Xv3) combined with different sources of QTL11. Confirmed that QTL11A from Hawaii 7998 was most effective, followed by QTL11B from LA2533 (Bernal, 2020). Developed FM germplasm combining Rx-3 and Rx-4/Xv3 together with QTL11A in backgrounds possessing NB trait and containing a reduced I-3 introgression that broke linkage to increased BST susceptibility (Chitwood-Brown et al., 2021). Developed SlBs5/SlBs5-like Cas9-edited FM tomato lines exhibiting reduced susceptibility to Xp (Race 4) in trials conducted in Florida, demonstrated the effective use of CRISPR-Cas9 to modify orthologous tomato genes that confer BST resistance in other Solanaceae. Obj 4: Evaluate BST impact on tomato yields caused by Xp and Xg in Ohio and Florida, respectively, and cost effectiveness of field treatments in large-plot trials. Disseminated research findings and BMPs to stakeholders and the professional community through meetings, research, and extension publications. Outcomes and impacts: High levels of BST severity, induced by repeated inoculations of plots, statistically reduced marketable yields by 30%, compared to non-inoculated plots across separate trials, while plots inoculated once reduced marketable yields by 16%. Regardless of efficacy, chemical control had little impact on marketable yields, demonstrating importance of limiting inoculum and deploying host resistance for management.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Jibrin, M, N Potnis, S Timilsina, GV Minsavage, VM Shutt, TA Coutinho, OP Pruvost, MI Siri, MJ Pianzzola, AM Quezado Duval, EV Nikolaeva, DS Egel, T Creswell, GE Ruhl, L Maynard, P Gulig, GE Vallad, PD Roberts, EM Goss, JB Jones. 2019. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Jibrin, M, N Potnis, S Timilsina, GV Minsavage Jr, E Osdaghi, S Vou, TA Coutinho, OP Pruvost, R Roach, MI Siri, MJ Pianzzola, AM Quezado Duval, DS Egel, TC Creswell, GE Ruhl, L Maynard, GE Vallad, PD Roberts, EM Goss, JB Jones. 2018. A Global Outlook on the Evolution of Type Three Effectors in Xanthomonads causing Bacterial Spot on Tomato and Pepper. International Congress of Plant Pathology (ICPP) 2018: Plant Health in A Global Economy, Boston, MA, USA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Klein-Gordon, J. 2019. More strains, more insights: Understanding the Xanthomonas perforans population across Florida commercial tomato fields via a recent state-wide survey. 2019 Florida Phytopathological Society, Lake Alfred, FL.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Klein, J, P Abrahamian, Y Xing, J Fulton, GV Minsavage, S Timilsina, ML Paret, KA Garrett, JB Jones, EM Goss, and GE Vallad. 2019. Its complicated: The Xanthomonas perforans population across Florida commercial tomato fields. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Klein-Gordon, J., J.B. Jones, G.E. Vallad, and E.M. Goss. 2018. Assessing changes in Xanthomonas perforans populations in Florida based on a recent state-wide survey of commercial tomato fields: A work in progress. Proceedings from the 2018 Florida Tomato Institute, Naples, FL.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Klein-Gordon, J.M., S. Timilsina, P. Abrahamian, G.V. Minsavage, N. Potnis, J.B. Jones, G.E. Vallad, and E.M. Goss. 2017. Whole genome sequences reveal polymorphisms in bacteriocin genes of Xanthomonas perforans in Florida. 2017 Annual Meeting of the American Phytopathological Society, San Antonio, TX.
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Kumar, L.M., S.F. Hutton and G. Vallad. 2016. Demarcation of genomic regions influencing the non-blighting trait in tomatoes. HortScience 51(9):S192. (Abstr.)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Kunwar, S, FB Iriarte, Q Fan, E da Silva, L Ritchie, N Nguyen, JH Freeman, RE Stall, JB Jones, GV Minsavage Jr, J Colee, C Zipfel, DM Horvath, J Westwood, JW Scott, GE Vallad, S Hutton, M Paret. 2018. Co-expression of Bs2 and EFR Genes in Tomato Provides Effective Broad-spectrum Field Resistance Against Bacterial Wilt and Bacterial Spot of Tomato. International Congress of Plant Pathology (ICPP) 2018: Plant Health in A Global Economy, Boston, MA, USA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Liao, Y-Y, AL Strayer-Scherer, Z Huang, S Santra, JC White, A Mukherjee, R De La Torre-Roche, Q Fan, S Wright, L Ritchie, J Colee, GE Vallad, JH Freeman, JB Jones, ML Paret. 2019. A novel alternative to copper bactericide: Magnesium nano-materials for management of bacterial spot disease of tomato. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Liao, Y-Y, AL Strayer-Scherer, Z Huang, S Santra, JC White, R De La Torre-Roche, Q Fan, S Da Silva, GE Vallad, JH Freeman, JB Jones, and ML Paret. 2019. The efficacy of MgO bactericide against bacterial spot disease of tomato is particle size-dependent. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Mayton, H., Yan, X., Amirkhani, M., Taylor, A. G. 2018. Seed germination and transmission of bacterial leaf spot in tomato seed infested with Xanthomonas. 33rd Annual Tomato Disease Workshop. October 24-26th, Chnicoteague Island, VA
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Mayton, H., Yan, X., Amirkhani, M., Taylor, A. G. 2018. Investigation of Xanthomonas euvesicatoria on seed germination and seed to seedling transmission in tomato. 20th International Conference on Seed and Crop Protection, October 29-30, Barcelona, Spain
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Paret, M.L., Y.-Y. Liao, A. Strayer, J. Freeman, J.B. Jones, and G.E. Vallad. 2018. Field performance of nano magnesium oxide, a new antibacterial compound against bacterial spot of tomato. Proceedings from the 2018 Florida Tomato Institute, Naples, FL.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Paret, ML, AL Strayer, Y-Y Liao, S Wright, M Young, I Ocsoy, D Averett, GE Vallad, S Santra, W Tan, JB Jones, SM Olson, JH Freeman. 2018. Development and evaluation of nano-materials for management of copper-tolerant Xanthomonas perforans causing bacterial spot of tomato. International Congress of Plant Pathology (ICPP) 2018: Plant Health in A Global Economy, Boston, MA, USA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Rotondo F., Bernal E., Francis D.M, Miller S.A. 2020. Antibiotic and copper resistance in plant pathogenic bacteria  Xanthomonas spp. causing bacterial leaf spot on tomato. OSU Global One Health Day Conference, November 5-7, 2020. Virtual poster.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Rotondo F. Saint-Preux C., Miller S.A., Lewis Ivey M.L. 2020. Assessing the survival of Xanthomonas gardneri and Xanthomonas perforans on artificially infested tomato seeds. 35th Tomato Disease Workshop, UC ANR.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rotondo, F, E Bernal, DM Francis, SA Miller. 2019. Distribution and Characteristics of Xanthomonas Species Causing Bacterial Spot in Midwestern Processing Tomatoes. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rotondo, F., Bernal, E., Francis, D. M. and Miller, S. A. 2019. Distribution and characteristics of Xanthomonas species causing bacterial spot in Midwest processing tomatoes. Phytopathology 109:S2.13.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rotondo, F., Bernal, E., Francis, D. M. and Miller, S. A. 2019. Distribution and characteristics of Xanthomonas species causing bacterial spot in Midwest processing tomatoes. OSU CFAES Annual Conference, Columbus, OH, April 22, 2019 (poster).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Rotondo, F. and Miller, S. A. Distribution and characteristics of Xanthomonas species causing bacterial spot in Midwestern processing tomatoes. 33rd Annual Tomato Disease Workshop, October 24-26, 2018, Chincoteague Island, VA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Rotondo, F., Moodispaw, M. R. and Miller, S. A. 2017. Tracking Xanthomonas gardneri infection of tomato fruits using an in vivo imaging system. 32nd Annual Tomato Disease Workshop, October 24, 2017, Tampa, FL. Poster.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Saint-Preux, C, SA Miller, ML Ivey 2019. Assessment of the Relationship Between Bacteria Leaf Spot Severity and Crop Yield of Fresh Market and Processing Tomato. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Liao, Y-Y, AL Strayer, Z Huang, S Santra, JC White, A Mukherjee, R De La Torre-Roche, L Ritchie, J Colee, GE Vallad, JH Freeman, JB Jones, ML Paret. 2018. A novel alternative to copper bactericide: Magnesium based nanomaterials for management of tomato bacterial spot. International Congress of Plant Pathology (ICPP) 2018: Plant Health in A Global Economy, Boston, MA, USA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Sharma, A, S Timilsina, P Abrahamian, PS Ojiambo, J Colee, GV Minsavage, GE Vallad, EM Goss, and JB Jones. 2019. Role of avrBsT in dispersal of Xanthomonas perforans and severity of bacterial spot of tomato. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Srivastava, V, L Deblais, D Kathayat, Y Helmy, SA Miller, G Rajashekara. 2019. Discovery of small molecule growth inhibitors to control bacterial leaf spot (BLS) disease of tomato. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Srivastava, V., Deblais, L., Kathayat, D., Helmy, Y., Miller, S. A. and Rajashekara, G. 2019. Discovery of small molecule growth inhibitors to control bacterial leaf spot (BLS) disease of tomato. Phytopathology 109:S2.65.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Srivastava, V., Deblais, L., Miller, S. A. and Rajashekara, G. 2018. Control of bacterial spot caused by Xanthomonas species in tomatoes using novel small molecule growth inhibitors. OARDC Annual Research Conference. April 20, The Ohio State University, Wooster, Ohio State, USA. 2018.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Srivastava, V., Deblais, L., Miller, S. A. and Rajashekara, G. 2019. Control of bacterial leaf spot (BLS) disease of tomato using novel small molecule growth inhibitors The College of Food, Agriculture, and Environmental Sciences Annual Research Conference, Ohio State University Columbus, USA, April 2019.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Timilsina, S, GP Cavalcante, R Ram�rez, MDS Bezerra de Araujo, J Tian, GV Minsavage, EM Goss, GE Vallad, JB Jones, and N Potnis. 2019. The effect of XopQ and XopJ4 on host specificity varies with the Xanthomonas perforans genetic background. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Timilsina, S, J Pereira, GV Minsavage Jr, P Abrahamian, F Iruegas-Bocardo, JC Huguet-Tapia, E Newberry, N Potnis, GE Vallad, EM Goss, JB Jones. 2018. Whole genome sequence analysis of Xanthomonas perforans shows widespread recombination events. International Congress of Plant Pathology (ICPP) 2018: Plant Health in A Global Economy, Boston, MA, USA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Timilsina, S., P. Abrahamian, N. Potnis, G.V. Minsavage, F. Iruegas, J. Klein, F.F. White, B.J. Staskawicz, J.B. Jones, G.E. Vallad, E.M. Goss. 2017. Whole genome sequencing reveals rapid shifts in tomato bacterial spot populations in Florida. University of Florida, Emerging Pathogens Institute, Research Day, Gainesville, FL.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Timilsina, S., G.E. Vallad, E.M. Goss, and J.B. Jones. 2017. Whole genome sequencing of Xanthomonas perforans strains provides insights into bacterial evolution. 2017 Florida Phytopathological Society, Gainesville, FL.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Timilsina, S., P. Abrahamian, F. Iruegas, G.V. Minsavage, B. Kolaczkowki, F.F. White, B.J. Staskawicz, G.E. Vallad, E.M. Goss, and J.B. Jones. 2017. Genomic fingerprinting and phylogenetic analyses of Xanthomonas perforans strains provide insights into bacterial evolution and global movement. 2017 Annual Meeting of the American Phytopathological Society, San Antonio, TX.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Abrahamian, P., J.M. Klein, J.B. Jones, G.E. Vallad, and R.A. Melanson. 2019. First report of bacterial spot of tomato caused by Xanthomonas perforans in Mississippi. Plant Disease 103:147.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Yang, D., Mayton, H., Amirkhani, M., and Taylor, A. G. 2017. Compound lipophilicity and implications for seed treatment efficacy. 32nd Annual Tomato Disease Workshop. October 23-25th, University of Florida/IFAS Gulf Coast research Center.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Abrahamian, P., J.B. Jones, G.E. Vallad. 2019. Efficacy of copper and copper alternatives for management of bacterial spot on tomato under transplant and field production. Crop Protection 126:104919.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Abrahamian, P., S. Timilsina, G.V. Minsavage, N. Potnis, J.B. Jones, E.M. Goss, and G.E. Vallad. 2019. Molecular epidemiology of Xanthomonas perforans outbreaks in tomato plants from transplant to field as determined by singlenucleotide polymorphism analysis. Appl Environ Microbiol 85:e01220-19.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2021 Citation: Bernal, E, Francis, DM, 2021. Processing tomato germplasm with improved resistance to bacterial spot. HortScience, DOI: https://doi.org/10.21273/HORTSCI15616-20
