Source: PENNSYLVANIA STATE UNIVERSITY submitted to
ECOLOGICAL AND GENETIC DIVERSITY OF SOILBORNE PATHOGENS AND INDIGENOUS MICROFLORA
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0232500
Grant No.
(N/A)
Project No.
PEN04517
Proposal No.
(N/A)
Multistate No.
S-1053
Program Code
(N/A)
Project Start Date
Nov 1, 2012
Project End Date
Sep 30, 2017
Grant Year
(N/A)
Project Director
Jimenez Gasco, MA, DE.
Recipient Organization
PENNSYLVANIA STATE UNIVERSITY
208 MUELLER LABORATORY
UNIVERSITY PARK,PA 16802
Performing Department
Plant Pathology & Environmental Microbiology
Non Technical Summary
Soilborne diseases caused by plant pathogenic organisms result in major economic losses to agricultural production. These diseases pose a challenge to agriculture since they are difficult to control (chemical control is usually ineffective and many soilborne pathogens produce resting structures that survive in the soil for a long time) and may render soils unsuitable for production. Sustainable production systems must integrate disease management practices that incorporate disease resistance, nutrient enhancement, and biocontrol, among others, and must target a population of the pathogen and not a single individual. Pathogen populations may be very diverse, in particular regarding their virulence. Therefore, it is of key importance to understand the interactions between host genotypes, biocontrol agents and pathogen populations, within an ecological framework that includes resident and augmented microbial communities, and to integrate this information into disease management systems.
Animal Health Component
0%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2122410110260%
2154099110320%
2162410117020%
Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 215 - Biological Control of Pests Affecting Plants; 216 - Integrated Pest Management Systems;

Subject Of Investigation
4099 - Microorganisms, general/other; 2410 - Cross-commodity research--multiple crops;

Field Of Science
1103 - Other microbiology; 1102 - Mycology; 1170 - Epidemiology;
Goals / Objectives
Evaluate the population genetic diversity of soilborne pathogens and antagonistic microorganisms in different growing systems and regions using traditional and metagenomic approaches. Examine the effect of traditional or newly developed management strategies (chemical, cultural, and biological), soil physicochemical properties, or introduced biological control agents on the microbial community and its ability to suppress soilborne pathogens.
Project Methods
Objective 1. We will focus on various plant- and soil- associated microorganisms, both plant pathogenic and/or beneficial, such as Fusarium oxysporum, Verticillium dahliae, Bacillus spp. etc. Various techniques will be used to study and characterize diversity in microbial populations, such as sequencing of various conserved genes and other regions useful for species identification and phylogenetic relationships, microsatellite genotyping, single nucleotide polymorphism (SNP) genotyping or genotyping-by-sequencing (GBS) using next-generation sequencing platforms. These molecular techniques will be coupled with biological assays that include pathogenicity testing, measurement of plant colonization, biocontrol-associated activities such as chitinase or antibiotic production, phosphate solubilization, ISR, etc. Objective 2. This objective seeks to improve our understanding of microbial interactions (ecologic, metabolic, genomic) with different hosts used in rotations and colonization of the plant by pathogenic and nonpathogenic isolates. These include growth chamber, greenhouse and field experiments. We will study host-specificity or host-adaptation of non-pathogenic, plant-associated fungi (endophytes) and the interaction between pathogen populations and asymptomatic hosts grown in rotation with susceptible crops. Research will include efficacy of plant-associated microbes involved in plant growth promotion, disease suppression and/or nutrient sufficiency improvements when colonized plants are compared to non-colonized plants. Colonization will be determined at multiple dates, and in directly treated and non-treated plant parts. Disease will be assessed using both objective and subjective methods. Plant growth and yield will be determined when appropriate.

