PHYSIOLOGY OF HERBICIDE RESISTANCE AND CHARACTERIZING THE GENETIC BASIS OF COMPETITIVE TRAITS IN WEEDS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1008720
• Project Start Date: Nov 13, 2015
• Project End Date: Oct 31, 2020
• Program Code: [(N/A)]- (N/A)

Recipient Organization
MISSISSIPPI STATE UNIV
(N/A)
MISSISSIPPI STATE,MS 39762

Performing Department
Plant & Soil Science

Non Technical Summary
Enhanced adaptation and mitigation of weeds is a growing threat to agriculture. Weeds, such as junglerice, have readily acquired resistance alleles and genetic mechanisms allowing them to sustain herbicide application, compete with the crop, and even mimic the crop. More interestingly, their abiotic stress response systems (drought tolerance, submergence, heat/temperature tolerance, etc.,) are often elite in comparison, because of longer periods of selection in the local environments. These genes, pathways, and expression networks and how these intersect are currently profound gaps in our understanding of how adaptive genetics of weed species intersects with environment and management practices. Improving crop production systems by tailoring the genetics of breeding germplasms for specific environments and studying the crop AND the surrounding weeds, is a sustainable solution to meet the growing challenges of agriculture and global sustainability.Because chemicals are highly effective in managing weeds, it has become the most popular option of weed control. However, with constant usage of herbicides in row crops, vegetable, and turf industry, very often these labeled herbicides cause significant injury on the crop itself, resulting in major yield loss. One of the good examples is tomato (Lypersicon esculentum), which is grown on over 444 acres across 627 farms in Mississippi (USDA, 2012), and although the crop is primarily grown in a plasticulture system (Pan et al., 1999), weeds are still a major problem in tomato production. Major weeds in tomato are yellow nutsedge, purple nutsedge, large crabgrass, and Palmer amaranth (Webster 2002). Among these weeds, yellow and purple nutsedge are the most problematic, causing significant yield losses and decreased fruit quality. Herbicide options in tomato are limited, and only a few are highly effective on nutsedge. These few herbicides that are labeled in tomato, show significant injury on the crop. Moreover, injury from herbicides drifted to greenhouse tomatoes leads to deformed fruits and yield reduction. Therefore, developing crops having tolerance to already labeled herbicides, and to herbicides that can potentially be drifted will improve quality and yield of the crop, and at the same time provide effective weed control.Row crops most commonly grown in Mississippi are cotton, soybean, corn, rice; while some commonly grown vegetables are tomato, sweet potato, and cucumber (USDA, 2012). In all of these crops, weed management has always been a major challenge to the growers. And with the introduction of herbicide-resistant crops technology, weeds are continuously exposed to selection pressure that results in weeds adapting to herbicide stress. Moreover, with the changing cropping systems that came along with the herbicide resistant technology, weeds have also found a way to adapt to the changes, thus rendering the herbicide-resistance technology ineffective. A survey conducted to determine how weed complexes have changed over time with change in management practices, showed that most of the weeds have evolved growth requirements and herbicide tolerances similar to the crop they infest (Loux and Berry 1991; McWhorter 1993). It would therefore be interesting to study how long the weeds take to evolve resistance to a particular herbicide. This will allow us to predict the time it takes herbicide-resistance technology to become ineffective since its commercialization. The objectives of the proposal will be to (1) develop a rapid assay to detect herbicide resistant weeds populations (non-destructive), identify mechanism of resistance, characterize competitive traits, biotic and biotic stress tolerance in weeds; (2) study the evolution of herbicide resistance in weeds; (3) develop herbicide tolerant crops.

Animal Health Component

70%

Research Effort Categories

Basic

20%

Applied

70%

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
201	2300	1020	40%
213	2300	1020	40%
203	2300	1020	20%

Knowledge Area
203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants; 201 - Plant Genome, Genetics, and Genetic Mechanisms; 213 - Weeds Affecting Plants;

Subject Of Investigation
2300 - Weeds;

Field Of Science
1020 - Physiology;

Keywords

herbicide resistance

plant breeding

weed competition

abiotic stress

biotic stress

genetic diversity

evolution

weeds

Goals / Objectives
The goal of this project is to study how long weeds take to evolve resistance to a particular herbicide, which will, in turn, allow us to predict the time it takes herbicide-resistance technology to become ineffective after its commercialization.The objectives of the proposal will be to (1) develop a rapid assay to detect herbicide resistant weeds populations (non-destructive), identify mechanism of resistance, characterize competitive traits, biotic and biotic stress tolerance in weeds; (2) study the evolution of herbicide resistance in weeds; and (3) develop herbicide tolerant crops.