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Bernal, E, Liabeuf, D, Francis, DM. 2020. Evaluating quantitative trait locus resistance in tomato to multiple Xanthomonas spp. Plant Disease, 104(2):423-429.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Huang, C-H and GE Vallad. 2018. Soil applications of acibenzolar-S-methyl induce defense gene expression in tomato plants against bacterial spot. European Journal of Plant Pathology 150:971-981.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Jibrin, MO, N Potnis, S Timilsina, GV Minsavage, GE Vallad, PD Roberts, JB Jones, and EM Goss. 2018. Genomic inference of recombination-mediated evolution in Xanthomonas euvesicatoria and X. perforans. Appl Environ Microbiol 84:e00136-18.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Kunwar, S., F. Iriarte, Q. Fan, E.E. da Silva, L. Ritchie, N.S. Nguyen, J.H. Freeman, R.E. Stall, J.B. Jones, G.V. Minsavage, J. Colee, J.W. Scott, G.E. Vallad, C. Zipfel, D. Horvath, J. Westwood, S.F. Hutton, and M.L. Paret. 2018. Transgenic Expression of EFR and Bs2 Genes for Field Management of Bacterial Wilt and Bacterial Spot of Tomato. Phytopathology 108:1402-1411.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2021 Citation: Klein-Gordon, J., Y. Xing, K.A. Garrett, P. Abrahamian, M.L. Paret, G.V. Minsavage, A.L. Strayer-Scherer, J. Fulton, S. Timilsina, J.B. Jones, E.M. Goss, and G.E. Vallad. 2021. Assessing changes and associations in the Xanthomonas perforans population across Florida commercial tomato fields via a state-wide survey. Phytoplathology. https://doi.org/10.1094/PHYTO-09-20-0402-R
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Liabeuf, D, SC Sim, DM Francis. 2018. Comparison of marker-based genomic estimated breeding values and phenotypic evaluation for selection of bacterial spot resistance in tomato. Phytopathology, 108 (3), 392-401
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Liao, Y.Y., A. Strayer-Scherer, J.C. White, R. De La Torre-Roche, L. Ritchie, J. Colee, G.E. Vallad, J. Freeman, J.B. Jones, and M.L. Paret. 2019. Particle-size dependent bactericidal activity of magnesium oxide against Xanthomonas perforans and bacterial spot of tomato. Sci Rep 9, 18530
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Liao, Y.-Y., A.L. Strayer-Scherer, J. White, A. Mukherjee, R. De La Torree-Roche, L. Ritchie, J. Colee, G.E. Vallad, J.H. Freeman, J.B. Jones, and M.L. Paret. 2019. Nano-Magnesium Oxide: A Novel Bactericide Against Copper-Tolerant Xanthomonas perforans Causing Tomato Bacterial Spot. Phytopathology 1:52-62.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Mayton, H.; Amirkhani, M.; Yang, D.; Donovan, S.; Taylor, A.G. 2021. Tomato Seed Coat Permeability: Optimal Seed Treatment Chemical Properties for Targeting the Embryo with Implications for Internal Seed-Borne Pathogen Control. Agriculture 2021, 11, 199
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2021 Citation: Sharma, A., S. Timilsina, P. Abrahamian, G.V. Minsavage, J. Colee, P.S. Ojiambo, E.M. Goss, G.E. Vallad, and J.B. Jones. 2021. Need for speed: Bacterial effector XopJ2 is associated with increased of dispersal velocity of Xanthomonas perforans. Environmental Microbiology https://doi.org/10.1111/1462-2920.15541
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Sim, S-C., Robbins, M., Wijeratne, S., Wang, H., Yang, W., Francis, D.M. 2015. Association Analysis for Bacterial Spot Resistance in a Directionally Selected Complex Breeding Population of Tomato. Phytopathology, 105 (11), 1437-1445.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2021 Citation: Srivastava V., Deblais L., Kathayat D., Rotondo F., Helmy YA., Miller SA., and Rajashekara G. (2021). Novel small molecule growth inhibitors of Xanthomonas spp. causing bacterial spot of tomato. Phytopathology 111 (in press).
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2021 Citation: Chitwood-Brown, J., G.E. Vallad, and S.F. Hutton. 2021. Characterization and elimination of linkage-drag associated with Fusarium wilt race 3 resistance genes. Theor. Appl. Genet. https://doi.org/10.1007/s00122-021-03810-5
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Strayer-Scherer, A, YY Liao, M Young, L Ritchie, GE Vallad, S Santra, JH Freeman, D Clark, JB Jones, ML Paret. 2018. Advanced Copper Composites Against Copper-Tolerant Xanthomonas perforans and Tomato Bacterial Spot. Phytopathology 108:196-205.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Timilsina, S, H Adkison, AL Testen, EA Newberry, SA Miller, ML Paret, GV Minsavage, EM Goss, JB Jones, and GE Vallad. 2017. A Novel Phylogroup of Pseudomonas cichorii Identified Following an Unusual Disease Outbreak on Tomato. Phytopathology 107:1298-1304.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Timilsina, T., J.A. Pereira-Martin, G.V. Minsavage, F. Iruegas-Bocardo, P. Abrahamian, N. Potnis, B. Kolaczkowski, G.E. Vallad, E.M. Goss, and J.B. Jones. 2019. Multiple recombination events drive the current genetic structure of Xanthomonas perforans in Florida. Frontiers in Microbiology 10:448
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Timilsina, S., S. Kara, M.A. Jacques, N. Potnis, G.V. Minsavage, G.E. Vallad, J.B. Jones, M. Fischer-Le Saux. 2019. Reclassification of Xanthomonas gardneri (ex `uti? 1957) Jones et al. 2006 as a later heterotypic synonym of Xanthomonas cynarae Tr�baol et al. 2000 and description of X. cynarae pv. cynarae and X. cynarae pv. gardneri based on whole genome analyses. Int J Syst Evol Microbiol 69:343349
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Timilsina, S, GV Minsavage, J Preston, EA Newberry, ML Paret, EM Goss, JB Jones, and GE Vallad. 2018. Pseudomonas floridensis sp. nov., a bacterial pathogen isolated from tomato. International Journal of Systematic and Evolutionary Microbiology 68:64-70.
  • Type: Other Status: Published Year Published: 2019 Citation: Strayer-Scherer, A., Liao, Y.-Y., Abrahamian, P., Timilsina, S., Paret, M., Momol, T., Jones, J., & Vallad, G. (2019). [PP353] Integrated Management of Bacterial Spot on Tomato in Florida. EDIS, 2019(6), https://journals.flvc.org/edis/article/view/108765
  • Type: Other Status: Published Year Published: 2019 Citation: Vallad, G.E. 2019. Getting the jump on tomato bacterial spot begins with transplant health! Vegetable and Specialty Crop News. June 2019.
  • Type: Other Status: Published Year Published: 2018 Citation: Abrahamian, P. and Vallad, G.E. 2018. Clean tomato transplants: The first line of defense against bacterial spot. Berry/Vegetable Times. University of Florida, IFAS Extension. Summer 2018.
  • Type: Other Status: Published Year Published: 2017 Citation: Abrahamian, P., G. E. Vallad, R. Willis, H. Adkison, A. Wen. 2017. Evaluation of copper and biological compounds for managing bacterial spot of tomato, fall 2016. Plant Disease Management Reports 11:V016.
  • Type: Other Status: Published Year Published: 2017 Citation: Abrahamian, P., G. E. Vallad, R. Willis, H. Adkison, A. Wen. 2017. Evaluation of copper and non-copper alternative compounds for managing bacterial spot of tomato, fall 2016. Plant Disease Management Reports 11:V085.
  • Type: Other Status: Published Year Published: 2021 Citation: Miller, S.A., Vargas, A. and Amrhein, J. 2021. Evaluation of biological and chemical products for the control of bacterial spot of processing tomatoes, 2020.
  • Type: Other Status: Published Year Published: 2019 Citation: Miller, S. A., Mera, J. R. and Anderson, J. P. 2019. Evaluation of fungicides and bactericides for the control of bacterial leaf spot of processing tomatoes, 2018. Plant Disease Management Reports 13:V036.
  • Type: Other Status: Published Year Published: 2017 Citation: Miller, S. A., Mera, J. R., Saint-Preux, C. and Rotondo, F. 2017. Evaluation of fungicides and bactericides for the control of bacterial leaf spot of processing tomatoes, 2016. Plant Disease Management Reports 11:V113
  • Type: Theses/Dissertations Status: Published Year Published: 2017 Citation: Abrahamian, Peter. 2017. Fitness, molecular characterization and management of bacterial leaf spot in tomatoes. Doctoral dissertation, University of Florida. https://etd.uflib.ufl.edu.
  • Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Bernal, Eduardo. 2020. Characterization of Xanthomonas spp. causing bacterial spot and the development of disease resistant tomato lines (S. lycopersicum). Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University. Electronic Thesis or Dissertation. Ohio State University, 2020. https://etd.ohiolink.edu.
  • Type: Theses/Dissertations Status: Awaiting Publication Year Published: 2021 Citation: Bocardo, Fernanda Iruegas. 2021. Population genomics of Xanthomonas euvesicatoria and X. perforans: effector distribution within an evolutionary context. Doctoral dissertation, University of Florida. https://etd.uflib.ufl.edu.
  • Type: Theses/Dissertations Status: Published Year Published: 2016 Citation: Kara, Serhat. 2016. Characterization of a new type three secretion effector in Xanthomonas cynarae. Masters thesis, University of Florida. https://etd.uflib.ufl.edu.
  • Type: Theses/Dissertations Status: Awaiting Publication Year Published: 2020 Citation: Klein-Gordon, Jeannie. 2020. Xanthomonas perforans: population shifts over time in Florida and exploration of a secret weapon for keeping its competitors at bay. Doctoral dissertation, University of Florida. https://etd.uflib.ufl.edu.
  • Type: Theses/Dissertations Status: Awaiting Publication Year Published: 2021 Citation: Sharma, Anuj. 2021. Epidemiological, genomic, and transcriptomic study of xanthomonads associated with tomato, pepper, and citrus. Doctoral dissertation, University of Florida. https://etd.uflib.ufl.edu.
  • Type: Theses/Dissertations Status: Published Year Published: 2017 Citation: Strayer-Scherer, Amanda Lynne. 2017. Novel approaches for the diagnosis and management of bacterial spot of tomato. Doctoral dissertation, University of Florida. https://etd.uflib.ufl.edu.