Progress 11/01/12 to 09/30/17

Outputs
Target Audience:Results of this project target the academic community in general, including general plant pathologists, diagnosticians, vegetable growers, population biologists and mycologists. Results are delivered through scientific publications, professional meetings and other gatherings, and consultation, both nationally and internationally. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided opportunities to train two Ph.D. students, one M.S. student and provided reserach opportunities for six undergraduate students. How have the results been disseminated to communities of interest?Results were disseminated to academic communities through scientific publications and presentations in professional societies (American Phytopathological Society). What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The emergence of plant pathogenicity in fungal populations is an intriguing matter for which we still do not have a clear understanding, and yet this may hold important clues to designing novel and more efficient practices to manage plant diseases. Plant pathogenic fungi often have complex ecological interactions with the niche being occupied, such as soil and plants. However, these interaction have been largely ignored by plant pathologists when not accompanied by disease. This is specially the case for two fungal species, Fusarium oxysporum and Verticillium dahliae. These fungi cause vascular wilts to hundreds of crop plants, but also have a complex endophytic biology. We studied the diversity of endophytic and pathogenic populations of F. oxysporum associated to banana in Ecuador. We used a multi-locus sequence method based on the translation elongation factor 1-alpha gene (TEF) and the intergenic spacer region of the ribosomal DNA (IGS), to characterize 300 isolates of F. oxysporum f.sp. cubense isolated from symptomatic 'Gros Michel' plants from the main banana-producing areas of Ecuador, as well as some F. oxysporum root endophytes. Our phylogenetic analyses placed all F. oxysporum f.sp. cubense isolates in a single clade associated to VCG0120. The presence of only one mating type (MAT1-2) confirms the clonal dispersion of the fungus within the country and its introduction in a single event, or several times but from a single source. In addition, a positive PCR reaction using specific primers for detection of Topical race 4 (TR4), corresponding pathogenicity and VCG analyses, revealed the presence of endophytic non-pathogenic isolates obtained from asymptomatic bananas that share genomic regions similar to those of TR4. This work provides new insights on the reliability and specificity of current quarantine-detection methods for TR4 and proposes the study of banana endophytes and their role in the emergence of pathogenicity. The highly virulent defoliating pathotype in V. dahliae has previously been shown to occur only in one clonal lineage (lineage 1A). By contrast, no clear association has yet been shown for race 1 with clonal lineages. Race 1 carries the effector gene Ave1 and is avirulent on hosts that carry resistance gene Ve1 or its homologues. The hypothesis tested was that race 1 arose once in a single clonal lineage, which might be expected if V. dahliae acquired Ave1 by horizontal gene transfer from plants, as hypothesized previously. In a diverse sample of 195 V. dahliae isolates from nine clonal lineages, all race 1 isolates were present only in lineage 2A. Conversely, all lineage 2A isolates displayed the race 1 phenotype. Moreover, 900-bp nucleotide sequences from Ave1 were identical among 27 lineage 2A isolates and identical to sequences from other V. dahliae race 1 isolates in Gen-Bank. The finding of race 1 in a single clonal lineage, with identical Ave1 sequences, is consistent with the hypothesis that race 1 arose once in V. dahliae. Molecular markers and virulence assays also confirmed the well-established finding that the defoliating pathotype is found only in lineage 1A. Pathogenicity assays indicated that cotton and olive isolates of the defoliating pathotype (lineage 1A) were highly virulent on cotton and olive, but had low virulence on tomato.

Publications

  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Jim�nez-D�az, R.M., Olivares-Garc�a, C., Trapero-Casas, J.L., Jim�nez-Gasco, M.M., Navas-Cort�s, J.A., Landa., B.B., and Milgroom, M.G. 2017. Variation of pathotypes and races and their correlations with clonal lineages in Verticillium dahliae. Plant Pathology 66: 651666.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2017 Citation: Rafiei, V., Banihashemi, Z., Jim�nez-D�az, R.M., Navas-Cort�s, J.A., Landa, B.B., Jim�nez-Gasco, M.M., Turgeon, B.G., and Milgroom, M.G. 2017. Comparison of genotyping by sequencing and microsatellite markers for unravelling population structure in the clonal fungus Verticillium dahliae. Plant Pathology DOI: 10.1111/ppa.12713.


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:This research is intended to fulfill the needs of U.S. agricultural producers for new methods targeting the management of soilborne diseases. Significant target audiences are scientists in research institutions and academia. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Results were disseminated to academic communities through scientific publications and presentations in professional societies (American Phytopathological Society). Results were also disseminated in the 12th International Verticillium Symposium held in Slovenia, October 6-9, 2016. What do you plan to do during the next reporting period to accomplish the goals?Research will continue to focus on various plant- and soil- associated microorganisms, both plant pathogenic and/or beneficial, such as Fusarium oxysporum and Verticillium dahliae in order to improve our understanding of microbial interactions with plants. Our ultimate goal is to design better disease management options (such as biocontrol agents, or efficient rotations) within an ecological framework.