Project Methods
Objective 1:Develop a fast assay to detect herbicide resistant weeds populations (non-destructive): Suspected herbicide resistant weeds will be collected from row crops, vegetable crops, or turfgrass. A set of allele-specific molecular markers for the herbicide resistant trait will be developed. These molecular markers can then be used for confirming resistance in any given weed sample from growers field, in less than a day, compared to the conventional greenhouse herbicide confirmation assay that takes at least 2 weeks.Characterize competitive traits in weeds, and abiotic and biotic stress tolerance in weeds: All abiotic stress treatments will be replicated three times, and conducted in glasshouses. Drought and submergence treatments will be evaluated by 100% submergence in water for 14 days, followed by a recovery period of 7 days. Appearance of new leaves and the recovery of injured leaves during the recovery period will be classified as submergence tolerance, otherwise sensitive. Drought stress will be imposed by withholding water for 7 days (30/21°C day/night), followed by recovery for 7 days. Appearance of new leaves and recovery of injured leaves during the recovery period will be classified as drought tolerant, otherwise sensitive. For heat tolerance screening, plants will be allowed to grow to the heading stage (30/21°C day/night), followed by high temperature stress at 40/31°C day/night. After 14 days of high temperature exposure, temperature will be decreased back to 30/21°C day/night and maintained until maturity. At maturity, the seed viability will be recorded, and the mean seed viability of three seedheads for each plant will be used to as an indicator of the level of heat tolerance of the plant. The rest of the vegetative and reproductive traits will be measured on plants that will be propagated in glasshouse. Photosynthetic efficiency: To measure the photosynthetic efficiency, two reading per leaf using a SPAD chlorophyll meter will be recorded on each leaf at 7 and 21 days after emergence (DAE). Shoot and root biomass will be measured at 21 DAE. Plant height, growth habit, flowering time, and seed yield, will be also be evaluated. For root length, and root area measurements, seeds from each accession will be surface sterilized, plated on MS medium (Murashige and Skoog, 1962) and placed in a controlled growth environment (30/21°C day/night). Plates will be sealed and placed vertically to allow roots to grow downwards along the surface of the media. High resolution images of the root will be captured on daily basis using a flatbed scanner. Root length and area will be analyzed using SmartRoot (Draye, 2008) form the scanned images of roots. Resistance to biotic stress will be determined by inoculating the growth media with microorganisms (Xanthomonas oryzae, and Magnaporthe grisea.) they are usually associated in the field. Disease symptoms will be recorded every other day for 21 days after inoculation. The resistance profile of each collected sample will be determined in high throughput, greenhouse bioassays using a total of 100 seedlings (25 per flat, 2 replications, conducted twice). Seedlings will be sprayed with the highest recommended rate of herbicide. Known resistant (R) and susceptible (S) accessions will be planted as reference and subjected to the same treatments. A nontreated check will be included. The number of surviving plants 21 d after treatment, and % visual injury rating of survivors will be recorded.Transcriptome profiles of weed ecotypes in response to abiotic and biotic stress: We will quantify gene expression profiles using RNAseq in selected ecotypes in response to biotic, and abiotic (including herbicide) stresses to identify stress related NTS genes and gene networks.Objective 2: Evolution of herbicide resistance in weedsSample collection: Weed populations will be collected from row crop fields and turfgrass across Mississippi. All samples from a field will represent a population. Plants will be sampled from fields having a history of recent herbicide resistant crop technology (Eg: glyphosate, glufosinate, dicamba, or 2,4-D application), and representing different rotation schemes (Eg: Cotton-Soybean-Cotton, Cotton-Corn-Cotton, Cotton monoculture).Recurrent herbicide selection and morphological characterization: Glasshouse experiments will be conducted with fifty seeds from each population sown in plastic trays containing commercial potting mix. At the six-leaf stage, herbicides will be applied individually at seven different rates representing suboptimal and high use rates. An untreated control will also be sprayed with water. Visual injury ratings will be taken 21 days after treatment (DAT). At flowering stage, morphological traits such as plant height, average leaf area and length, and photosynthetic efficiency, will be measured. Seeds will be harvested at maturity, and designated as the first generation populations. Seeds of these first generation populations will be sown in plastic trays and herbicide treatments will be repeated as above. Injury rating and morphological characteristics will be recorded as above, and mature seeds will be harvested and used for subsequent selection with herbicide, up to the fifth generation.Cross-resistance screening: At the end of the recurrent selection study, the fifth generation weed populations resistant to a particular herbicide will be tested for resistance to other herbicides, to determine if selection with one of the three herbicides, had selected for resistant to the other two herbicide. Populations will be tested at field-recommended rate of herbicides. Seeds will be sown as indicated in the recurrent herbicide selection study. At the six-leaf stage, herbicides will be applied, and injury rating taken at 21 DAT. Three replicate trays per treatment will be included.Objective 3: Developing herbicide tolerant cropsCrop (rice, cotton, tomato, etc.) varieties and/or lines representing modern and vintage cultivars, wild species, stress tolerant lines, introgression lines, and a commonly grown Mississippi cultivar, will be used. A combination of different herbicides will be tested at their recommended field rate on the selected lines. Initially, all the lines will be screened in the greenhouse for tolerance to the different herbicides. From this screen, only the four best lines (per highest herbicide tolerance, highest yield, and best fruit/grain quality), and the Mississippi cultivar, will be selected for use in the field study. Field studies will consist of herbicide treatments (including a nontreated control for comparison), arranged in randomized complete blocks with three replications, duplicated in the second year. Recorded data will include crop injury at 7 and 28 d after treatment (0 -100% scale), and changes in morphological characteristics such as plant height, leaf area, photosynthetic efficiency, fruit size, fruit shape, and marketable yield, all at 28 d post-treatment.QTL analysis will be conducted to determine molecular markers linked to herbicide tolerance in high-yielding crop lines selected from the phenotyping. At least 30 SSR/SNP markers will be used to screen the selected crop lines. DNA will be extracted from leaves and subjected to PCR to amplify the genetic regions associated with herbicide tolerance traits. Markers showing significant linkage with herbicide tolerance traits will be summarized and submitted to the online public database and made available to other researchers. Potential lines selected from the herbicide screening will be used in breeding experiments in the greenhouse to develop initial crop varieties with improved herbicide tolerance and high-yield potential. At the end of the second year, potential herbicide-tolerant and high-yielding crop varieties will be tested in a grower's field to confirm the results of the study.

Progress 11/13/15 to 10/31/20

Outputs
Target Audience:Target audiences: Current and future crop producers who require alternative and effective options of managing problematic weeds, especially herbicide resistant populations; researchers from academia and industry working in the field of weed sciences and herbicide resistance, this includes the students. Producers will require higher production costs to manage hard to control weeds to maintain economically-viable crop yields. Efforts: Meetings, conference, field day presentations to share outcomes of the project with researchers, Extension agents, growers, and industry representatives, within the weed science community. Changes/Problems:•Major problems or delays that may have a significant impact on the rate of expenditure: None •Significant deviations from research schedule or goals: None •Unexpected outcomes: None •Changes in approved protocols for the use or care of animals, human subjects, and/or biohazards encountered during the reporting period: None What opportunities for training and professional development has the project provided?Training activities: Training and mentoring of undergraduate and graduate students in weed identification, herbicide symptomology and calibration, in preparation for the annual regional/national Weed Contest. Course, PSS 8724 Herbicide Physiology and Biochemistry: The course helps students understand different aspects of plant and herbicide interaction, specifically in relation to weed management. It also cover applications of molecular biology techniques in agriculture for weed management, plant growth regulator and allelochemic chemistry, herbicide mode of action, and herbicide effects on plants and plant constituents. Course, PSS 8634 Environmental Fate of Herbicides: This course is designed to help the students better understand and address herbicide-related agronomic and environmental issues confronted by agricultural scientists. Professional development activities: Participated in the Weed Science Society of America (WSSA) Annual Meeting; and, Southern Weed Science Society Annual Meeting. Presentation at these meeting provided an opportunity to further develop presentation skills and to meet peers and faculty from around the country working in the field of herbicide/weed physiology. How have the results been disseminated to communities of interest?By presenting the outcomes of the project in WSSA, SWSS, ASPB, and MAS annual conference, thus reaching out to researchers, Extension agents, growers, and industry representatives, within the weed science, and plant science community. What do you plan to do during the next reporting period to accomplish the goals?Goal 1: Study the mechanisms and evolution of herbicide resistance in weeds and crops. Goal 2: Characterize and identify genomic regions associated with competitive traits (including biotic and biotic stress tolerance) in weeds. Goal 3: Identify new possibilities for sustainable weed management.