  • Type: Theses/Dissertations Status: Published Year Published: 2016 Citation: Timilsina, Sujan. 2016. Pseudomonas characterization and population studies of Xanthomonas from Florida. Doctoral dissertation, University of Florida. https://etd.uflib.ufl.edu.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Abrahamian, P., S. Timilsina, G. V. Minsavage, E. Goss, J.B. Jones, G.E. Vallad. 2017. Fitness and movement of Xanthomonas perforans and the effect of AvrBst on pathogenesis in tomato transplant production. 2017 Meeting of the Southern Division of the American Phytopathological Society, College Station, TX.
  • Type: Journal Articles Status: Accepted Year Published: 2021 Citation: Klein-Gordon, J., Timilsina, S., Xing, Y., Abrahamian, P., Garrett, K, Jones, J.B., Vallad, G.E., and Goss, E.M. 2021. Whole genome sequences reveal the Xanthomonas perforans population is shaped by the tomato production system. ISME Journal (accepted).
  • Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Liao, Ying-Yu. 2020. Antibacterial potential of nano magnesium, and role of type vi secretion system of Xanthomonas perforans. Doctoral dissertation, University of Florida. https://etd.uflib.ufl.edu.
  • Type: Book Chapters Status: Published Year Published: 2017 Citation: Miller, S. A., Jones, J. B. and Kurowski, C. 2017. Detection of Xanthomonas spp. in tomato and pepper seeds Fatmi, M., Walcott, R. and Schaad, N. (eds). Chapter 19 IN: Detection of Plant-Pathogenic Bacteria in Seed and Other Planting Material, Second Edition. St. Paul, MN: APS Press. 372 pp.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Abrahamian, P., S. Timilsina, G.V. Minsavage, J.B. Jones, E.M. Goss, and G.E. Vallad. 2018. Characterizing the epidemiological link between transplant and field outbreaks of bacterial spot on tomato with whole genome sequencing. International Congress of Plant Pathology (ICPP) 2018, Boston, MA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Abrahamian, P, GE Vallad, S Timilsina, E Goss, and J Jones. 2017. From seed to fork: Advancing integrated practices for managing tomato bacterial spot. Proceedings from the 2017 Florida Tomato Institute, Naples, FL.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Abrahamian, P., S. Timilsina, G.V. Minsavage, N. Potnis, E. Goss, J.B. Jones, and G.E. Vallad. 2017. The type III effector AvrBst enhances Xanthomonas perforans fitness in tomato. 2017 Annual Meeting of the American Phytopathological Society, San Antonio, TX
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Abrahamian, P., S. Timilsina, G.V. Minsavage, E.M. Goss, J.B. Jones, and G.E. Vallad. 2017. Xanthomonas perforans population dynamics and genetics from seedling to field-grown tomato. 32nd Annual Tomato Disease Workshop, Wimauma, FL.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Adkison, H. A., Wen, and G.E. Vallad. 2017. Effect of At-Plant Drench Applications of Actigard on Tomato Seedlings for Bacterial Leaf Spot Control. 2017 Annual Meeting of the American Phytopathological Society, San Antonio, TX.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Anderson, Taylor. 2018. Pyramiding resistances to bacterial spot and bacterial speck in elite fresh market tomato. 47th Tomato Breeders Roundtable. April 4-6th, 2018. Wooster, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bernal, E, Deblais, L, Rajashekara, G, Rotondo, F, Miller, SA, Francis, DM. 2019. Application of in vivo imaging system (IVIS) and labeled Xanthomonas strains to quantify bacterial colonization as a measure of disease resistance. Phytopathology 109 (10), 87-88
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bernal, E, Deblais, L, Rajashekara, G, Rotondo, F, Miller, S, Francis, DM. 2019. In vivo imaging of labeled Xanthomonas strains permits quantification of pathogen growth and assessment of disease resistance in tomato. Tomato Breeders Roundtable and Tomato Disease Workshop, Clearwater Beach Florida, November 17 21, 2019
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bernal, E., L. Deblais, G. Rajashekara, F. Rotondo, S.A. Miller, and & D.M. Francis. 2019. Application of in vivo imaging system (IVIS) and labeled Xanthomonas strains to quantify bacterial colonization as a measure of disease resistance. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Bernal, Eduardo, Debora Liabeuf and David Francis, 2018. Background Genome Selection for Rapid Introgression and Evaluation of Quantitative Trait Loci (QTL) for Resistance in Tomato to Multiple Xanthomonas spp. National Association of Plant Breeders Conference August 7th-10th 2018, Guelph, Ontario.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Bernal, Eduardo, Debora Liabeuf and David Francis, 2018. Evaluating Quantitative Trait Loci (QTL) Sources of Resistance in Tomato to Multiple Xanthomonas Spp. Ohio State University Plant Sciences Symposium, April 7th 2018, Wooster, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Bernal, Eduardo, Debora Liabeuf and David Francis, 2018. Background Genome Selection for Rapid Introgression and Evaluation of Quantitative Trait Loci (QTL) for Resistance in Tomato to Multiple Xanthomonas spp. 47th Tomato Breeders Roundtable, April 4th-6th 2018, Wooster, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Bernal, Eduardo, Loic Deblais, Gireesh Rajashekara, Francesca Rotondo, Sally Miller, David Francis, 2018 Monitoring bacterial colonization of labeled Xanthomonas strains on tomato genetic resources nearly isogenic for resistance loci. 12th Annual The Ohio State University Horticulture and Crop Science Research Symposium, October 11th-12th 2018, Wooster, OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Bhandari, R, GV Minsavage, E Newberry, J Klein, EM Goss, GE Vallad, JB Jones, and N Potnis. 2018. Dynamics of chromosomal and plasmid-borne copper resistance systems in Xanthomonas perforans populations. International Congress of Plant Pathology (ICPP) 2018: Plant Health in A Global Economy, Boston, MA, USA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bigott, A, JD Barak, R Lankau, GE Vallad, S Hutton. 2019. Bacterial community response to bacterial spot disease and resistance in tomatoes. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Francis, David. 2020. So Many Genomes, So Little Time: The Future of Plant Breeding. Department of Horticultural Sciences, Texas A & M University. Available at: https://hortsciences.tamu.edu/horticulture-seminar-video-archive/
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Chitwood-Brown, J., G.E. Vallad, T.G. Lee, S. Hutton. 2020. Improving resistance to Fusarium wilt race 3 of tomato by addressing negative associations at the I-3 locus. HortScience 55(9):S157. (Abstr.)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Chitwood-Brown, J., S. Hutton, G.E. Vallad, and T.G. Lee. 2019. Eliminating Linkage-drag to improve resistance to Fusarium wilt race. Tomato Breeders Roundtable and Tomato Disease Workshop, Clearwater Beach, FL USA. (Abstr.)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Chitwood, J., and S.F. Hutton. 2018. Discovery and improvement of novel sources of resistance to Fusarium wilt race three of tomato. 47th Tomato Breeders Roundtable, Wooster, OH. p. 23 (Abstr.)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Francis, David, Miller, S, Rotondo, F, Bernal, E. 2020 Bacterial spot of tomato as a case study for advancing plant health through knowledge of global pathogen diversity and resistance deployment. The Ohio State University Plant Science Symposium (Corteva Plant Sciences Symposia Series). Available at: https://u.osu.edu/plantsciencessymposium/program/
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Francis, D. 2019. Discovery, introgression, and pyramiding of disease resistance in tomato. Tomato Breeders Roundtable and Tomato Disease Workshop, Clearwater Beach Florida, November 17 21, 2019
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Francis, DM, Bernal, E, Orchard, C, Subode, S. 2019. New approaches in the discovery and introgression of disease resistance genes from wild tomato. IV ISHS Tomato Disease Symposium, National Chung Hsing University, Chinese Taipei (Taiwan), May 6-9, 2019
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Francis, David. 2018. Experience with Genomic Selection in Processing Tomato. 47th Tomato Breeders Roundtable. April 4-6th, 2018. Wooster, OH.
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Francis, David. 2018. Genomic Selection in Tomato Breeding. 8th Breeding with Genomics Course, February 13-15, 2018, Davis, CA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Francis, David. 2018. Genomic Selection in Tomato Breeding. Genome Assisted Plant Breeding Workshop. Oct. 6-7, Chiang Mai, Thailand
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Francis, David. 2018. Genomic Selection in Tomato Breeding. October 25, UNIVERSIDAD NACIONAL DE CUYO - FACULTAD DE CIENCIAS AGRARIAS, Mendoza, Argentina.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Francis, D. , Eduardo Bernal, Debora Liabeuf, Darlene De Jong, Taylor Anderson, Stella Zitter, Martha Mutschler-Chu. 2017. Prebreeding to Combine Resistances to Pathogens From Three Kingdoms in Processing and Fresh-Market Tomato. National Association of Plant Breeders, August 7-10, 2017, Davis, CA. TU67. https://napb2017.ucdavis.edu/program-2/
  • Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Hutton, Samuel. 2020. Current Breeding Strategies to Address Decades-old Disease Challenges in Florida Fresh Market Tomato, Texas A & M University
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Hutton, S.F., T.G. Lee and G.E. Vallad. 2018. Tomato variety improvement. In: Tomato Research Report 2017-2018. University of Florida, IFAS Research, p. 15-21.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Hutton, S.F., B. Staskawicz, A. Schultink, G.E. Vallad, J.B. Jones, and D. Horvath. 2018. Field control of bacterial spot through introduction of novel resistance alleles in tomato. Proceedings from the 2018 Florida Tomato Institute, Naples, FL.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Iruegas-Bocardo, F., Timilsina, S., Jibrin, M., Minsavage Jr., G. V., Abrahamian, P., Egel, D. S., Creswell, T., Miller, S. A., Rotondo, F., Louws, F. J., Adhikari, T., Trueman, C., Roach, R., Coutinho, T., Pruvost, O. P., Nguyen, N. T. T., Luo, L., Kebede, M., Potnis, N., Vallad, G. E., Jones, J. B. and Goss, E. M. 2019. Effector profiles of Xanthomonas perforans and X. euvesicatoria provide insights into the evolution of host range and virulence in BLS pathogens. Phytopathology 109:S2.21-22.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Iruegas-Bocardo, F, S Timilsina, MO Jibrin, GV Minsavage, P Abrahamian, DS Egel, T Creswell, S Miller, F Rotondo, FJ Louws, T Adhikari, C Trueman, R Roach, T Coutinho, O Pruvost, NTT Nguyen, L Luo, M Kebede, N Potnis, GE Vallad, JB Jones, and EM Goss. 2019. IS-MPMI XVIII Congress, Glasgow, Scotland.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Iruegas-Bocardo, F., Timilsina, S., Jibrin, M., Minsavage Jr., G. V., Abrahamian, P., Egel, D. S., Creswell, T., Miller, S. A., Rotondo, F., Louws, F. J., Adhikari, T., Trueman, C., Roach, R., Coutinho, T., Pruvost, O. P., Nguyen, N. T. T., Luo, L., Kebede, M., Potnis, N., Vallad, G. E., Jones, J. B. and Goss, E. M. 2019. Effector profile analysis of the tomato and pepper pathogens Xanthomonas perforans and X. euvesicatoria. Molec. Plant-Microbe Int. 32:S1.186.