Impacts
What was accomplished under these goals? The soilborne fungi Fusarium oxysporum and Verticillium dahliae cause vascular wilts as a result of vascular infection of a host plant and are amongst the most challenging diseases to manage. Some reasons for these management challenges are a gap on our understanding of their ecology in soil and as endophytic populations, and the lack of availability of molecular markers that resolve at the population level. We generated microsatellite markers for F. oxysporum and studied how these loci evolve in a haploid fungus. Most mutations could be fit to a stepwise mutation model, but a few appear to have involved multiple repeat units. No evidence of gene conversion was seen and some homoplastic numbers of repeat units were observed for these loci. We identified polymorphisms in the regions flanking the microsatellites that may provide better genetic markers for population genetics studies of these species. For studying Verticillium dahliae we used a population genomics approach to test the hypothesis of clonal expansion of a highly fit genotype. This fungal pathogen has a broad host range and can be dispersed in contaminated seed or other plant material. It has a highly clonal population structure, with several lineages having nearly worldwide distributions in agricultural crops. Isolates in lineage 1A are highly virulent and cause defoliation in cotton, okra, and olive (denoted 1A/D), whereas those in other lineages cause wilting but not defoliation (ND). Based on single nucleotide polymorphisms generated through genotyping-by-sequencing, phylogenetic and genealogical analyses resulted in five distinct subclades of 1A/D isolates that correlated closely with geographic origins in the Mediterranean basin, consistent with the hypothesis that the D pathotype was introduced at least five times in independent founder events into this region from a relatively diverse source population. The inferred ancestral haplotype was found in two isolates sampled before 1983 from the southwestern United States, which is consistent with historical records that 1A/D originated in North America.

Publications

  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Demers, J.E., and Jim�nez-Gasco, M.M. 2016. Evolution of nine microsatellite loci in the fungus Fusarium oxysporum. Journal of Molecular Evolution 82: 27-37.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Milgroom, M.G., Jim�nez-Gasco, M.M., Olivares-Garc�a, and Jim�nez-D�az, R.M. 2016. Clonal expansion and migration of a highly virulent, defoliating lineage of Verticillium dahliae. Phytopathology 106: 1038-1046.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Bautista-Jalon, L.S., Gugino, B. K., and Jim�nez-Gasco, M.M. 2015. Genetic diversity of Verticillium dahliae populations associated with symptomatic and asymptomatic hosts. 2016 Mid-Atlantic States Mycology Conference, State College, PA. April 22-24, 2016.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Jim�nez-Gasco, M.M. 2016. Advancing our understanding of Verticillium dahliae biology through genetic diversity and ecological research. 12th International Verticillium Symposium. Ljubljana, Slovenia. October 5-9, 2016.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Aynardi, B.A., Jim�nez-Gasco, M.M., and Uddin, W. 2016. Host adaptation and molecular detection of Sclerotinia homoeocarpa. Northeastern Plant, Pests, and Soils Conference, Philadelphia, PA. January 3-7, 2016.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Magdama, F., and Jim�nez-Gasco, M.M. 2016. The importance of endophytes in developing molecular detection methods: The case for race 4 of Fusarium oxysporum f. sp. cubense causing Panama disease on bananas. The 31st Annual Graduate Exhibition, The Pennsylvania State University, University Park, PA. March 18-20, 2016.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Magdama, F., and Jim�nez-Gasco, M.M. 2016. The importance of endophytes in developing molecular detection methods: The case for race 4 of Fusarium oxysporum f. sp. cubense causing Panama disease on bananas. The Gamma Sigma Delta Graduate Exhibition, The Pennsylvania State University, University Park, PA. March 29, 2016.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Magdama, F., and Jim�nez-Gasco, M.M. 2016. The importance of endophytes in developing molecular detection methods: The case for race 4 of Fusarium oxysporum f. sp. cubense causing Panama disease on bananas. 19th Annual Environmental Chemistry and Microbiology Student Symposium. The Pennsylvania State University, University Park, PA. April 8-9, 2016.