Impacts
What was accomplished under these goals? Goal 1: Develop a fast assay to detect herbicide resistant weed populations (non-destructive) Weedy rice: Standardized and developed a non-destructive Murashige and Skoog-agar plate assay to characterize and screen herbicide tolerant and susceptible, and allelopathic and non-allelopathic, weedy rice accessions. Developed in vitro assay to capture 3D images of weedy rice roots to determine root architectural traits associated with herbicide resistant phenotypes. Identify mechanism of resistance Tomato: Identified mechanism(s) of tolerance to auxin herbicides in selected tomato accessions. Cotton Identified 2,4-D tolerance in selected cotton chromosomal substitution lines. The next step is to identify the mechanism(s) of tolerance/resistance. Giant ragweed Identified mechanisms of resistant to glyphosate in selected giant ragweed biotypes. Characterize competitive traits in weeds Phenotyping Cotton chromosomal substitution lines - Auxin herbicide tolerance and allelopathy: We identified up to four cotton lines that have the ability to suppress problematic weeds in cotton production. Among numerous agronomic constraints of cotton production, weed interference has constantly been a major issue. In cotton, weeds cause several direct and/or indirect negative effects, such as (a) reducing fiber quality, (b) reducing crop yield, (c) increasing production costs, (d) reducing irrigation efficiency, and (e) serving as hosts and habitats for pests such as insects, rodents, nematodes, and disease-causing pathogens. Among problematic weeds, Palmer amaranth is the most prevalent in cotton grown in Mississippi, and is ranked as most troublesome in eight other states, primarily because of its aggressive growth habit and prolific seed production potential. Weed-suppressive cotton lines identified from this study will help control problematic weeds in cotton, curtail evolution of herbicide-resistant weeds, and will contribute to sustainable cotton production. Cotton lines identified by us can then be used in cotton breeding programs to develop cotton varieties with significant weed suppressive ability. Root system architecture and genes associated with allelopathy in weedy rice: Our preliminary study with a small subset of weedy rice accessions (10 accessions) identified 2 weedy rice accessions able to suppress barnyardgrass weed seedlings by causing more than 50% height reduction of barnyardgrass plants, and of these, one weedy rice accession caused greater than 75% height reduction. Weed management is often considered a leading factor limiting rice productivity, and among the weeds barnyardgrass is most damaging to rice causing up to 70% loss in rice grain yield. Allelopathy can therefore be bred into rice and act as a natural and sustainable weed control strategy. However, the extent to which weedy rice varieties exhibit superior competitive traits such as allelopathy is unknown, as are the genetic pathways potentially associated with allelopathy. Thus, there is a critical need to identify the specific allelopathic weedy rice accessions and the precise mechanisms through which these varieties are allelopathic. The likely consequences of leaving this need unmet will be further limitations in breeding efforts to enhance competitive vigor and yield of cultivated rice, ongoing economic burden for rice producers. The objective of this project is to (1) screen a diverse germplasm of weed rice to identify allelopathic phenotypes; (2) identify root system architectural changes (length, width, number, surface area, volume, emergence time, gravitropism response, number of root tips, circumnutation, etc.) associated with allelopathic phenotypes; and (3) use genome-wide association study to map root system architectural traits associated with allelopathy in weedy rice. The project will improve the production and economic sustainability of this vital crop. Identification and application of weed-suppressive tomato for weed management in tomato production: The Mississippi State University will provide effective control of problematic weeds in tomato production by developing weed suppressive tomato cultivars. The main goal of this project is to identify tomato varieties having the ability to suppress problematic weeds in tomato production. These tomato varieties will be tested in field to confirm effective suppression of weeds, and at the same time having high quality fruit and increased marketable yield. Results from this project will be made available to approximately 1,200 stakeholders at the Vegetable Field Day, ASHS and SWSS annual meetings, combined. The general tasks of the project will be to select tomato cultivars with the ability to suppress four most problematic weeds in tomato production; and, through further screenings and confirmation tests, select tomato accessions with weed suppressive ability, high yield and quality. The resulting tomato cultivars from this project will be made available to tomato growers across Mississippi through extension agents across the state. Sicklepod: Determined the localization and concentration of the anthraquinone in the sicklepod plant. Field trials were conducted in captive deer facility and research fields (R. R. Foil Plant Science Research Center, and at Andrew's Forestry and Wildlife Experiment station) to quantify deer and insect use and damage to soybeans in treatment and control plantings. Genomic regions associated with these competitive traits Tomato: Identified 6 SSR markers associated with tolerance to simulated rates of 2,4-D and dicamba Sicklepod Molecular markers identified to be tolerant to anthraquinone production. Cotton: Currently planning on conducting a QTL analysis to identify genomic regions associated with 2,4-D tolerance in selected cotton chromosomal substitution lines Abiotic and biotic stress tolerance in weeds Genomic regions associated with these stress related traits Weedy rice: Have conducted GBS of 70 weedy rice accessions, and currently conducting GWAS to identify genomic regions associated with each phenotype/trait. Goal 2: Evolution of herbicide resistance in weeds Tomato The genetic diversity of 20 herbicide-tolerant tomato lines selected from the herbicide tolerance screening was analyzed using 30 SSR markers commonly used in tomato genetic diversity studies. All 20 lines was clustered based on the estimated genetic distance, and the genetic diversity analysis was carried out based on the unweighted pair-group method using arithmetic average clustering and principal component analysis method. Giant ragweed: Determined the morphological diversity among six giant ragweed biotypes representing three states. Currently evaluating population structure of six giant ragweed populations (two susceptible and four resistant to glyphosate herbicide) using 15 microsatellite molecular markers. Weedy rice: Determined genetic diversity among and within herbicide tolerant and weed suppressive weedy rice populations. Goal 3: Developing herbicide tolerant crops Cotton tolerant to 2,4-D We have identified selected cotton lines, and are currently identify the mechanism(s) of resistance. Tomato tolerant to drift rates of dicamba We have identified selected tomato accessions tolerant to drift rates of dicamba, and are currently conducting crossing experiments in greenhouse to generate progeny to re-confirm tolerance.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Matte, W.D., R. S. Oliveira Jr, J. Constantin, R. R. Mendes, L. M. Padovese, and T. M. Tseng. 2020. Bioindicators selection to monitoring pyroxasulfone mobility and persistence in soil. Journal of Research in Weed Science (Accepted on December 2020). http://www.jrweedsci.com/article_119887.html
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Minaev, N., M. Tomaso-Peterson, T. C. Barickman, T. M. Tseng, D. Chesser, and J. D. McCurdy. 2020. Harvest Aids for Improved Bermudagrass Sod Shelf-Life. Agrosystems, Geosciences & Environment 3(1):e20108.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Yue, Z., and T. M. Tseng. 2020. Historical use of radioisotopes in weed research. In Radioisotopes in Weed Research (pp. 1-16). CRC Press.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Yue Z., T. M. Tseng, and N. Krishnan (2020) Antifeedant effect of sicklepod extract on soybean looper Chrysodeixis includens (Lepidoptera: Noctuidae). Mississippi Academy of Sciences Journal 65(3):293-300
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Zangoueinejad R., M. T. Alebrahim, and T. M. Tseng (2020) Molecular and Physiological Responses to Dicamba in Dicamba-Tolerant Wild Tomato. Mississippi Academy of Sciences Journal 65(3):358-374
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Zangoueinejad R., M. T. Alebrahim, and T. M. Tseng (2020) Absorption and translocation of dicamba in dicamba-tolerant wild tomato. Canadian Journal of Plant Sciences 0:0. https://doi.org/10.1139/CJPS-2019-0314
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Merritt L. H., J. C. Ferguson, A. E. Brown-Johnson, D. B. Reynolds, T. M. Tseng, and J. W. Lowe (2020) Reduced Herbicide Antagonism of Grass Weed Control through Spray Application Technique. Agronomy 10(8):1131. https://doi.org/10.3390/agronomy10081131
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Stallworth S., B. Schumaker, M. G. Fuller, and T. M. Tseng (2020) Consequences and Mitigation Strategies of Biotic and Abiotic Stress in Rice (Oryza sativa L.). In Plant Stress Physiology. IntechOpen. https://doi.org/10.5772/intechopen.91402
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Schumaker B., S. Stallworth, E. Castro, S. Shrestha, and T. M. Tseng (2020) Repeatable stair-step assay to access the allelopathic potential of weedy rice (Oryza sativa ssp.). Journal of Visualized Experiments e60764. https://doi.org/10.3791/60764
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Shrestha S., N. R. Burgos, and T. M. Tseng (2020) Competitive ability of weedy rice: toward breeding weed-suppressive rice cultivars. Journal of Crop Improvement 34(4):455-469. https://doi.org/10.1080/15427528.2020.1733158

Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Target audiences: Current and future crop producers who require alternative and effective options of managing problematic weeds, especially herbicide resistant populations; researchers from academia and industry working in the field of weed sciences and herbicide resistance, this includes the students. Producers will require higher production costs to manage hard to control weeds to maintain economically-viable crop yields. Efforts: Meetings, conference, field day presentations to share outcomes of the project with researchers, Extension agents, growers, and industry representatives, within the weed science community. Changes/Problems:•Major problems or delays that may have a significant impact on the rate of expenditure: None •Significant deviations from research schedule or goals: None •Unexpected outcomes: None •Changes in approved protocols for the use or care of animals, human subjects, and/or biohazards encountered during the reporting period: None What opportunities for training and professional development has the project provided?? Training activities: Training and mentoring of undergraduate and graduate students in weed identification, herbicide symptomology and calibration, in preparation for the annual regional/national Weed Contest. Course, PSS 8724 Herbicide Physiology and Biochemistry: The course helps students understand different aspects of plant and herbicide interaction, specifically in relation to weed management. It also cover applications of molecular biology techniques in agriculture for weed management, plant growth regulator and allelochemic chemistry, herbicide mode of action, and herbicide effects on plants and plant constituents. Course, PSS 8634 Environmental Fate of Herbicides: This course is designed to help the students better understand and address herbicide-related agronomic and environmental issues confronted by agricultural scientists. Professional development activities: Participated in the Weed Science Society of America (WSSA) Annual Meeting; and, Southern Weed Science Society Annual Meeting. Presentation at these meeting provided an opportunity to further develop presentation skills and to meet peers and faculty from around the country working in the field of herbicide/weed physiology. How have the results been disseminated to communities of interest? By presenting the outcomes of the project in WSSA, SWSS, ASPB, and MAS annual conference, thus reaching out to researchers, Extension agents, growers, and industry representatives, within the weed science, and plant science community. What do you plan to do during the next reporting period to accomplish the goals?Goal 1: Identify mechanism of resistance Identify mechanism of resistance to herbicides in weed rice. Characterize competitive traits in weeds Identify additional genomic regions associated with competitive traits in weedy rice (allelopathy, herbicide tolerance, submergence tolerance, heat/cold tolerance). Abiotic and biotic stress tolerance in weeds Identify genomic regions associated with abiotic stress (drought, heat, cold, submergence) in weedy rice. Goal 2: Evolution of herbicide resistance in weeds Determine genetic diversity among and within sweetpotato, tomato, weedy rice, and cotton. Goal 3: Developing herbicide tolerant crops Develop crosses between herbicide tolerant and commercial crop variety in greenhouse