Progress 09/01/19 to 08/31/20

Outputs
Target Audience:Target audience during this reporting period include commercial vegetable growers, transplant operations, vegetable producers, seed company representatives, county extension agents, and researchers in plant pathology, plant-microbe interactions, and plant breeding. Changes/Problems:Covid-19 related closure and restrictions delayed several field trials and the completion of various trials; an extension was requested to finalize research. What opportunities for training and professional development has the project provided? A visiting scientist, Associate Professor Dr. D. Yang from the Institute of Plant Protection, Chinese Academy of Agriculture Science, Beijing enhanced his analytical skills working on the project with Dr. Alan Taylor. A visiting scientist, Assistant Professor Dr. X. Yan from the Institute of Plant Protection, Chinese Academy of Agriculture Science enhanced her professional skills working on the project with Dr. Hilary Mayton. Rotondo F., Amrhein, J., Vargas, A., Miller S.A. Plant Health 2020, APS Annual Meeting (virtual). Rotondo F. Saint-Preux C., Miller S.A., Lewis Ivey M.L. 35th Tomato Disease Workshop, Univ. California ANR, 2020 (virtual). Rotondo F., Bernal E., Miller S.A. Plant Health 2019, APS annual Meeting, Cleveland, OH, USA. Rotondo F., Miller S.A. 34th Tomato Disease Workshop, 2019, Clearwater, FL, USA. Rotondo F., Miller S.A. 33rd Tomato Disease Workshop, 2018, Chincoteague, VA, USA. Rotondo F., Moodispaw M., Sally Miller 32nd Tomato Disease Workshop, 2017, Tampa, FL, USA. Klein-Gordon, J., F. Bocardo, A. Sharma, P. Abrahamian & S. Timilsina presented atEmerging Pathogens Institute, Research Day, Gainesville, FL; Plant Health 2019 and Plant Health 2020; Tomato Disesae Workshop 2019. How have the results been disseminated to communities of interest? Klein-Gordon, J., P. Abrahamian, S. Timilsina, G.V. Minsavage, J.B. Jones, G.E. Vallad, E.M. Goss. 2019. Recent state-wide survey reveals continued shifts in Xanthomonas populations in Florida commercial tomato fields. University of Florida, Emerging Pathogens Institute, Research Day, Gainesville, FL. *Rotondo F., Miller S.A. Biopesticides to control spot, canker in greenhouse transplants, MID-ATLANTIC Fruit & Vegetable Convention, January 28, 2020, Hershey, PA, USA. *Miller, S. A. Managing bacterial diseases of vegetables. Salem Produce Growers Meeting, February 25, 2020, Columbiana, OH. *Miller, S. A. Integrated approaches to managing bacterial diseases of tomatoes. Ontario Fruit and Vegetable Conference, Niagara Falls, Ontario, Canada, February 20, 2019. *Miller, S. A. and Rotondo, F. Managing bacterial spot in tomatoes. Mid-Atlantic Fruit and Vegetable Convention, Hershey, PA, January 29-30, 2019. *Miller, S. A. Managing bacterial diseases of vegetables. Mid-Ohio Growers Meeting, Mt. Hope, OH, January 12, 2018. *Francis, David. 2020. Pathogen Populations as a Moving Target. 2020 Indiana Horticultural Congress Feb. 11-13, 2020, Indianapolis, IN. *Vallad, G.E. 2019. Integrated approaches to bacterial spot management for tomatoes - A Florida perspective. VII Simposio Nacional y VI Internacional de Bacterias Fitopatógenas y III Simposio de bacterias benéficas de las plantas, Guadalajara, Jalisco, Mexico. (oral presentation) *Vallad, G.E. 2019. Movement and management of tomato bacterial spot during seedling production. Ontario Tomato Seedling Growers Meeting, University of Guelph, Ridgetown, Ontario, Canada. (oral presentation) Vallad, G.E. 2019. Common tomato diseases of Florida. Lake County Master Gardener's Training Meeting. Tavares, FL. (oral presentation) Blogs Miller, S. A. Ohio Veggie Disease News. Bacterial disease management in vegetable crops without copper? July 18, 2020. http://u.osu.edu/miller.769/. INTERNATIONAL EFFORTS: 2019Visited small fruit and vegetable production areas in Jalisco, Mexico to develop collaborative efforts with researchers from the University of Guadalajara, Mexico, 3days What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Per Objective 1: Activity: In the Southeast, examined genetic variation of 585 Xp strains from 70 tomato fields in Florida and Georgia as related to production chain variables, and genomic variation of 300+ of these strains; examined role of transplant production in outbreaks of Xp in production fields; and evaluated role of the horizontally acquired effector XopJ2 to Xp fitness. Results: Identified six genetic groups of Xp in Florida based on nucleotide variation in core genes. Found copper tolerance dominates all Xp strains in Florida, with streptomycin resistance predominantly associated with a single genetic group of strains. In transplant studies, found incubation periods of 5-7 days and aerosolization from overhead watering systems allows Xp to spread rapidly in transplant operations (2 to >30 cm/day) depending on conditions, due to bacterial movement through aerosols generated from overhead irrigation systems. Determined that removal of >1 to 3 meters of asymptomatic seedlings surrounding symptomatic plants necessary to limit pathogen spread. Based on whole genome SNP analysis, 60 and 100% Xp strains recovered during outbreaks at two separate field operations could be traced back to strains initially isolated from the seedlings previously sampled at transplant production facilities. While XopJ2 had no effect on in planta growth and limited Xp host-range, strains with XopJ2 exhibited an ability to spread faster and further distances over XopJ2 mutants under field conditions. Significant outcomes and impacts: Genome-based epidemiological studies evaluating isolates collected from 70 production fields to production history (transplant production and seed source), found evidence that farm operations that outsourced transplant production were often associated with more diverse Xp populations than those farm operations that produced their own transplants, although other production factors also influenced population structure. Per Objective 2: Activity: Evaluated survival of 5 Xg and five Xp strains on artificially infested tomato seeds; and pathogen transmission to subsequent seedlings. Evaluated transmission from seed to seedling in laboratory assays for tomato seed naturally and artificially infested with Xe. Results: Xg and Xp populations declined over time on artificially infested tomato seeds. Xp persisted on seeds slightly longer than Xg. A high degree of strain-to-strain variability in survival on tomato seeds within both species was observed. The number of infested seeds influenced the number of diseased seedlings. A higher number of infested seeds tended to result in a higher level of foliar disease severity and disease incidence. PCR using the hrpB7 primers confirmed presence of the Xv on naturally infested seeds and germinating seedlings. However, seed to seedling transmission was negligible. Activity: Evaluated nanoparticle materials of silver (AgNP), magnesium oxide (MgONP), for BST management when applied as seedtreatments. Results: When AgNP and MgONP were evaluated as seed treatments against mixtures of Xp or Xg strains on artificially infested seed, two evaluated rates effectively reduced Xanthomonas levels and incidence on seed, and the incidence and severity of BST on corresponding tomato seedlings. Significant outcomes and impacts: Successfully identified several nanoparticle materials that exhibit efficacy against Xp and Xg in seed, seedling, and field applications. Per objective 3: Activity: Conducted CRISPR-Cas9 editing to modify the tomato ortholog of the recessive pepper CaBs5 gene (SlBs5 gene) to confer BST resistance, as well as a CaBs5-like paralog (SlBs5-like) that shares a promoter region in pepper but has not been associated with BST resistance. Results: Generated targeted mutations for SlBs5 and/or SlBs5-like in the second or third exon. Successful transformants were self-pollinated and the subsequent progeny were genotyped to indicate favorable mutations in the endogenous tomato Bs5 genes. Performed Xanthomonas inoculation assays on SlBs5/SlBs5-like Cas9-edited tomatoes, demonstrating six mutant lines exhibited a 10-fold decrease of bacterial growth in internal populations of X. euvesicatoria strain 85-10 or X. perforans strain 4B compared to susceptible wild-type in tomatoes leaves. Field evaluations of a SlBs5/SlBs5-like Cas9-edited tomato line exhibited reduced susceptibility to Xp (Race 4) in trials conducted in Florida. Significant outcomes and impacts:Developed SlBs5/SlBs5-like Cas9-edited tomato lines exhibited reduced susceptibility to Xp (Race 4) in trials conducted in Florida, demonstrating the effective use of CRISPR-Cas9 to modify orthologous genes in tomato that play a role in BST resistance in other solanaceous hosts. Per objective 4: Activity: Conducted large-plot trials to evaluate BST impact on tomato yields caused by Xp and Xg in Ohio and Florida, respectively, and cost effectiveness of field treatments. Results: High levels of BST severity, induced by repeated inoculations of plots, statistically reduced marketable yields by 30% on average, compared to non-inoculated plots across three separate trials; while plots inoculated once reduced marketable yields by 16% on average. Regardless of efficacy, BST treatments had little statistical impact on marketable yields, demonstrating importance of deploying host resistance for management. Significant outcomes and impacts:Regardless of efficacy against BST, chemical control had little impact on marketable yields, demonstrating importance of limiting inoculum and deploying host resistance for management.

Publications


    Progress 09/01/18 to 08/31/19

    Outputs
    Target Audience:Target audience during this reporting period include commercial vegetable growers, transplant operations, vegetable producers, seed company representatives, county extension agents, and researchers in plant pathology, plant-microbe interactions, and plant breeding. Changes/Problems:A one year, no-cost extension will be requested to finish research objectives and the preparation of publications. What opportunities for training and professional development has the project provided?Participating graduate students and post-doctoral scholars are working on Xanthomonas strain characterization, as well as tomato breeding aspects of the project. Post-docs and graduate students attended and made presentations during the Tomato Disease Workshop, the Tomato Breeder's Roundtable, Divisional and Annual meetings of the American Phytopathological Society, as well as the American Society of Horticultural Sciences. Participating graduate students at UF updated extension pulications on the BST management. How have the results been disseminated to communities of interest?Participating PIs, graduate students and post-docs have presented updates on work to various professional organizations and to the tomato industry. These presentations were listed previously under products. At the joint 2019Tomato Disease Workshop and Tomato Breeders Roundtable, growers and industry stakeholders were invited to participate in the a special meeting of the SCRI research team; participating graduate students and post-docs helped to coordinate and moderate the meeting in Clearwater, Florida. What do you plan to do during the next reporting period to accomplish the goals?Per objective 1: Continue and finish phylogenetic assessment of BST causing xanthomonas populations, evaluating diversity within eastern US and how Xg and Xp populations relate to global populations; as well as characterize and evalute effector divergence in US and global Xp populations. Per objective 2: For SM work:Improve the antimicrobial efficacy of the SMs against Xanthomonas on infected tomato seedlings and infested tomato seeds using additives/surfactants to i) Improve the adhesion and dispersion of the SMs on the plant tissues, and 2) protect the SMs against the environmental fluctuations (UV, temperature, humidity). Combine the SMs with other control methods (biocontrol agents, novel small peptides,...) to enhance the control of Xanthomonas in tomato production. Repeat seed assays to demonstratethe efficacy of nano-silver and nano magnesium oxide particles, try to include SMs as well. Per objective 3:Continue breeding efforts with MAS and pyramiding transgenes into specific breeding lines; as well as continue development of tomato lines with Cas9 edited susceptibility alleles. Per objective 4: Finish the collection of economic data related to tomato production; evaluate efficacy, cost effectiveness and risk efficiency of different BST management practices for both fresh and processed tomatoes in Ohio. Finish field trials to assess impact of BST on yield to develop a disease threshhold model and assess cost effectiveness of deployed BST treatments.

    Impacts
    What was accomplished under these goals? Per objective 1: At two Florida grower operations, Xp strains isolated from transplants prior to roguing were compared to strains collected from final field locations prior to harvest; SNP and core genome MLST (cgMLST)showed that 60 and 100% of isolates in the field were likely from the transplant facility. cgMST comparisons of global Xp strains demonstrated geographic distribution of strains:group 2 strains are the most common in US (including one strain from Mexico); group 1 strains are quite diverse and found throughout the world; group 3 strains in US,China and Australia; suggestions of other distinct phylogenetic groups. Bayesian analyses, based on core SNPs, were used to assess temporal diversification of BST causing xanthomonas populations. Xg strains likely diverged into two groups in early 1970s; whereas Xp strains underwent an initial divergence in 1980s and then several major diversification events throughout early 2000s. Per objective 2: For small molecule (SM) research: evaluated 17 SMs against 119 Xanthomonas isolates responsible for BST; which showed varying antimicrobial specificity and efficacy among strains. SEM showed that the eight previously selected SMs deformed Xanthomonas gardneri cells upon exposure.The same 8 SMs also showed some bactericidal and bacteriostatic activity against other diverse Xanthomonads and other phyobacteria.Using a MBEC (minimal biofilm eradication concentration) assay, it was demonstrated that the 8 SMs effectively killed Xg, Xp, Xe, and Xv protected in the biofilm; however, in some cases the concentration needed to kill Xanthomonas was 4 times higher compared to the normal MBC previously determined. All 8 SMs reduced growth of Xg,Xp,Xe, and Xv on tomato plants; and also exhibited some antibacterial activity against xanthomonads on artificially infested tomato seeds. Nanosilver and nanomagnesium oxide materials were evaluated as seed treatments to assess their effect on seed germination; products had minimalimpact on seed germination (performed equivalent orbetter than hot water seed treatments) and nanosilver appeared to have stimulate seed germination and initial growth. Bioassays showed that nanosilver seed treatments were effective at decreasing the level of Xg and Xp seed infestation and disease incidence in seedling growouts. Per objective 3:Continue breeding efforts with MAS and pyramiding transgenes into specific breeding lines; as well as continue development of tomato lines with Cas9 edited susceptibility alleles. Per objective 4: Initial field trials in Ohio and Florida were conducted to measure the impact of BST on tomato yields. Economic assessment of BST impact and cost-effectiveness of treatments are in progress.