Progress 10/01/14 to 09/30/15

Outputs
Target Audience:This research is intended to fulfill the needs of U.S. agricultural producers for new methods targeting the management of soilborne diseases. Significant target audiences are scientists in research institutions and academia. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Two graduate students and three undergraduate students have been trained within the context of the research reported here. How have the results been disseminated to communities of interest?Results were disseminated to academic communities through scientific publications and presentations in professional societies (American Phytopathological Society). Results were also disseminated in the Common Bean Disease Workshop on Angular Leaf Spot and Root Rots held in Skukuza, South Africa, July 21, 2015. What do you plan to do during the next reporting period to accomplish the goals?Research will continue to focus on various plant- and soil- associated microorganisms, both plant pathogenic and/or beneficial, such as Fusarium oxysporum and Verticillium dahliae in order to improve our understanding of microbial interactions with plants. Our ultimate goal is to design better disease management options (such as biocontrol agents, or efficient rotations) within an ecological framework.

Impacts
What was accomplished under these goals? The soilborne fungus Fusarium oxysporum comprises host-specific pathogenic populations that cause vascular wilts as a result of vascular infection of a host plant. But it also comprises non-pathogenic populations that inhabit soil, and populations that can infect and colonize plants without causing disease, or endophytes. Overall, nonpathogenic populations of F. oxysporum have received very little attention. We studied populations of F. oxysporum associated with field-grown asymptomatic tomatoes, both endophytic and soil populations. Population diversity was studied using the DNA sequence of the translation elongation factor 1 alpha gene. A total of 26 sequence types was found, although two sequence types represented nearly two-thirds of the isolates studied. The population compositions differed between the two fields but not between soil samples within each field. A certain degree of differentiation was observed between populations associated with different tomato cultivars, suggesting that the host genotype may affect the composition of endophytic F. oxysporum populations. No clear patterns of genetic differentiation were observed between endophyte populations and soil populations, suggesting a lack of specialization of endophytic isolates. Overall, the large amount of diversity observed among these populations highlights the importance of nonpathogenic lifestyles to the biology of F. oxysporum. Both soil and endophyte populations were composed of many sequence types, even associated with just one plant. Some results were suggestive of specialization of endophytic populations, but generally, they support the hypothesis that most, if not all, F. oxysporum isolates are capable of living as endophytes. These endophytic and soil populations may represent a source of unstudied diversity within F. oxysporum. F. oxysporum is well known for its variety of agriculturally important characteristics, such as pathogenicity on many plant hosts; production of secondary metabolites, including mycotoxins; and biocontrol activity, and better exploration of endophytic and soil environments may discover even more economically or scientifically relevant traits.

Publications

  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Demers, J.E., Gugino, B. K., and Jim�nez-Gasco, M.M. 2015. Highly diverse endophytic and soil Fusarium oxysporum populations associated with field-grown tomato plants. Applied and Environmental Microbiology 81: 81-90.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Guo, L., Blatt, A.Z., Geiser, D.M., Jim�nez-Gasco, M.M., and Kuldau, G.A. 2015. Mating Type and Spore Killing Characterization of Fusarium verticillioides strains. Mycological Progress 14: 16.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Jim�nez-D�az, R.M., Castillo, P., Jim�nez-Gasco, M.M., Landa del Castillo, B.B., and Navas-Cort�s, J.A. 2015. Fusarium Wilt of Chickpeas: Biology, Ecology and Management. Crop Protection 73: 16-27.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Magdama, F., and Jim�nez-Gasco, M.M. 2015. Populations of Fusarium oxysporum f. sp. cubense causing Panama disease of banana in Ecuador: Learning from the past for future perspectives. American Phytopathological Society Annual Meeting, Pasadena, CA. August 1-5, 2015.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Jim�nez-Gasco, M.M. 2015. Diversity, ecology and evolution of soilborne fungal plant pathogens. Special Presentation. Page 13 in Book of Abstracts. Common Bean Disease Workshop on Angular Leaf Spot and Root Rots. Skukuza, South Africa. July 21, 2015.