Impacts
What was accomplished under these goals? Goal 1: Develop a fast assay to detect herbicide resistant weed populations (non-destructive) Weedy rice: Developed in vitro assay to capture 3D images of weedy rice roots to determine root architectural traits associated with herbicide resistant phenotypes. Identify mechanism of resistance Tomato: Identified mechanism(s) of tolerance to auxin herbicides in selected tomato accessions. Cotton Identified 2,4-D tolerance in selected cotton chromosomal substitution lines. The next step is to identify the mechanism(s) of tolerance/resistance. Characterize competitive traits in weeds Phenotyping Cotton chromosomal substitution lines - Auxin herbicide tolerance and allelopathy: We identified up to four cotton lines that have the ability to suppress problematic weeds in cotton production. Among numerous agronomic constraints of cotton production, weed interference has constantly been a major issue. In cotton, weeds cause several direct and/or indirect negative effects, such as (a) reducing fiber quality, (b) reducing crop yield, (c) increasing production costs, (d) reducing irrigation efficiency, and (e) serving as hosts and habitats for pests such as insects, rodents, nematodes, and disease-causing pathogens. Among problematic weeds, Palmer amaranth is the most prevalent in cotton grown in Mississippi, and is ranked as most troublesome in eight other states, primarily because of its aggressive growth habit and prolific seed production potential. Weed-suppressive cotton lines identified from this study will help control problematic weeds in cotton, curtail evolution of herbicide-resistant weeds, and will contribute to sustainable cotton production. Cotton lines identified by us can then be used in cotton breeding programs to develop cotton varieties with significant weed suppressive ability. Root system architecture and genes associated with allelopathy in weedy rice: The unique hardiness of weedy rice species allows them to thrive in dynamic and stressful environments. Weedy rice thrives because it has retained traits such as the potential to grow taller, produce more tillers, and consume more nutrients. These findings collectively suggest that weedy rice is an untapped source of novel genes for competitive traits that can be used in rice breeding programs, since they are of the same species as rice. One such trait is allelopathy, a process where the secondary metabolites produced by one plant species suppresses growth and development of neighboring species. Our preliminary study with a small subset of weedy rice accessions (10 accessions) identified 2 weedy rice accessions able to suppress barnyardgrass weed seedlings by causing more than 50% height reduction of barnyardgrass plants, and of these, one weedy rice accession caused greater than 75% height reduction. Weed management is often considered a leading factor limiting rice productivity, and among the weeds barnyardgrass is most damaging to rice causing up to 70% loss in rice grain yield. Allelopathy can therefore be bred into rice and act as a natural and sustainable weed control strategy. However, the extent to which weedy rice varieties exhibit superior competitive traits such as allelopathy is unknown, as are the genetic pathways potentially associated with allelopathy. Thus, there is a critical need to identify the specific allelopathic weedy rice accessions and the precise mechanisms through which these varieties are allelopathic. The likely consequences of leaving this need unmet will be further limitations in breeding efforts to enhance competitive vigor and yield of cultivated rice, ongoing economic burden for rice producers. The objective of this project is to (1) screen a diverse germplasm of weed rice to identify allelopathic phenotypes; (2) identify root system architectural changes (length, width, number, surface area, volume, emergence time, gravitropism response, number of root tips, circumnutation, etc.) associated with allelopathic phenotypes; and (3) use genome-wide association study to map root system architectural traits associated with allelopathy in weedy rice. The project will improve the production and economic sustainability of this vital crop. Identification and application of weed-suppressive tomato for weed management in tomato production: The Mississippi State University will provide effective control of problematic weeds in tomato production by developing weed suppressive tomato cultivars. The main goal of this project is to identify tomato varieties having the ability to suppress problematic weeds in tomato production. These tomato varieties will be tested in field to confirm effective suppression of weeds, and at the same time having high quality fruit and increased marketable yield. Results from this project will be made available to approximately 1,200 stakeholders at the Vegetable Field Day, ASHS and SWSS annual meetings, combined. The general tasks of the project will be to select tomato cultivars with the ability to suppress four most problematic weeds in tomato production; and, through further screenings and confirmation tests, select tomato accessions with weed suppressive ability, high yield and quality. The resulting tomato cultivars from this project will be made available to tomato growers across Mississippi through extension agents across the state. Sicklepod: Determined the localization and concentration of the anthraquinone in the sicklepod plant. Field trials were conducted in captive deer facility and research fields (R. R. Foil Plant Science Research Center, and at Andrew's Forestry and Wildlife Experiment station) to quantify deer and insect use and damage to soybeans in treatment and control plantings. Genomic regions associated with these competitive traits Cotton: Currently planning on conducting a QTL analysis to identify genomic regions associated with 2,4-D tolerance in selected cotton chromosomal substitution lines Abiotic and biotic stress tolerance in weeds Phenotyping Weedy rice: Screened 54 weedy rice and 15 rice accessions in greenhouse/growth chamber for weed suppressive potential, and tolerance to submergence, heat, and cold stress. Genomic regions associated with these stress related traits Weedy rice: Have conducted GBS of 70 weedy rice accessions, and currently conducting GWAS to identify genomic regions associated with each phenotype/trait. Goal 2: Evolution of herbicide resistance in weeds Weedy rice: Determined genetic diversity among and within herbicide tolerant and weed suppressive weedy rice populations. Goal 3: Developing herbicide tolerant crops Cotton tolerant to 2,4-D We have identified selected cotton lines, and are currently identify the mechanism(s) of resistance. Sweetpotato tolerant to glyphosate We have identified a sweetpotato population tolerant to field rate of glyphosate and are currently repeating the study to confirm the results. Tomato tolerant to drift rates of dicamba We have identified selected tomato accessions tolerant to drift rates of dicamba, and are currently conducting crossing experiments in greenhouse to generate progeny to re-confirm tolerance.