    Publications

    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Saint-Preux, C, SA Miller, ML Ivey 2019. Assessment of the Relationship Between Bacteria Leaf Spot Severity and Crop Yield of Fresh Market and Processing Tomato. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bernal, E., L. Deblais, G. Rajashekara, F. Rotondo, S.A. Miller, and & D.M. Francis. 2019. Application of in vivo imaging system (IVIS) and labeled Xanthomonas strains to quantify bacterial colonization as a measure of disease resistance. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Srivastava, V, L Deblais, D Kathayat, Y Helmy, SA Miller, G Rajashekara. 2019. Discovery of small molecule growth inhibitors to control bacterial leaf spot (BLS) disease of tomato. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rotondo, F, E Bernal, DM Francis, SA Miller. 2019. Distribution and Characteristics of Xanthomonas Species Causing Bacterial Spot in Midwestern Processing Tomatoes. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Iruegas-Bocardo, F, S Timilsina, M Jibrin, GV Minsavage, P Abrahamian, DS Egel, T Creswell, SA Miller, F Rotondo, FJ Louws, T Adhikari, C Trueman, R Roach, T Coutinho, OP Pruvost, NTT Nguyen, L Luo, M Kebede, N Potnis, GE Vallad, JB Jones, EM Goss. 2019. Effector profiles of Xanthomonas perforans and X. euvesicatoria provide insights into the evolution of host range and virulence in BLS pathogens. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Iruegas-Bocardo, F, S Timilsina, MO Jibrin, GV Minsavage, P Abrahamian, DS Egel, T Creswell, S Miller, F Rotondo, FJ Louws, T Adhikari, C Trueman, R Roach, T Coutinho, O Pruvost, NTT Nguyen, L Luo, M Kebede, N Potnis, GE Vallad, JB Jones, and EM Goss. 2019. IS-MPMI XVIII Congress, Glasgow, Scotland.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Liao, Y-Y, AL Strayer-Scherer, Z Huang, S Santra, JC White, A Mukherjee, R De La Torre-Roche, Q Fan, S Wright, L Ritchie, J Colee, GE Vallad, JH Freeman, JB Jones, ML Paret. 2019. A novel alternative to copper bactericide: Magnesium nano-materials for management of bacterial spot disease of tomato. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Jibrin, M, N Potnis, S Timilsina, GV Minsavage, VM Shutt, TA Coutinho, OP Pruvost, MI Siri, MJ Pianzzola, AM Quezado Duval, EV Nikolaeva, DS Egel, T Creswell, GE Ruhl, L Maynard, P Gulig, GE Vallad, PD Roberts, EM Goss, JB Jones. 2019. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bigott, A, JD Barak, R Lankau, GE Vallad, S Hutton. 2019. Bacterial community response to bacterial spot disease and resistance in tomatoes. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Klein, J, P Abrahamian, Y Xing, J Fulton, GV Minsavage, S Timilsina, ML Paret, KA Garrett, JB Jones, EM Goss, and GE Vallad. 2019. Its complicated: The Xanthomonas perforans population across Florida commercial tomato fields. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Liao, Y-Y, AL Strayer-Scherer, Z Huang, S Santra, JC White, R De La Torre-Roche, Q Fan, S Da Silva, GE Vallad, JH Freeman, JB Jones, and ML Paret. 2019. The efficacy of MgO bactericide against bacterial spot disease of tomato is particle size-dependent. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Timilsina, S, GP Cavalcante, R Ram�rez, MDS Bezerra de Araujo, J Tian, GV Minsavage, EM Goss, GE Vallad, JB Jones, and N Potnis. 2019. The effect of XopQ and XopJ4 on host specificity varies with the Xanthomonas perforans genetic background. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Sharma, A, S Timilsina, P Abrahamian, PS Ojiambo, J Colee, GV Minsavage, GE Vallad, EM Goss, and JB Jones. 2019. Role of avrBsT in dispersal of Xanthomonas perforans and severity of bacterial spot of tomato. Annual Meeting of the American Phytopathological Society, Plant Health 2019, Cleveland, OH.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Liao, Y.Y., A. Strayer-Scherer, J.C. White, R. De La Torre-Roche, L. Ritchie, J. Colee, G.E. Vallad, J. Freeman, J.B. Jones, and M.L. Paret. 2019. Particle-size dependent bactericidal activity of magnesium oxide against Xanthomonas perforans and bacterial spot of tomato. Sci Rep 9, 18530.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Abrahamian, P., J.B. Jones, G.E. Vallad. 2019. Efficacy of copper and copper alternatives for management of bacterial spot on tomato under transplant and field production. Crop Protection 126:104919.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Timilsina, S., J.A. Pereira-Martin, G.V. Minsavage, F. Iruegas-Bocardo, P. Abrahamian, N. Potnis, B. Kolaczkowski, G.E. Vallad, E.M. Goss, and J.B. Jones. Multiple Recombination Events Drive the Current Genetic Structure of Xanthomonas perforans in Florida. Frontiers in Microbiology 10:448. doi: 10.3389/fmicb.2019.00448.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Abrahamian, P., S. Timilsina, G.V. Minsavage, N. Potnis, J.B. Jones, E.M. Goss, and G.E. Vallad. 2019. Molecular epidemiology of Xanthomonas perforans outbreaks in tomato plants from transplant to field as determined by singlenucleotide polymorphism analysis. Appl Environ Microbiol 85:e01220-19. https://doi.org/10.1128/AEM.01220-19.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Timilsina, S., S. Kara, M.A. Jacques, N. Potnis, G.V. Minsavage, G.E. Vallad, J.B. Jones, M. Fischer-Le Saux. 2019. Reclassification of Xanthomonas gardneri (ex `uti? 1957) Jones et al. 2006 as a later heterotypic synonym of Xanthomonas cynarae Tr�baol et al. 2000 and description of X. cynarae pv. cynarae and X. cynarae pv. gardneri based on whole genome analyses. Int J Syst Evol Microbiol 69:343349. DOI 10.1099/ijsem.0.003104.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Liao, Y.-Y., A.L. Strayer-Scherer, J. White, A. Mukherjee, R. De La Torree-Roche, L. Ritchie, J. Colee, G.E. Vallad, J.H. Freeman, J.B. Jones, and M.L. Paret. 2019. Nano-Magnesium Oxide: A Novel Bactericide Against Copper-Tolerant Xanthomonas perforans Causing Tomato Bacterial Spot. Phytopathology 1:52-62.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Abrahamian, P., J.M. Klein, J.B. Jones, G.E. Vallad, and R.A. Melanson. 2019. First Report of Bacterial Spot of Tomato Caused by Xanthomonas perforans in Mississippi. Plant Disease 103:147-147.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Strayer-Scherer, A., Liao, Y.-Y., Abrahamian, P., Timilsina, S., Paret, M., Momol, T., Jones, J., & Vallad, G. (2019). [PP353] Integrated Management of Bacterial Spot on Tomato in Florida. EDIS, 2019(6), https://journals.flvc.org/edis/article/view/108765
    • Type: Other Status: Published Year Published: 2019 Citation: Vallad, G.E. 2019. Getting the jump on tomato bacterial spot begins with transplant health! Vegetable and Specialty Crop News. June 2019.


    Progress 09/01/17 to 08/31/18

    Outputs
    Target Audience:Target audience during this reporting period include commercial vegetable growers, transplant operations, vegetable producers, seed company representatives, county extension agents, and researchers in plant pathology, plant-microbe interactions, and plant breeding. Changes/Problems:We have run into difficulties in obtaining seed naturally infested with Xanthomonas; efforts to obtain sufficient seed from seed companies or through published artificial flower inoculation methods have been unsuccessful. We plan to harvest seed from BLS trials in Ohio, Florida and New York to generate infested seed. If this proves insufficient, we will resort to vacuum infiltration methods. What opportunities for training and professional development has the project provided?At the University of Florida, participating graduate students and post-doctoral scholars are working on Xanthomonas strain characterization, as well as tomato breeding aspects of the project. Post-docs and graduate students attended and made presentations during the Tomato Disease Workshop,the Tomato Breeder's Roundtable, Divisional and Annual meetings of the American Phytopathological Society, as well as the American Society of Horticultural Sciences. In Dr. Rajashekara's program,Vishal Srivastava learnt techniques about high-throughput screening, toxicity assays, and designing plant experiments. Loic Deblais learnt to manage large set of data using publically available chemistry database (Pubchem and ChemMine). Loic also assisted Vishal Srivastava through out the experiments of this project and thought plant pathology techniques. Further, both scientists communicated the results generated during The Ohio State University meetings and interacted with several scientific disciplines (Plant pathology, Horticulture and crop sciences, and Veterinary preventive medicine). How have the results been disseminated to communities of interest?Participating PIs, graduate students and post-docs have presented updates on work to various professional organizations and to the tomato industry. These presentations were listed previously under products. At the 2017 and 2018 Tomato Disease Workshops, growers and industry stakeholders were invited to participate in the a special meeting of the SCRI research team. What do you plan to do during the next reporting period to accomplish the goals?Per objective 1: Continue collection surveys and characterization of Xanthomonas strains from eastern US and from global collections. Conduct genome sequencing of representative strains. Conduct SNP and effector analyses to examine genetic relationship between strains from seed production areas and US fields.Continue testing strains for bactericide resistance to determine current status of populations. Per objective 2: Continue efforts to evaluate and nanomaterials in field trials and identified small molecules against diverse Xanthomonas strains. Donfirm the antimicrobial efficacy of the small molecules on infected tomato seedlings, and we will test the toxicity and clearance ability of the small molecules on tomato seeds. Upon completion of these studies, a manuscript will be submitted to the journal of phytopathology by fall 2018. Continue efforts to develop infested seed or harvest seed from BLS field trialsto evaluate bactericidal seed treatments. Per objective 3: Continue breeding efforts with MAS and pyramiding transgenes into specific breeding lines; as well as continue development of tomato lines with Cas9 edited susceptibility alleles. Per objective 4: Develop and continue collection of economic data related to tomato production; evaluate efficacy, cost effectiveness and risk efficiency of different BST management practices for both fresh and processed tomatoes in Ohio;continue to visit other tomato nurseries in Florida and compile transplant production budget; andmodel and analyze the dynamics of bacterial spread of strains over time and space.