Progress 10/01/13 to 09/30/14

Outputs
Target Audience: This research is directed towards fulfilling the needs of U.S. agricultural producers for new methods targeting the management of soilborne diseases. Significant target audiences are scientists in researcher institutions and academia. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Two graduate students and three undergraduate students have been trained within the context of the research reported here. How have the results been disseminated to communities of interest? Results were disseminated to academic communities through scientific publications and presentations in professional societies (American Phytopathological Society). Results were also disseminated in the II International Congress of Biotechnology and Biodiversity, held in Guayaquil, Ecuador, in June 2014. What do you plan to do during the next reporting period to accomplish the goals? Research will continue to focus on various plant- and soil- associated microorganisms, both plant pathogenic and/or beneficial, such as Fusarium oxysporum and Verticillium dahliae in order to improve our understanding of microbial interactions with plants. Our ultimate goal is to design better disease management options (such as biocontrol agents, or efficient rotations) within an ecological framework.

Impacts
What was accomplished under these goals? Verticillium wilts caused by the soilborne fungus Verticillium dahliae are among the most challenging diseases to control. Verticillium dahliae is a plant-pathogenic, ascomycete fungus with no known sexual stage and a highly clonal population structure. Populations of this pathogen have been traditionally studied by means of vegetative compatibility groups (VCGs) under the assumption that VCGs comprise genetically related isolates that correlate with clonal lineages. We aimed to resolve the phylogenetic relationships among VCGs and their subgroups based on sequences of the intergenic spacer region (IGS) of the ribosomal DNA and six anonymous polymorphic sequences containing singlenucleotide polymorphisms (VdSNPs). A collection of 68 V. dahliae isolates representing the main VCGs and subgroups (VCGs 1A, 1B, 2A, 2B, 3, 4A, 4B, and 6) from different geographic origins and hosts was analyzed using the seven DNA regions. Maximum parsimony phylogenies inferred from IGS and VdSNP sequences showed five and six distinct clades, respectively. Phylogenetic analyses of individual and combined data sets indicated that certain VCG subgroups (e.g., VCGs 1A and 1B) are closely related and share a common ancestor; however, other subgroups (e.g., VCG 4B) are more closely related to members of a different VCG (e.g., VCG 2A) than to subgroups of the same VCG (VCG 4B). Furthermore, MP analyses indicated that VCG 2B is polyphyletic, with isolates placed in at least three distinct phylogenetic lineages based on IGS sequences and two lineages based on VdSNP sequences. Results from our study suggest the existence of main VCG lineages that contain VCGs 1A and 1B; VCGs 2A and 4B; and VCG 4A, for which both phylogenies agree; and the existence of other VCGs or VCG subgroups that seem to be genetically heterogeneous or show discrepancies in their phylogenetic placement: VCG 2B, VCG 3, and VCG 6. These results raise important caveats regarding the interpretation of VCG analyses: genetic homogeneity and close evolutionary relationship between members of a VCG should not be assumed. The discrepancies in phylogenetic relationships among these VCG/clonal lineages may be explained by recombination. Genotyping by sequencing was conducted on 141 V. dahliae isolates representative of host, geographic origin, pathotype, and VCG. We genotyped 26,748 SNPs and detected 443 unique recombination events evenly distributed throughout the genome. Evidence of recombination was widespread among clonal lineages, with few recombinant haplotypes detected within clonal lineages. The extent and patterns of recombination observed suggest that clonal lineages arose by sexual reproduction. We hypothesize that the current clonal population structure in V. dahliae has arisen as a consequence of selection due to agriculture. This research indicates that recombination can potentially give rise to new clonal lineages and thereby increase genotypic diversity.