Publications

• Type: Book Chapters Status: Published Year Published: 2019 Citation: Shrestha, S., S. Stallworth, and T. M. Tseng (2019) Weedy Rice: Competitive Ability, Evolution, and Diversity. In Integrated View of Population Genetics. IntechOpen. http://doi.org/10.5772/intechopen.81838 (http://bit.ly/2FxqOE6)
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Werle I. S., A. Tucker, A. R. Ulguim, T. M. Tseng (2019) Methods for overcoming seed dormancy in Solanum americanum. In Proceedings of Mississippi Academy of Sciences  Summer Student Symposium, vol. 3.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Minaev N., J. D. McCurdy, C. Barickman, T. M. Tseng, M. Tomaso-Peterson, D. Chesser (2019) Fluxapyroxad and Pyraclostrobin Containing Fungicide Effects on Bermudagrass Transplantation Success Under Various Storage Conditions.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Schumaker B. C., T. M. Tseng, S. Shrestha and S. D. Stallworth (2019) Weedy Rice Genomic Regions Contributing to Allelopathy. In Proceedings of Weed Science Society of America, vol. 59, p. 297.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: De Castro E. B., C. A. Carbonari, F. H. Krenchinski, E. D. Velini, M. F. Dias and T. M. Tseng (2019) Effects of Day and Night Application of Glufosinate on Ammonia Accumulation, Electron Transport Rate, and Weed Control. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Schumaker B. C., T. M. Tseng, S. Shrestha and S. D. Stallworth (2019) Weedy Rice Genomic Regions Contributing to Allelopathy. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Small Z. D., J. D. McCurdy, J. T. Brosnan, J. D. Byrd, T. M. Tseng, E. Reasor and M. P. Richard (2019) Examining Environmental Factors and Chemical Control Options for Juncus Species. In Proceedings of Weed Science Society of America, vol. 59.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Stallworth S. D., T. M. Tseng and S. Shrestha (2019) Genetic Diversity and Molecular Markers for Abiotic Stress Tolerance in Weedy Rice. In Proceedings of Weed Science Society of America, vol. 59.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Zangoueinejad R., M. T. Alebrahim and T. M. Tseng (2019) Investigating Dicamba Uptake and Translocation in Dicamba-Tolerant Tomato Using HPLC. In Proceedings of Weed Science Society of America, vol. 59.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Yue Z., and T. M. Tseng and M. Lashley (2019) Sicklepod Extract as an Effective Deer Repellent: From Captive Facility to Field Testing. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Tucker A. P., B. C. Schumaker, S. Shrestha, S. D. Stallworth, N. R. Burgos and T. M. Tseng (2019) Root System Architecture and Genes Associated with Allelopathy in Weedy Rice. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Moraes C. P., E. Castro, S. Duarte, B. M. Silva, B. C. Schumaker, N. R. Burgos and T. M. Tseng (2019) Improved Herbicide Selectivity in Tomato by Safening Action of Benoxacor and Fenclorin. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Stallworth S. D., T. M. Tseng and S. Shrestha (2019) Genetic Diversity, Molecular Markers, and Genes for Abiotic Stress Tolerance in Weedy Rice. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Tseng T. M., B. C. Schumaker, N. R. Burgos, E. Castro, S. Shrestha and S. D. Stallworth (2019) Allelopathy in Weedy Rice: A Resource for Breeding Allelopathic Rice Cultivars. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Moraes C. P., E. Castro, S. Duarte, B. M. Silva, B. C. Schumaker, R. Snyder and T. M. Tseng (2019) Allelopathic Potential and Allelochemicals in Tomato: An Alternative for Sustainable Weed Management. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Silva B. M., E. Castro, S. Duarte, C. P. Moraes, B. C. Schumaker and T. M. Tseng (2019) Allelopathic Tomato: From Compounds to Molecular Markers. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Duarte S., E. Castro, B. M. Silva, C. P. Moraes, B. C. Schumaker and T. M. Tseng (2019) Benoxacor and Fenclorim Safeners for Protecting Tomato from Herbicide Injury: Screening and Mechanisms of Action. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Schumaker B. C., M. Ferreira, G.A. Caputo, S. Shrestha, S. L. Meyers, N. R. Burgos and T. M. Tseng (2019) Screening and development of markers for weed suppressive trait in sweet potato. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Zangoueinejad R., M. T. Alebrahim, S. Shrestha and T. M. Tseng (2019) Dose response study to evaluate dicamba tolerance of wild tomato germplasm. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Schumaker B. C., S. Shrestha, T. M. Tseng, N. R. Burgos, and S. D. Stallworth (2019) Genomics Regions Associated with Allelopathy in Weedy Rice. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Stallworth S. D., T. M. Tseng and B. C. Schumaker (2019) Screening Weedy Rice Germplasm for Tolerance to Various Abiotic Stresses. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Yue Z., and T. M. Tseng (2019) Preparation of Sickepod Extract with Potential Use as an Effective Deer Repellent. In Proceedings of Southern Weed Science Society, vol. 72.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Castro E. B., Moraes C. P., Duarte S., Burgos N. R., and T. M. Tseng (2019) Improved herbicide selectivity in tomato by safening action of benoxacor and fenclorim. (Submitted to Weed Technology on September, 2019)
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Barapour T., R. R. Hale, G. Kaur, B. Singh, T. M. Tseng, T. Wilkerson, C. D. Willett (2019) Weed Management Programs in Grain Sorghum (Sorghum bicolor). Agronomy 9(80):182. https://doi.org/10.3390/agriculture9080182
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Zangoueinejad R., M. T. Alebrahim, and T. M. Tseng (2019) Evaluation of auxin tolerance in selected tomato germplasm under greenhouse and field conditions. Weed Technology 33:1-8. https://doi.org/10.1017/wet.2019.51
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Zarrinabadi I. G., J. Razmjoo, A. A. Mashhadi, H. Karimmojeni H, T. M. Tseng (2019) Irrigation Effect On Yield And Desirable Metabolites Of Pot marigold (Calendula officinalis L.) Genotypes. Horticulture, Environment, and Biotechnology 60:467-478. https://doi.org/10.1007/s13580-019-00145-5
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Khakzad R., M. T. Alebrahim, A. Tobeh, M. Oveisi, R. Valiolahpor, and T. M. Tseng (2019) Effect of Different Management Practices on Portulaca oleracea Emergence in Soyabean. Weed Research 59:279 287. https://doi.org/10.1111/wre.12364
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Majd R., H. R. M. Chamanabad, E. Zand, M. Mohebodini, H. K. Khiavi, M. T. Alebrahim, T. M. Tseng (2019) Evaluation of herbicide treatments for control of wild gladiolus (Gladiolus segetum) in wheat. Applied Ecology and Environmental Research 17(3):5561-5570. http://dx.doi.org/10.15666/aeer/1703_55615570
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Tseng T. M., S. Shrestha, J. D. McCurdy, E. Wilson, and G. Sharma (2019) Target site mutation and fitness cost of acetolactate synthase-inhibitor resistant annual bluegrass (Poa annua). Hort Science 54(4):701-705.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Shrestha, S., G. Sharma, N. R. Burgos, and T. M. Tseng (2019) Response of Weedy rice (Oryza sativa) Germplasm from Arkansas to Glyphosate, Glufosinate and Flumioxazin. Weed Science 67:303-310. https://doi.org/10.1017/wsc.2018.92

Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Current and future crop producers who require alternative and effective options of managing problematic weeds, especially herbicide resistant populations; researchers from academia and industry working in the field of weed sciences and herbicide resistance, this includes the students. Producers will require higher production costs to manage hard to control weeds to maintain economically-viable crop yields. Efforts: Meetings, conference, field day presentations to share outcomes of the project with researchers, Extension agents, growers, and industry representatives, within the weed science community. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Training activities: Training and mentoring of undergraduate and graduate students in weed identification, herbicide symptomology and calibration, in preparation for the annual regional/national Weed Contest. Course, PSS 8724 Herbicide Physiology and Biochemistry: The course helps students understand different aspects of plant and herbicide interaction, specifically in relation to weed management. It also cover applications of molecular biology techniques in agriculture for weed management, plant growth regulator and allelochemic chemistry, herbicide mode of action, and herbicide effects on plants and plant constituents. Course, PSS 8634 Environmental Fate of Herbicides: This course is designed to help the students better understand and address herbicide-related agronomic and environmental issues confronted by agricultural scientists. Professional development activities: Participated in the Weed Science Society of America (WSSA) Annual Meeting on February, 2018; and, Southern Weed Science Society Annual Meeting on January, 2018. Presentation at these meeting provided an opportunity to further develop presentation skills and to meet peers and faculty from around the country working in the field of herbicide/weed physiology. How have the results been disseminated to communities of interest? By presenting the outcomes of the project in WSSA, SWSS, ASPB, and MAS annual conference, thus reaching out to researchers, Extension agents, growers, and industry representatives, within the weed science, and plant science community. What do you plan to do during the next reporting period to accomplish the goals?Goal 1: Identify mechanism of resistance Identify mechanism of resistance to herbicides in weed rice. Characterize competitive traits in weeds Identify additional genomic regions associated with competitive traits in weedy rice (allelopathy, herbicide tolerance, submergence tolerance, heat/cold tolerance). Abiotic and biotic stress tolerance in weeds Identify genomic regions associated with abiotic stress (drought, heat, cold, submergence) in weedy rice. Goal 2: Evolution of herbicide resistance in weeds Determine genetic diversity among and within the sweetpotato, tomato, weedy rice, and giant ragweed. Goal 3: Developing herbicide tolerant crops Develop crosses between herbicide tolerant and commercial tomato (susceptible) in greenhouse