    Impacts
    What was accomplished under these goals? Per objective 1: Continued collection, characterization, sequencing of Xanthomonas strains from US and abroad; collections through 2017-2018 indicate diversifying population in Florida. Continue characterization of effectors and core genome analysis of sequenced strains.From a 2017 survey of 16 Ohio or Indiana processing tomato fields, 64 Xanthomonas strains were isolated from tomato fruits with bacterial leaf spot (BLS) symptoms. Species were identified using Box-PCR fingerprinting. Of the 64 strains, 28 (44%) were X. gardneri, 17 (26.5%) were X. perforans, two (3%) were X. euvesicatoria and 17 (26.5%) exhibited a mixed fingerprint reflecting both X. gardneri and X. perforans profiles. These mixed profile strains are morphologically similar to X. perforans. Forty-five of these strains were selected based on species and origin and shipped to the University of Florida for further analysis, including whole genome sequencing. Per objective 2: Continued field evaluation ofadvanced nanoformulated copper composites in greenhouse and field trials.Tomato fruit infection by Xanthomonas gardneri was evaluated using bioluminescent strain SM775-12bio. Visual lesions and bioluminescent X. gardneri were observed 6 days post inoculation (DPI) of tomato fruits <2 cm in diameter. Internal colonization of tomato fruits was observed within 42 DPI, including colonization of the seed cavity. Out of the 591 small molecules that inhibited both X. gardneri and X. perforans, 17 small molecules had no antimicrobial activity towards several other plant, animal, and human pathogens (n=7) at 100μM. These 17 small molecules were cidal against other X. gardneri (n=50), X. perforans (n=50), X. vescicatoria (n=1), and X. euvescicatoria (n=30) at 200μM and displayed a minimal bactericidal concentration ranging between 50μM and 200μM across the four Xanthomonas species. Further, the 17 small molecules were effective against other Xanthomonas species (n=8) isolated from fruits, leafy greens, and vegetables but did not affect the growth of other plant pathogenic (n=14) and beneficial (n=12) bacteria. Eight Xanthomonas specific small molecules (XSM1, 2, 5, 8, 9, 11, 12, and 16) with the best antimicrobial activity were selected to test their toxicity and ability to clear Xanthomonas in tomato tissues. The eight XSMs did not result in any symptoms on tomato foliage and fruits at 14 days post-treatment when treated with 500 μM.The XSMs were effective in control Xanthomonas when seedlings were treated (500 μM of SM) on the foliage two days post inoculation. All small molecules reduced at least by 2.0-log Xanthomonas population in infected seedlings compared to the water treated controls at 7 days post-inoculation. Further, XSM1 displayed antimicrobial efficacy similar to streptomycin and copper sulfate (500 μM), which reduced Xanthomonas population by 3.05-log compared to the water treated seedlings at 7 days post-inoculation. The reduction in Xanthomonas population in seedling was also associated with a reduction in the severity of the symptoms on the foliage at 7 days post-inoculation. XSM1, 2, 5, and 12 reduced up to 15.4% of symptoms on the foliage compared to the water treated seedlings, which showed symptoms on ~16.9% of the foliage at 7 days post-inoculation. These results suggest that XSM 1, 2, 5, and 12 represent a good alternative to the intensive use of broad-spectrum copper-based management methods. Per objective 3: A recessive allele of the Bs5 gene, bs5, from pepper was found to confer disease resistance against Xanthomonas euvesicatoria, the causative agent of bacterial spot of pepper and tomato. Bacterial spot disease is globally spread and has caused major productivity losses in commercial crops. Deployment of the bs5 allele in tomato cultivars has the potential to confer disease resistance against bacterial spot. Pepper and tomato are not sexually compatible, thus classical plant breeding strategies cannot be employed to establish bs5 resistance. The causative mutation of Cabs5 is a six nucleotide deletion in the third and last exon. This results in a double leucine deletion at the C-terminus of the encoded protein. CaBs5 is closely neighbored by a CaBs5-like paralog, likely the result of gene duplication. As of yet, the Cabs5 allele has only been found in the CaBs5 gene in pepper, suggesting no suppressive effects on Cabs5 resistance by the CaBs5-like gene. The orthologs of pepper CaBs5 and CaBs5-like have been found in tomato (Solanum lycopersicum). The orientation of the SlBs5 gene in the chromosome relative to SlBs5-like is identical to that of CaBs5/CaBs5-like genes. It remains to be seen whether the SlBs5-like gene will have any suppressive effects if the six nucleotide deletion of the bs5 allele were to be introduced in tomato. Our aim is to test bs5 resistance in tomato using transgenics, then introduce the bs5 allele into tomato through Cas9-mediated homology-directed repair. Stable transformations of the tomato variety FL8000 were done with either the resistant pepper (Cabs5) or susceptible pepper (CaBS5) alleles along with Cas9 targeting tomato SlBs5 and SlBs5-like genes. Gene knockout of SlBs5 and SlBs5-like was done to assure no suppressive effect on the Cabs5/BS5 gene. Preliminary bacterial inoculation assays on Cabs5 transformed plants showed a 10-fold decrease of bacterial growth of Xanthomonas euvesicatoria strain 85-10 compared to susceptible wild-type tomatoes (Figure 1). T0 Cabs5 or CaBS5 tomatoes were self-fertilized and seeds were used to propagate T1 populations. T1 plants were genotyped to confirm mutations of SlBs5 and SlBS5-like genes and also to confirm successful integration of Cabs5 or CaBs5 transgene. T2 population has also been tested for resistance/susceptible phenotypes (Figure 2,3). Similar to pepper, transgenic tomato lines containing Cabs5 showed a resistance phenotype, while those containing the susceptible CaBS5 allele exhibited susceptibility. No hypersensitive response or necrotic lesions were seen which coincided with previous observations of resistance in bs5 peppers. Per objective 4: Developed and conducted the first in a series of field trials in Florida and Ohio to better evaluate the impact of bacterial spot on production in order to develop a disease threshold model to evaluate cost-effectiveness of current and future bactericide programs.

    Publications

    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Rotondo, F. and Miller, S. A. 2017. Research Update  Xanthomonas. Specialty Crop Research Initiative project meeting, October 23, 2017, Tampa, Fl.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Rotondo, F., Moodispaw, M. R. and Miller, S. A. 2017. Tracking Xanthomonas gardneri infection of tomato fruits using an in vivo imaging system. 32nd Annual Tomato Disease Workshop, October 24, 2017, Tampa, FL. Poster.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Vrisman, C., M., Mera, J. and Miller, S. A. Demonstration - Hot water and chlorine seed treatments to eliminate bacterial plant pathogens. Mid-Ohio Growers Meeting, Mt. Hope, OH, January 12, 2017.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Testen, A. L. and Miller, S. A. Seedborne diseases and sanitation. Seed to Sustainability Workshop, Yellow Springs, OH, October 21, 2017.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Testen, A. L. and Miller, S. A. Seedborne diseases and sanitation. Seed to Sustainability Workshop, Watershed Sustainability Center, Cleveland, OH. November, 2017.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Miller, S. A., Mera, J. R., Saint-Preux, C. and Rotondo, F. 2017. Evaluation of fungicides and bactericides for the control of bacterial leaf spot of processing tomatoes, 2016. Plant Disease Management Reports 11:V113.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Jibrin MO, N Potnis, S Timilsina p, GV Minsavage, GE Vallad, PD Roberts, JB Jones, EM Goss (2018) Genome shuffling in a globalized bacterial plant pathogen: Recombination-mediated evolution in Xanthomonas euvesicatoria and X. perforans, Applied and Environmental Microbiology, doi:10.1128/AEM.00136-18.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Goss EM, Global movement, local consequences: Using population genomics to understand the changing landscape of plant pathogens,  Plenary session of the Annual Meeting of the American Phytopathological Society, San Antonio, TX, August 2017.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Iruegas-Bocardo F, XopJ6, a new member of the XopJ family of type III effectors in Xanthomonas perforans, International Congress of Plant Pathology 2018, Boston, MA, August 2018. Contributed poster.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Iruegas-Bocardo, F, Effector profile analysis of Xanthomonas perforans strains provides insights into the species evolution, First CONACYT Grant Holders Meeting in North America, Washington, DC, March 2018. Contributed abstract selected for talk.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Klein-Gordon J, Whole genome sequences reveal polymorphisms in bacteriocin genes of Xanthomonas perforans in Florida, American Phytopathological Society Annual Meeting, San Antonio, TX, August 2017. Contributed poster.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Timilsina S, Genomic fingerprinting and phylogenetic analyses of Xanthomonas perforans strains provide insights into bacterial evolution and global movement, American Phytopathological Society Annual Meeting, San Antonio, TX, August 2017. Contributed poster.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Timilsina S, Whole genome sequence analysis of Xanthomonas perforans shows widespread recombination events, International Congress of Plant Pathology 2018, Boston, MA, August 2018. Contributed poster.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Strayer A, Liao YY, Young M, Ritchie L, Vallad GE, Santra S, Freeman JH, Clark D, Jones JB, Paret ML. 2018. Advanced copper composites against copper-tolerant Xanthomonas perforans and tomato bacterial spot. Phytopathology 108(2): 196-205
    • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Paret ML, Strayer A, Liao YY, Young M, Ismail O, Averett D, Vallad G, Santra S, Tan W, Jones JB, Freeman JH. 2017. Copper nanomaterials against copper-tolerant strains of Xanthomonas perforans and bacterial spot of tomato. Florida Tomato Institute Proceedings. p 27-28
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Paret ML. Gordon Research Seminar at Nanoscale Science and Engineering for Agriculture and Food Systems Session, 2018 to highlight graduate students research findings on copper-composites (Invited)
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Paret ML. International IPM Symposium, Special Session on Nanomaterials in Agriculture, 2018 (Invited)
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Paret ML. Materials Sciences Society Annual Meeting, Special Session on Nanomaterials in Agriculture, 2018 (Invited)
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Paret ML. 2017. Tomato diseases and trial updates for North Florida and South Georgia region. Tomato Forum of the Gadsden County Tomato Growers Association, FL, December 7, 2017.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Paret ML. Development of advanced nano-materials and management of bacterial spot disease on tomato: findings from multi-year lab, greenhouse and field experiments in Florida. International Symposium on Agro-Bio Nanotechnology organized by the Center for Research in Applied Chemistry (CIQA), Government of Mexico, October 26, 2017 (Invited)
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Paret ML. Copper nanomaterials against copper-tolerant strains of Xanthomonas perforans and bacterial spot of tomato. Florida Tomato Committee Annual Meeting, September 8, 2017
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Huang, C-H and GE Vallad. 2018. Soil applications of acibenzolar-S-methyl induce defense gene expression in tomato plants against bacterial spot. European Journal of Plant Pathology 150:971-981.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Abrahamian, P, GE Vallad, S Timilsina, E Goss, and J Jones. 2017. From seed to fork: Advancing integrated practices for managing tomato bacterial spot. Proceedings from the 2017 Florida Tomato Institute, Naples, FL.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Kunwar, S., F. Iriarte, Q. Fan, E.E. da Silva, L. Ritchie, N.S. Nguyen, J.H. Freeman, R.E. Stall, J.B. Jones, G.V. Minsavage, J. Colee, J.W. Scott, G.E. Vallad, C. Zipfel, D. Horvath, J. Westwood, S.F. Hutton, and M.L. Paret. 2018. Transgenic Expression of EFR and Bs2 Genes for Field Management of Bacterial Wilt and Bacterial Spot of Tomato. Phytopathology 108:1402-1411.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Strayer-Scherer, A, YY Liao, M Young, L Ritchie, GE Vallad, S Santra, JH Freeman, D Clark, JB Jones, ML Paret. 2018. Advanced Copper Composites Against Copper-Tolerant Xanthomonas perforans and Tomato Bacterial Spot. Phytopathology 108:196-205.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Jibrin, MO, N Potnis, S Timilsina, GV Minsavage, GE Vallad, PD Roberts, JB Jones, and EM Goss. 2018. Genomic inference of recombination-mediated evolution in Xanthomonas euvesicatoria and X. perforans. Appl Environ Microbiol 84:e00136-18. https://doi.org/10.1128/AEM.00136-18.
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: Timilsina, S, GV Minsavage, J Preston, EA Newberry, ML Paret, EM Goss, JB Jones, and GE Vallad. 2018. Pseudomonas floridensis sp. nov., a bacterial pathogen isolated from tomato. International Journal of Systematic and Evolutionary Microbiology 68:64-70.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Timilsina, S, H Adkison, AL Testen, EA Newberry, SA Miller, ML Paret, GV Minsavage, EM Goss, JB Jones, and GE Vallad. 2017. A Novel Phylogroup of Pseudomonas cichorii Identified Following an Unusual Disease Outbreak on Tomato. Phytopathology 107:1298-1304.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Abrahamian, P., G. E. Vallad, R. Willis, H. Adkison, A. Wen. 2017. Evaluation of copper and biological compounds for managing bacterial spot of tomato, fall 2016. Plant Disease Management Reports 11:V016.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Abrahamian, P., G. E. Vallad, R. Willis, H. Adkison, A. Wen. 2017. Evaluation of copper and non-copper alternative compounds for managing bacterial spot of tomato, fall 2016. Plant Disease Management Reports 11:V085.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: G. Rajashekara; L. Deblais. International Tomato Diseases meeting, oral presentation (Malaga - Spain - August 2016)
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: G. Rajashekara; L. Deblais; V. Srivastava. OARDC conference, poster presentation (Wooster - Ohio  May 2018)
    • Type: Journal Articles Status: Submitted Year Published: 2018 Citation: G. Rajashekara; L. Deblais; V. Srivastava; C. Vrisman; D. Kathayat; Y. Helmy; G. Closs. Novel narrow spectrum small molecule growth inhibitors effective against Xanthomonas species (Phytopathology journal  submission by Fall 2018)
    • Type: Journal Articles Status: Published Year Published: 2018 Citation: D Liabeuf, SC Sim, DM Francis. 2018. Comparison of marker-based genomic estimated breeding values and phenotypic evaluation for selection of bacterial spot resistance in tomato. Phytopathology. 108(3):392-401.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Berdikul Qushim, Feng Wu, Zhengfei Guan, and Gary Vallad. Optimal Pest Management Decision under Risk: The Case of Tomato Disease Management. Accepted by the 2018 Agricultural & Applied Economics Association Annual Meeting, Washington, D.C., August 5-7
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Abrahamian, P., S. Timilsina, G.V. Minsavage, J.B. Jones, E.M. Goss, and G.E. Vallad. 2018. Characterizing the epidemiological link between transplant and field outbreaks of bacterial spot on tomato with whole genome sequencing. International Congress of Plant Pathology (ICPP) 2018, Boston, MA.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Klein-Gordon, J., E.M. Goss, J.B. Jones, G.E. Vallad. 2018. Assessing changes in Xanthomonas perforans populations in Florida based on a recent state-wide survey of commercial tomato fields: A work in progress. 33rd Annual Tomato Disease Workshop, Chincoteague Island, VA.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Timilsina, S., J. Pereira-Martin, G.V. Minsavage, P. Abrahamian, F. Iruegas-Bocardo, J.C. Huguet Tapia, E.A. Newberry, N. Potnis, G.E. Vallad, E.M. Goss, and J.B. Jones. 2018. Whole genome sequence analysis of Xanthomonas perforans shows widespread recombination events. International Congress of Plant Pathology (ICPP) 2018, Boston, MA.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Abrahamian, P., S. Timilsina, G. V. Minsavage, E. Goss, J.B. Jones, G.E. Vallad. 2017. Fitness and movement of Xanthomonas perforans and the effect of AvrBst on pathogenesis in tomato transplant production. 2017 Meeting of the Southern Division of the American Phytopathological Society, College Station, TX.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Abrahamian, P., S. Timilsina, G.V. Minsavage, N. Potnis, E. Goss, J.B. Jones, and G.E. Vallad. 2017. The type III effector AvrBst enhances Xanthomonas perforans fitness in tomato. 2017 Annual Meeting of the American Phytopathological Society, San Antonio, TX
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Timilsina, S., G.E. Vallad, E.M. Goss, and J.B. Jones. 2017. Whole genome sequencing of Xanthomonas perforans strains provides insights into bacterial evolution. 2017 Florida Phytopathological Society, Gainesville, FL.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Abrahamian, P., S. Timilsina, G.V. Minsavage, E.M. Goss, J.B. Jones, and G.E. Vallad. 2017. Xanthomonas perforans population dynamics and genetics from seedling to field-grown tomato. 32nd Annual Tomato Disease Workshop, Wimauma, FL.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Klein-Gordon, J.M., S. Timilsina, P. Abrahamian, G.V. Minsavage, N. Potnis, J.B. Jones, G.E. Vallad, and E.M. Goss. 2017. Whole genome sequences reveal polymorphisms in bacteriocin genes of Xanthomonas perforans in Florida. 2017 Annual Meeting of the American Phytopathological Society, San Antonio, TX.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Timilsina, S., P. Abrahamian, N. Potnis, G.V. Minsavage, F. Iruegas, J. Klein, F.F. White, B.J. Staskawicz, J.B. Jones, G.E. Vallad, E.M. Goss. 2017. Whole genome sequencing reveals rapid shifts in tomato bacterial spot populations in Florida. University of Florida, Emerging Pathogens Institute, Research Day, Gainesville, FL.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Timilsina, S., P. Abrahamian, F. Iruegas, G.V. Minsavage, B. Kolaczkowki, F.F. White, B.J. Staskawicz, G.E. Vallad, E.M. Goss, and J.B. Jones. 2017. Genomic fingerprinting and phylogenetic analyses of Xanthomonas perforans strains provide insights into bacterial evolution and global movement. 2017 Annual Meeting of the American Phytopathological Society, San Antonio, TX.
    • Type: Other Status: Published Year Published: 2018 Citation: Abrahamian, P. and Vallad, G.E. 2018. Clean tomato transplants: The first line of defense against bacterial spot. Berry/Vegetable Times. University of Florida, IFAS Extension. Summer 2018.
    • Type: Other Status: Published Year Published: 2018 Citation: Hutton, S.F., T.G. Lee and G.E. Vallad. 2018. Tomato variety improvement. In: Tomato Research Report 2017-2018. University of Florida, IFAS Research, p. 15-21.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Hutton, S.F., B. Staskawicz, A. Schultink, G.E. Vallad, J.B. Jones, and D. Horvath. 2018. Field control of bacterial spot through introduction of novel resistance alleles in tomato. Proceedings from the 2018 Florida Tomato Institute, Naples, FL.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Klein-Gordon, J., J.B. Jones, G.E. Vallad, and E.M. Goss. 2018. Assessing changes in Xanthomonas perforans populations in Florida based on a recent state-wide survey of commercial tomato fields: A work in progress. Proceedings from the 2018 Florida Tomato Institute, Naples, FL.
    • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Paret, M.L., Y.-Y. Liao, A. Strayer, J. Freeman, J.B. Jones, and G.E. Vallad. 2018. Field performance of nano magnesium oxide, a new antibacterial compound against bacterial spot of tomato. Proceedings from the 2018 Florida Tomato Institute, Naples, FL.
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Vallad, G.E. 2017. Current management options for bacterial spot on tomato (and Pepper). 2017 Southeast Regional Fruit & Vegetable Conference. Savannah, GA. (oral presentation)
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Vallad, G.E. 2017. Integrated bacterial spot management, a Florida perspective& The 49th Annual Meeting of the NC Tomato Growers Association, Asheville, NC. (oral presentation)
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Vallad, G.E. 2017. Integrated bacterial spot management, a Florida perspective. 2017 Great Lakes EXPO, Grand Rapids, MI (oral presentation)
    • Type: Other Status: Accepted Year Published: 2018 Citation: Abrahamian, P. and G.E. Vallad. 2018. Bacterial spot and target spot update. Lipman Grower Retreat, hosted by Lipman Produce, Immokalee, FL. (oral presentation)
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Vallad, G.E. 2018. Movement and management of tomato bacterial spot during seedling production. 34th Annual UF/IFAS Florida Seed Association, Gainesville, FL. (oral presentation)
    • Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Vallad, G.E. 2018. Engaging stakeholders on tomato and other vegetable disease projects: Lessons learned and opportunities. 2018 UF/IFAS Research Forum, Gainesville, FL. (oral presentation)
    • Type: Other Status: Accepted Year Published: 2018 Citation: Vallad, G.E. 2018. Common tomato diseases of Florida. Sumter County Master Gareners Training Meeting. Bushnell, FL. (oral presentation)
    • Type: Other Status: Accepted Year Published: 2017 Citation: Vallad, G. E. 2017. Research matters: GCREC vegetable pathology program. UF/IFAS Gulf Coast Research and Education Center Seminar Series, Balm, FL. (oral presentation)
    • Type: Other Status: Accepted Year Published: 2018 Citation: Vallad, G.E. 2018. Spring Vegetable Disease Update. 2018 Manatee County Spring Vegetable Industry Update, Ellenton, FL. (oral presentation)