Publications

  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Testen, A.L., Jim�nez-Gasco, M.M., Ochoa, J.B., and Backman, P.A. 2014. Molecular detection of Peronospora variabilis in quinoa seeds and phylogeny of the quinoa downy mildew pathogen in South America and the United States. Phytopathology 104: 379-386.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Demers, J.E., Garz�n, C.D., and Jim�nez-Gasco, M.M. 2014. Striking genetic similarity between races of Fusarium oxysporum f. sp. ciceris confirms a monophyletic origin and clonal evolution of the chickpea vascular wilt pathogen. European Journal of Plant Pathology 139: 303-318
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Jim�nez-Gasco, M.M., Malcolm, G.M., Berbegal, M., Armengol, J., and Jim�nez-D�az, R.M. 2014. Complex molecular relationship between vegetative compatibility groups in Verticillium dahliae: VCGs do not always align with clonal lineages. Phytopathology 104: 650-659.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Milgroom, M.G., Jim�nez-Gasco, M.M., Olivares-Garc�a, C., Drott, M.T., and Jim�nez-D�az, R.M. 2014. Recombination between clonal lineages of the asexual fungus Verticillium dahliae detected by genotyping by sequencing. PLoS ONE 9(9): e1066740. doi: 10.1371/journal.pone.0106740.
  • Type: Books Status: Published Year Published: 2014 Citation: Kang, S., Demers, J., Jim�nez-Gasco, M. M., and Rep, M. 2014. Fusarium oxysporum. Chapter 5 in Genomics of Plant-Associated Fungi and Oomycetes: Dicot Pathogens. R. A. Dean, A. Lichens-Park, and K. Chittaranjan (Eds.). Pages 99-120. ISBN: 978-3-662-44055-1. Springer-Verlag Berlin Heidelberg.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Jim�nez-Gasco, M.M., Milgroom, M.G., Olivares-Garc�a, C., Drott, M.T., and Jim�nez-D�az, R.M. 2014. Genotyping-by-Sequencing sheds new light on the biology of Verticillium dahliae. Phytopathology 104(Suppl. 3):S3.153


Progress 11/01/12 to 09/30/13

Outputs
Target Audience: This research is directed towards the needs of the U.S. organic producer, and to other producers who want to diminish the use of pesticides. It also supports the international producer who cannot afford modern pesticides, where it provides an alternative that is frequently much less expensive. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Training sessions for international collaborators have been held in Ecuador and Bolivia, and several of these collaborators have traveled to Pennsylvania to learn new techniques, or to apply methods unavailable in their home countries. A visiting student from Spain was trained on population biology methods. How have the results been disseminated to communities of interest? We have repatriated all isolates to their countries of origin, so that this library of Bacillus species will be available for future uses. Presentations have been made to professional societies, and publications have been made in international journals. What do you plan to do during the next reporting period to accomplish the goals? Research is continuing on key crops, particularly in the areas of plant colonization and plant response when multiple beneficial organisms are applied at the same time.

Impacts
What was accomplished under these goals? Five hundred strains of plant colonizing bacteria were isolated in the US, Ecuador and Bolivia. Almost all of these were spore-forming bacteria from the genus Bacillus, or were closely associated with this genus. These isolates were indexed for multiple known beneficial attributes, such as phytohormone production, antibiotic production, chitinase production (ability to break down fungal cell walls and nematode eggs), as well as phosphatase and phytase production to convert non-available phosphorus to plant available forms. We are continuing to evaluate these isolates for plant colonization and positive plant responses such as induced systemic resistance to disease and improved nutritional status of the plant. Key colonization hosts are quinoa, common bean, and broad bean. The interaction between V. dahliae and oats is highly specialized; that is, only selected V. dahliae genotypes seems to be able to establish endophytic relationships with oats and possibly other monocots. We have genotyped over 100 V. dahliae isolates from a single field in PA growing in symptomatic and asymptomatic hosts. The potential dual role of V. dahliae, pathogenic on certain plants and endophytic on others, raises interesting questions about the biology, ecology, persistence, and spread of this fungus, which have important potential implications in the management of Verticillium wilts in agroecosystems.