Impacts
What was accomplished under these goals? Goal 1: Develop a fast assay to detect herbicide resistant weeds populations (non-destructive) Weedy rice: Standardized and developed a non-destructive Murashige and Skoog-agar plate assay to characterize and screen herbicide tolerant and susceptible, and allelopathic and non-allelopathic, weedy rice accessions. Developed in vitro assay to capture 3D images of weedy rice roots to determine root architectural traits associated with herbicide resistant phenotypes. Identify mechanism of resistance Tomato: Identified mechanism(s) of tolerance to auxin herbicides in selected tomato accessions. Giant ragweed Identified mechanisms of resistant to glyphosate in selected giant ragweed biotypes. Characterize competitive traits in weeds Phenotyping Annual bluegrass: Determined if resistance to ALS-inhibiting herbicide (foramsulfuron) resulted in fitness cost in annual bluegrass biotypes. Sweetpotato: Data from greenhouse and field experiments were similar, and at least 2 weed suppressive sweetpotato varieties were confirmed. Currently, the compound(s) in sweetpotato associated with weed suppression is being identified using chromatography techniques (HPLC). Sweetpotato quality from storage roots harvest from field experiment is being analyzed using HPLC. Sucrose, fructose, and glucose is being quantified from each treatment plots. Tomato: Initiated greenhouse screening of 51 tomato accessions for weed suppressive potential against Palmer amaranth. Tomato: Repeated field characterization of 10 highly tolerant tomato accessions for each herbicide was conducted at two locations, Truck Crops Branch Experiment Station, and, North MS Research and Extension Center. Sicklepod: Determined the localization and concentration of the anthraquinone in the sicklepod plant. Field trials were conducted in captive deer facility and research fields (R. R. Foil Plant Science Research Center, and at Andrew's Forestry and Wildlife Experiment station) to quantify deer and insect use and damage to soybeans in treatment and control plantings. Data is being analyzed. Genomic regions associated with these competitive traits Tomato: Identified 6 SSR markers associated with tolerance to simulated rates of 2,4-D and dicamba Sicklepod Molecular markers identified to be tolerant to anthraquinone production. Abiotic and biotic stress tolerance in weeds Phenotyping Weedy rice: Screened 54 weedy rice and 15 rice accessions in greenhouse/growth chamber for weed suppressive potential, and tolerance to herbicides, submergence, heat, cold, and drought stress. Genomic regions associated with these stress related traits Weedy rice: Have conducted GBS of 70 weedy rice accessions, and currently conducting GWAS to identify genomic regions associated with each phenotype/trait. Goal 2: Evolution of herbicide resistance in weeds Sweetpotato The genetic diversity of 31 sweetpotato varieties with varying weed suppressive potential was analyzed using 15 SSR markers commonly used in sweetpotato genetic diversity studies. Data is being analyzed. Tomato The genetic diversity of 20 herbicide-tolerant tomato lines selected from the herbicide tolerance screening was analyzed using 30 SSR markers commonly used in tomato genetic diversity studies. All 20 lines was clustered based on the estimated genetic distance, and the genetic diversity analysis was carried out based on the unweighted pair-group method using arithmetic average clustering and principal component analysis method. Giant ragweed: Determined the morphological diversity among six giant ragweed biotypes representing three states. Currently evaluating population structure of six giant ragweed populations (two susceptible and four resistant to glyphosate herbicide) using 15 microsatellite molecular markers. Weedy rice: Determined genetic diversity among and within herbicide tolerant and weed suppressive weedy rice populations. For this reporting period describe: Major activities completed: Identified mechanism of herbicide resistance in weeds (target-site mutation) Identified molecular markers associated with herbicide tolerance in plants. Identified plants with weed suppressive potential, herbicide tolerance, and submergence tolerance. Specific objectives met: Identified mechanism of resistance Characterized competitive traits in weeds Identified abiotic and biotic stress tolerance in weeds Determined the evolution of herbicide resistance in weeds Significant results achieved, including major findings, developments, or conclusions (both positive and negative): Weedy rice, differential tolerance to herbicides. Three of the 54 weedy rice accessions (B20, B2 and S11) had significantly higher tolerance to glyphosate with injury of less than 40%. Likewise, three weedy rice accessions (B49, B51 and S59) were found to have significantly higher tolerance to flumioxazin than others and these also had high recovery rate from the herbicide injury. These potential herbicide tolerant weedy relative of cultivated rice can be a used as a good genetic source for rice improvement program. Weedy rice, allelopathy. There was significant difference among the weedy rice accessions in terms of their weed suppressive potential (p< 0.0001). On an average, inhibition of barnyardgrass by weedy rice accessions was between 18% by S33, to 61% by B2. The accession B2 had significantly higher weed suppressive potential than other weedy rice accessions and allelopathic rice cultivars. Tomato, tolerance to simulated drift rates of herbicides. Numerous accessions were identified to be tolerant to herbicides tested; five to quinclorac, six to glyphosate, eight to dicamba, twelve to aminocycloparachlor, four to picloram, and four to aminopyralid. Markers TMS37, Tom 236-237, U81996 and SLR 21 were identified to be associated with tolerance in tomato to dicamba. There is on-going collaboration with federal (USDA-ARS) and academic (U. of Ark., Texas A&M, Clemson U., and NCSU) institutions on projects ranging from identifying cotton chromosomal substitution lines for allelopathy, to assessing threat of off-target auxin herbicides to US sweetpotato production systems. Key outcomes or other accomplishments realized: Allelopathic varieties identified in tomato, sweetpotato, and weedy rice will be used in systematic breeding program in greenhouse to generate offspring's having the allelopathic trait. Abiotic stress tolerant weedy rice identified will be further used in studying molecular mechanisms of stress tolerance so as to identify genetic regions associated with these stress tolerance. The efficacy of the sicklepod extracts will be compared with commercially available deer repellents in captive deer tests and in field research stations.