    Progress 09/01/16 to 08/31/17

    Outputs
    Target Audience:Target audience during this reporting period include commercial vegetable growers, transplant operations, vegetable producers, seed company representatives, county extension agents, and researchers in plant pathology, plant-microbe interactions, and plant breeding. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?At the University of Florida, three graduate students and two post-doctoral scholars are working on Xanthomonas strain characterization, as well as tomato breeding aspects of the project.Theresearch group at Cornell is hosting a visiting scientist from China; and Drs. Mayton andYan received training on use of a confocal microscope. Post-docs and graduate students attended either or both the Tomato Disease Workshop or the Tomato Breeder's Roundtable. How have the results been disseminated to communities of interest?Some preliminary results were shared with growers and other stakeholders through grower and commodity meetings in Florida andOhio, and nationally at the 32nd Annual Toamto Disesae Workshop (Tampa, FL). What do you plan to do during the next reporting period to accomplish the goals?Per objective 1: Continue collection surveys andcharacterization of Xanthomonas strains from eastern US and from global collections. Conduct genome sequencing of representative strains. Per objective 2: Continue efforts to evaluate and nanomaterials in field trials and identified small molecules against diverse Xanthomonas strains. Develop infested seed to evaluate bactericidal seed treatments. Per objective 3: Continue breeding efforts with MAS and pyramiding transgenes into specific breeding lines. Per objective 4: Develop and continue collection of economic data related to tomato production.

    Impacts
    What was accomplished under these goals? Per objective 1:Conducted an extensive Florida collection of Xanthomonas strains from tomato in 2017 across growers and varieties. Collected 400+ strains that werecharacterized for race and species from Florida, S. Carolina, Indiana, Ohio, China, Thailand, and South East Asia. Generated genome sequences of 175 strains from tomato. (Sequenced strain breakdown: Florida: 67, North Carolina: 18, South Carolina: 17, Ohio: 16, Indiana: 16, Thailand: 21, China: 15, and South East Asia: 5). Characterized effector profiles of strains, showing variation in key effectors in the XopJ family, including AvrXv4 and AvrBsT.Identifiednew effector (XopJ6), widely distributed worldwide but new in US, likely involved in virulence on tomato.Established anassembly and analysis bioinformatics pipeline. Xanthomonas strains from China and Thailand were collected during separate visits by Vallad, Jones and Miller. Per objective 2: Evaluated advance nanoformulated copper composites in greenhouse and field trials.Screened 4,182 small molecules against X. gardneri and X. perforans identified a total of 1384 compounds as potential growth inhibitors (hits) of the Xanthomonas strains tested; out of which 8 small molecules were chosen for specificity to Xanthomonas, lack of phytotoxicity, and ability to reduce disease in planta. Per objective 3: Established three separate field locations for screening (resistance, cultural control, and chemical management) against X. gardneri, X. euvesicatoria (also referred to as T1 strains), and X. perforans. Developed inbred parent lines with at least two major genes (Rx3 and Rx4/Xv3) with QTL for resistance. We have developed detailed mapping information (including candidate gene identification for some of these) and linked markers for all. Demonstrated the use of marker assisted selection for specific genes and background genome selection for genetic background, utilizing amplicon-based sequencing approaches for genotyping that should drive costs below what is currently available through specific SNP assays (e.g. Competitive allele specific PCR, KASP). Leveraged germplasm developed for this project to assist colleagues in screening isolates collected from field epidemics. Per objective 4: Conducted tomato cost analysis. Costs associated with BST management practices include expenses on labor, fuel, equipment/machinery use, and pesticides. Evaluated efficacy, cost effectiveness and risk efficiency of different BST management practices using two season data of field trials in Florida.

    Publications


      Progress 09/01/15 to 08/31/16

      Outputs
      Target Audience:Target audience during this reporting period include commercial vegetable growers, transplant operations, vegetable producers, seed company representatives, county extension agents, and researchers in plant pathology, plant-microbe interactions, and plant breeding. Changes/Problems:Per objective 2: Underestimated the difficulties of obtaining infested seed lots from seed companies. The large quantities necessary to evaluate bactericidal compounds have forced us to generate infested seed. We will use several methods to generate infested seed. We will collectseed from infected fruit in bacterial spot field trials in Florida and Ohio. We will also use a vacuum infiltration methodand a pistil inoculation method to generate artificially contaminated seed; the former method should generate the highest levels of surface contamination while the later should generate higher levels of internally contaminated seed. Per objective 4: Co-PI Lewis Ivey recently relocated from Louissiana State University to The Ohio State University. Objectives originally listed for Louissiana will now be conducted in Ohio. We only expect a slight delay in activities as the Co-PI relocates and transfers the subaward. What opportunities for training and professional development has the project provided? 4 graduate students and 3 post-doc researchers are involved in the conduct of allaspects of this research, and to attend local, regional, and national meetings, including commodity meetings. Three one-week intensive hands-on workshops were conducted for students and practicing plant breeders in Wooster, OH including Session 1: Field Design and Analysis; Session 2: Marker Assisted Selection; Session 3: Genome Wide Analysis (May and June 2015). Target audience: graduate students and practicing professionals. How have the results been disseminated to communities of interest? In this period we have publications, presentations at conferences, workshops, and the eXtension.org "Plant Breeding and Genomics" community of practice as the main outreach methods. In 2016 we presented at National Association of Plant Breeders, the Tomato Breeders Roundtable and the Solanaceae Genome Workshop (13th Solanaceae Conference), American Phytopathological Society, 2015 Florida Ag Expo, Florida Seedsman Association,Mid-America Food Processors Association annual meeting, Tomato Disease Workshop, the International Symposium on Tomato Diseases, Plant Genome Engineering Symposium at UC Berkeley, and ASTA CSS & Seed Expo in Chicago, Illinois. These venues reached the broad array of academic and industry stakeholders, including a majority of the tomato crop-specific audience in the U.S. and beyond. Three one-week intensive hands-on workshops were conducted for students and practicing plant breeders in Wooster, OH including Session 1: Field Design and Analysis; Session 2: Marker Assisted Selection; Session 3: Genome Wide Analysis (May and June 2015). Target audience: graduate students and practicing professionals. Two workshops and field demonstrations during the Florida AgExpo educated growers about bacterial spot management. Additional information iscommunicated through the Plant Breeding and Genomics Community of Practice on eXtension.org. What do you plan to do during the next reporting period to accomplish the goals?For 2017 we are planning the following activities: Per objective 1: Collect additional international strains from Chile, China and Canada. Collect additional representative strains from North Carolina, Virginia, and Florida. Continue strain charcterization and sequencing efforts to examine global strain diversity, strain movement, and changes in effector profiles. Per objective 2: Complete the collection and detection of infested seeds from the first round of flower inoculations. Perform a second round of flower inoculations. Continue working with seed companies to identify contaminated seedlots for testing. GFP transformations of the X. perforans strains provided by Dr. Vallad (GEV872, GEV1001,GEV993, GEV839). Collection of new Xanthomonas strains from tomato greenhouses in Ohio. Continue characterization and testing of small molecules. Continue evaluating new Cu-composite compounds alone and in programsat NFREC and GCREC. Per objective 3: Continue mapping and breeding efforts to advance bacterial spot resistance, including non-blighting trait, specific to fresh market and processing industries. Construct bs5 mutants in the orthologous tomato gene by performing homologous recombination employing genome editing with CRISPR-Cas9. Field test CRISPR-Cas9 mutants in the tomato dmr6 gene and evaluate for disease resistance. Per objective 4: Continue to calculate revenue changes based on BST management practices identified in objectives 2. Collect economic information for processing tomato production in Ohio.