Publications

  • Type: Journal Articles Status: Accepted Year Published: 2013 Citation: Testen A. L., M. Jimenez-Gasco J. B. Ochoa and P. A. Backman 2013. Molecular detection of Peronospora variabilis in quinoa seeds and phylogeny of the quinoa downy mildew pathogen in South America and the United States. Phytopathology 103.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Testen, A.L., McKemy, J.M., and Backman, P.A. 2013. First report of Passalora leafspot of quinoa caused by Passalora dubia in the United States. Plant Disease. 97(1):139.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Testen, A.L., J. M. McKemy, P.A. Backman 2013. First Report of Ascochyta Leaf Spot of Quinoa Caused by Ascochyta sp. in the United States. Plant Disease. 97(6):844 http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-11-12-1008-PDN
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: A. L. Testen, J. M. McKemy, and P. A. Backman. 2012. First Report of Quinoa Downy Mildew Caused by Peronospora variabilis in the United States. Plant Dis. 96:146.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: F. P. Poveda, J. B. OCHOA, E. Morillo & P. A. Backman 2012. Pathogenicity and disease development of tree tomato anthracnose in Ecuador. Proc. APS national meeting Providence RI. Phytopathology. 102: Supplement 4 No. 7, Poster no. 428-p.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Testen, A.L., Ochoa, J.B., Plata, G.R., Backman, P.A. 2012. Incidence and detection of Peronospora variabilis in quinoa seeds and plant tissue. Phytopathology. 102 S4.118. 2012 APS Annual Meeting, Providence, RI, Poster.
  • Type: Theses/Dissertations Status: Published Year Published: 2012 Citation: Testen, A. L. 2012. Microbial approaches to support Andean quinoa production. The Pennsylvania State University. M.S. thesis. 119 p.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Remesal, E., Landa, B.B., Jim�nez-Gasco, M.M. and Navas-Cort�s, J.A. 2013. Sequence variation of protein-coding genes as a diagnostic tool for the identification of Mycelial Compatibility Groups in Sclerotium rolfsii. Phytopathology. 104: 479-487.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Elmer, W.H., Useman, S., Schneider, R.W., Marra, R.E., LaMondia, J.A., Mendelssohn, I.A., Jim�nez-Gasco, M. M., and Caruso, F.L. 2013. Sudden Vegetation Dieback in Atlantic and Gulf Coast Salt Marshes. Feature Article. Plant Disease. 97: 436-445.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Malcolm, G. M., Kuldau, G. A., Gugino, B. K., and Jim�nez-Gasco, M. M. 2013. Letter to the Editor: Hidden host plant associations of soilborne fungal pathogens: An ecological perspective. Phytopathology. 103: 538-544.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Aynardi, B.A. Jimenez-Gasco, M.M., and Uddin, W. 2012. Molecular detection and host adaptation of Sclerotinia homoeocarpa, the causal agent of dollar spot of turfgrass. Phytopathology. 102:S4.7. American Phytopathological Society Annual Meeting, Providence, RI. August 4-6, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Demers, J., and Jimenez-Gasco, M.M. 2012. Are endophytic Fusarium oxysporum host adapted? Phytopathology. 102: S4.29. American Phytopathological Society Annual Meeting, Providence, RI. August 4-6, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Demers, J., Gugino, B.K. and Jimenez-Gasco, M.M. 2012. Diversity of endophytic Fusarium oxysporum populations in tomato: An ecological perspective. Phytopathology. 102: S4.29. American Phytopathological Society Annual Meeting, Providence, RI. August 4-6, 2012.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Jimenez-Gasco, M.M., and Malcolm, G.M. 2013. Hidden endophytic interactions between Verticillium dahliae and monocotyledonous hosts. Page 67 in Book of Abstracts. 11th International Verticillium Symposium, G�ttingen, Germany. May 5-8, 2013.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Jimenez-Gasco, M.M., Malcolm, G.M., L. Bautista-Jalon, and Gugino, B.K. 2013. Genetic differentiation between Verticillium dahliae populations from asymptomatic and symptomatic hosts. Phytopathology. 103 (Suppl. 2):S2.68. American Phytopathological Society Annual Meeting, Austin, TX. August 10-14, 2013.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Jimenez-Gasco, M.M., Demers, J.E., and Magdama, F. 2013. Possible infection of above-ground plant tissue by airborne conidia of nonpathogenic Fusarium oxysporum. Phytopathology. 103 (Suppl. 2):S2.68. American Phytopathological Society Annual Meeting, Austin, TX. August 10-14, 2013.
  • Type: Theses/Dissertations Status: Published Year Published: 2012 Citation: Jill Demers, "Evolutionary Ecology of Fusarium oxysporum-Plant interactions (PhD Dissertation, The Pennsylvania State University, August 2012).
  • Type: Book Chapters Status: Published Year Published: 2013 Citation: R.L. Melnick, B.A. Bailey, P.A.Backman. 2013. Bacterial Endophytes of Perennial Crops for Management of Plant Disease. pp 49-76 In: Bacteria in Agrobiology: Disease Management. D.K. Maheshwari Ed. Springer Books, Berlin Heidelberg.