      Impacts
      What was accomplished under these goals? Per Objective 1: Visited seed production areas in Thailand and China, respectively. Out of 162 strains shipped from Thailand, selected37 strains. Preliminary characterization found that 3 strains are non-pathogenic, 30 are X. perforans race T3, and 4 strains are X. euvesicatoria race T1. Chose 22 representative strains for whole genome sequencing. Established collaborations to collect bacterial spot strains in Canada along Lake Ontario, to combine with strains from Ohio and Michigan. Received a collection of 35 Xanthomonas strains from Indiana and 44 strains from South Carolina. Additional sequencing determined the timing of recently observed changes in the effector profile of X. perforans using a historical collection of strains from Florida. The effector avrXv3 was present in race 3 strains with several independent mutations observed in race 4 strains. The effectors xopJ4 and avrBs2 were unchanged in all race 3 and race 4 strains. Strains collected after 2006 all carried avrBsT, which shared sequence identity with X. vesicatoria. Data suggest that xopJ4 and avrBsT are ideal targets for resistance breeding efforts. Conducted field trials determined the benefit of avrBsT to strain fitness. Per Objective 2: Developed three GFP- and two RFP-transformed X. gardneri strains, using strains from prior phylogenomic study. In vitro growth and pathogenicity of transformants compared to wild-type counterparts found no significant differences in in vitro growth. However, the RFP-transformants exhibited a slower in vitro growth rate compared to corresponding wild-types; although these strains still reached a similar culture saturation as wild-type within ~5h. Pathogenicity of the two GFP-transformants was similar to the respective wild type; evaluation of other transformed strains is in progress. Confirmed plasmid stability in vitro under non-selective conditions, and with growth in planta. Tomato blossoms inoculated with transformed X. gardneri and X. perforans strains in secured greenhouse locations. Inoculated 30 plants with a GFP-transformed X. gardneri strain, inoculated another 30 plants with a bioluminescent X. gardneri strain, and inoculated a third set of 30 plants with a GFP-transformed X. perforans strain. Performed additional flower inoculations of field-grown tomatoes using two natural Rifampicin-resistant X. perforans strains. In all cases, performed flower inoculations followed the methods described in Dutta et al. 2014. In greenhouse, between 30-50% of blossoms aborted after inoculation with transformed X. gardneri strains, while over 50% aborted following inoculation with transformed X. perforans strain. Out of 628 inoculated flowers on field-grown tomatoes, 256 aborted (41%) within 7 days; only 27 fruit (11%) persisted to harvest. Grouped small molecules based on seed coat permeability into three categories: permeable, selectively permeable and non-permeable. Determined that tomato seeds are selectively permeable; meaning that nonionic compounds can diffuse from the environment through the seed coat to the embryo, while ionic compounds are blocked. Identified a total of 51 tracers with 30 non-ionic fluorescent compounds representing 8 chemical families. Based on chemical-physical properties, coumarin compounds appeared suited for seed application and the best candidate compounds to date is coumarin 120 and coumarin 151. Determined the fluorescence emission and excitation spectra for candidates to quantify low levels of tracers with a fluorimeter. To quantify tracers, adapted the QuEChERS method for extraction and cleanup of samples from seed and plant tissues. Assessed several liquid media for ability to support Xanthomonas growth while not interfering with 96-well formatted plate reader assay used to screen small molecule library. Selected an MMX medium to screen 1040 small molecules, and identified numerous bacteriocidal and bacteriostatic compounds against X. perforans and X. gardneri. During the last year, developed three different Copper (Cu) based formulations, a Cu mixed-valence (Cu-MV) system with multiple Cu oxidation states, a Cu-Fixed-Quat material with Cu and quaternary ammonium infused within a silica matrix, and a Core-Shell Cu (Cu-CS) composite material with an inert particle coated with a Cu loaded silica gel shell. Conducted antimicrobial studies to determine the minimum inhibitory concentration (MIC), as well as in vitro activity against model plant pathogens Pseudomonas syringae pv. syringae, Clavibacter michiganensis subsp. michiganensis, Xanthomonas perforans. MIC values varied from materials and species tested with ranges 4 - 250 µg/mL metallic Cu, compared to MIC values 125- 500 µg/mL metallic Cu for copper hydroxide and copper sulfate (controls). Antimicrobial results demonstrated improved killing efficacy over the controls. Used a tomato seed germination and plant growth to determine phytotoxicity. Conducted 2 field trials at NFREC in Quincy, FL during fall 2015 and spring 2016, and a third field trial at GCREC in Wimauma, FL during the spring 2016 to evaluate the efficacy of Cu composites against bacterial spot. In the fall 2015 field trial at NFREC, only the MV-Cu statistically reduced bacterial spot severity based on AUDPC compared to the water-treated control (control), whereas all other treatments, including the copper-mancozeb standard, were statistically equivalent to the control. In the spring 2016 field trial at NFREC and GCREC, all Cu composite treatments were statistically equivalent to the standard copper treatments. However, all the Cu composites statistically reduced bacterial spot severity compared to the control at NFREC; whereas at GCREC, only the FQ-Cu, the low rate of CS-Cu, and high rate of MV-Cu provided significant reduction in disease severity compared to the control. None of the standard copper or Cu composite treatments statistically improved yield compared to the control. No phytotoxicity occurred in the trials. Per Objective 3: Field trials demonstrated the benefit of the non-blighting (NB) trait to suppress blighting associated with bacterial spot and target spot, and improve fungicide efficacy. Generated segregating mapping populations by crosses between susceptible and NB parents. Identified and selected NB and blighting segregants from several populations in the field for subsequent marker studies; advanced populations to BC1F4 generation. Screened over 300 tomato lines and accessions for resistance to X. gardneri in field trials and HR assays. Used a backcross breeding population derived from a cross between the resistant LA2533 with the susceptible tomato line OH2641 to map resistance to X. gardneri. Identified several QTL for resistance to X. gardneri, including a major QTL on chromosome 11. Screening of additional segregating populations narrowed resistance introgression to a 25 Mb region, breaking association between resistance and plant size. Fruit size is still lacking. Conducted CRISPR-Cas9 to mutangenize bs5 ortholog in tomato, generated homozygous mutants and introduced the pepper bs5 gene into tomato lines via Agrobacterium transformation. Tomato lines with bs5 reduced in planta growth of X. perforans by an order of magnitude. Isolated CRISPR-Cas9 mutants of the tomato dmr6 gene, and demonstrated resistance to both X. perforans and P. syringae pv. tomato infections. ?Per Objective 4: Estimated production costs for tomato in Florida to establish a benchmark of a non-treated control. Costs breakdown to specific cost components, including pre-harvest variable costs, pre-harvest fixed costs, and harvest and marketing costs. Collected costs of conventional fungicides. Identified changes of other inputs associated with specific treatments to estimate cost changes compared to non-treated control. Collected the past 10 years' weekly prices at 15 shipping points, and yield and acreage data (CA, FL, & national total) to calculate historical revenues.

      Publications

      • Type: Journal Articles Status: Accepted Year Published: 2016 Citation: Barak JD, Vancheva T, Lefeuvre P, Jones JB, Timilsina S, Minsavage GV, Vallad GE and Koebnik R(2016) Whole-genome sequence and analysis of Xanthomonas euvesicatoria strains and reassessment of the species. Front. Plant Sci. 7:1805. doi:10.3389/fpls.2016.01805
      • Type: Journal Articles Status: Published Year Published: 2016 Citation: Timilsina, S., Abrahamian, P., Potnis, N., Minsavage, G.V., White, F.F., Staskawicz, B.J., Jones, J.B., Vallad, G.E., and Goss, E.M. 2016. Analysis of sequenced genomes of Xanthomonas perforans identifies candidate targets for resistance breeding in tomato. Phytopathology 106:1097-1104.
      • Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: S. TIMILSINA, P. Abrahamian, N. Potnis, G. Minsavage, F. White, B. Staskawicz, J. Jones, G. Vallad, E. Goss. 2016. Whole genome sequencing of Xanthomonas perforans identifies effectors that influence breeding strategies. Annual meeting of the American Society of Phytopathology, Tampa, FL
      • Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: P. ABRAHAMIAN, J. Jones, G. Vallad. 2016. Evaluation of conventional and biological pesticides for managing tomato bacterial spot during transplant production. Annual meeting of the American Society of Phytopathology, Tampa, FL
      • Type: Theses/Dissertations Status: Accepted Year Published: 2016 Citation: Timilsina, S. 2016. Multi-Locus and Whole-Genome Sequence Analysis of Pseudomonads and Xanthomonads Impacting Tomato Production in Florida. University of Florida.
      • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Rotondo, F. and Miller, S. A. 2016. Development of green fluorescent protein-expressing Xanthomonas gardneri strains to study tomato infection processes. Phytopathology 106: S4.53.
      • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Plant Genome Engineering Symposium UC Berkeley May 31, 2016 Invited Speaker Genome Editing Approached to Develop Disease resistance in Plants
      • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: 5th International Symposium on Tomato Disease, Malaga, Spain June 13-16, 2016 Keynote Speaker Genomic Approaches for Creating Durable and Sustainable Disease Resistance
      • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Genomics-Enabled Accelerated Plant Breeding, Banbury Oct 16-19, 2016 Brian Staskawicz, UC Berkeley, Genome Editing in Plants.
      • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: 2016 Durable Wheat Resistance Meeting November 2-3, 2016 Keynote: Brian Staskawicz (University of California Berkeley, USA) "Genome Editing Approaches for Constructing Durable Disease Resistance"
      • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: ASTA CSS & Seed Expo 2016 Chicago, Illinois 05 Dec 2016 - 09 Dec 2016 Invited Speaker Genome Editing in Plants.
      • Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Strayer-Scherer A, Liao YY, Ocsoy I, Young M, Tan W, Santra S, Jones J, Paret ML. 2016. Advanced nanomaterials for management of bacterial spot of tomato. American Phytopathological Society Annual Meeting 2016 Abstracts.
      • Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2016 Citation: Strayer A, Ocsoy I, Liao YY, Paret ML, Jones JB, Tan W, Young M, Santra S, Freeman J, Olson SM, Ritchie L, Clark D. 2016. Recent advances in the development and evaluation of nanomaterials for management of bacterial spot of tomato. 5th International Symposium on Tomato Diseases Abstracts. Presented by Paret ML
      • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Young M, Santra S, Strayer A, Liao L, Paret ML, Jones JB. 2016. Development of advanced Cu formulations for combating Cu resistant plant pathogens. 5th International Symposium on Tomato Diseases Abstracts. Presented by Paret ML
      • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Paret ML. Organizer and Moderator, American Phytopathological Society Annual Meeting Special Session, 2016 Emerging Nano Materials for Disease Management and Pathogen Diagnostics.
      • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Bernal, Eduardo, Debora Liabeuf and David Francis, Evaluating Quantitative Trait Loci (QTL) Sources of Resistance in Tomato to Multiple Xanthomonas Spp. National Association of Plant Breeders Conference 2016, Raleigh, NC.