Publications

• Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Zangoueinejad R., M. T. Alebrahim, and T. M. Tseng (2019) Dose response study to evaluate dicamba tolerance in selected wild tomato germplasm. (Submitted to Weed Research on October, 2018)
• Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Zangoueinejad R., M. T. Alebrahim, and T. M. Tseng (2019) Absorption and translocation of dicamba in dicamba-tolerant wild tomato. (Submitted to Weed Biology & Management on November, 2018)
• Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Khakzad, R., M. T. Alebrahim, A. Tobeh, M. Oveisi, R. Valiolahpor, and T. M. Tseng (2018) Predicting Common Purslane (Portulaca oleracea) Emergence in Soybean Fields Using a Thermal Time Model under Various Management Operations. (Submitted to Weed Research on October, 2018)
• Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Shrestha S., N. R. Burgos, and T. M. Tseng (2018) Evaluating allelopathy in weedy rice: Step towards breeding weed suppressive rice cultivar. (Submitted to Weed Research on August, 2018)
• Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Zangoueinejad R., M. T. Alebrahim, and T. M. Tseng (2019) Evaluation of auxin tolerance in selected tomato germplasm under greenhouse and field conditions. (Submitted to Weed Technology on October, 2018)
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Bararpour T, R. R. Hale, G. Kaur, J. A. Bond, N. R. Burgos, T. M. Tseng, T. H. Wilkerson, and L. M. Lazaro (2018) Comparison of Herbicides for Control of Diclofop-Resistant Italian Ryegrass (Lolium perenne L. ssp. multiflorum) in Wheat. Agriculture, 8(9), 135. https://doi.org/10.3390/agriculture8090135
• Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Tseng T. M., N. R. Burgos, D. R. Gealy, S. Shrestha, and S. D. Stallworth (2018) Allelopathic potential of weedy rice: a step towards breeding weed suppressive rice cultivar. (Submitted to Weed Research on May, 2018)
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Begitschke, E.G., J.D. McCurdy, T.M. Tseng, T.C. Barickman, B.R. Stewart, C.M. Baldwin, M.P. Richard, and J.K. Ward (2018) Preemergence Herbicide Effects on Establishment and Tensile Strength of Sprigged Hybrid Bermudagrass. Agronomy 110, 1-7. http://doi:10.2134/agronj2017.12.0720
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Jervekani, M. T., H. Karimmojeni, J. Razmjoo, and T. M. Tseng (2018) Common sage (Salvia officinalis) tolerance to herbicides. Industrial Crops and Products, 121, 46-53. https://doi.org/10.1016/j.indcrop.2018.04.082
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Yue, Z.M., T. M. Tseng, and M. Lashley (2018) Characterization and Deer-Repellent Property of Chrysophanol and Emodin from Sicklepod Weed. American Journal of Plant Sciences, 9, 266- 280. https://doi.org/10.4236/ajps.2018.92022
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Tseng, T. M., V. K. Shivrain, A. Lawton-Rauh, and N. R. Burgos (2018) Dormancy-linked population structure of weedy rice (Oryza sativa). Weed Science, 66(3), 331-339. https://doi.org/10.1017/wsc.2017.86
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Begitschke, E. G., J. D. McCurdy, T. M. Tseng, T. C. Barickman, B. R. Stewart, C. M. Baldwin, M. P. Richard, and M. Tomaso-Peterson (2018) Preemergence Herbicide Effects on Hybrid Bermudagrass Root Architecture and Establishment. Hort Science 53:567-572. https://doi.org/10.21273/HORTSCI12480-17
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Rouse, C. E., N. R. Burgos, J. K. Norsworthy, T. M. Tseng, C. E. Starkey, and R. C. Scott (2018) Echinochloa Resistance to Herbicides Continues to Increase in Arkansas Rice Fields. Weed Technology 32, 34-44. https://doi.org/10.1017/wet.2017.82
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Kanapeckas, K. L., T. M. Tseng, C. C. Vigueira, A. Ortiz, W. C. Jr. Bridges, N. R. Burgos, A. J. Fischer, and A. Lawton-Rauh (2017) Contrasting Patterns of Variation in Weedy Traits and Unique Crop Features in Divergent Populations of US Weedy Rice (Oryza sativa sp.) in Arkansas and California. Pest management science, 74(6), 1404-1415. https://doi.org/10.1002/ps.4820
• Type: Book Chapters Status: Published Year Published: 2017 Citation: Alebrahim, M. T., R. Zangoueinejad and T. M. Tseng (2017) Biochemical and Molecular Knowledge about Developing Herbicide-Resistant Weeds. In Herbicide Resistance in Weeds and Crops. InTech
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Yue, Z., M. Lashley, and T. M. Tseng (2018) Evaluation of sicklepod extract as a natural deer repellent for food crops and vegetables. In Proceedings of ASA, CSSA and SSSA International Annual Meetings, vol. 153.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Yue Z., and T. M. Tseng (2018) Study of anthraquinone biosynthesis, transport and storage in sicklepod weed using fluorescence imaging. In Proceedings of Southern Weed Science Society, vol. 71.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Stallworth S., T. M. Tseng (2018) Phenotyping weedy rice (Oryza sativa) for the discovery of heat tolerance. In Proceedings of Southern Weed Science Society, vol. 71.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Tseng, T.M. (2018) From foes to friends: Exploiting the agricultural potential of weeds. Scientia Global https://doi.org/10.26320/SCIENTIA166
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Bararpour T, N. E. Korres, N. R. Burgos, R. R. Hale, and T. M. Tseng (2018) Performance of Pinoxaden on the Control of Diclofop-Resistant Italian Ryegrass (Lolium perenne L. ssp. multiflorum) in Winter Wheat. Agriculture, 8(7), 1-12. https://doi.org/10.3390/agriculture8070114
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Wilson D., G. A. Caputo, M. Ferreira, Z. Yue, C. Barickman, T. M. Tseng (2018) Molecular markers and compounds associated with sweetpotato allelopathy. In Proceedings of Southern Weed Science Society, vol. 71.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Shrestha S., S. Stallworth, N. R. Burgos, and T. M. Tseng (2018) Differential sensitivity of weedy rice accessions to glyphosate, glufosinate and flumioxazin. In Proceedings of Southern Weed Science Society, vol. 71.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Sharma G., T. M. Tseng, R. Snyder, and C. Barickman (2018) A step towards the development of herbicide tolerant tomatoes. In Proceedings of Southern Weed Science Society, vol. 71.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Stallworth S., and T. M. Tseng (2018) Screening competitive weedy rice germplasm for tolerance to submergence. In Proceedings of Southern Weed Science Society, vol. 71.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Caputo G. A., M. Ferreira, S. Shrestha, S. Meyer, and T. M. Tseng (2018) Screening of sweetpotato cultivars for allelopathic activity against weeds. In Proceedings of Southern Weed Science Society, vol. 71.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Yue Z., M. Lashley, S. Shrestha, G. Caputo, and T. M. Tseng (2018) Field testing of sicklepod extract as effective deer repellent to protect soybean. In Proceedings of Southern Weed Science Society, vol. 71.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2018 Citation: Tseng T. M. (2018) Virtual Reality in Weed Science Education. In Proceedings of Weed Science Society of America, vol. 58.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Current and future crop producers who require alternative and effective options of managing problematic weeds, especially herbicide resistant populations; researchers from academia and industry working in the field of weed sciences and herbicide resistance, this includes the students. Producers will require higher production costs to manage hard to control weeds to maintain economically-viable crop yields. Efforts: Meetings, conference, field day presentations to share outcomes of the project with researchers, Extension agents, growers, and industry representatives, within the weed science community. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Training activities: Training and mentoring of undergraduate and graduate students in weed identification, herbicide symptomology and calibration, in preparation for the annual regional/national Weed Contest. Weed nursery established will provide an opportunity to students, growers, Extension agents, and industry representatives, in enhancing their weed identification skills. Course, PSS 4633/6633 Weed Biology and Ecology: This course provides the student with basic understanding of the interrelationships between weed communities, their environment, human activity, and crop production; and, help identify selected weeds common in the southern region of the US. Course, PSS 8724 Herbicide Physiology and Biochemistry: The course helps students understand different aspects of plant and herbicide interaction, specifically in relation to weed management. It also cover applications of molecular biology techniques in agriculture for weed management, plant growth regulator and allelochemic chemistry, herbicide mode of action, and herbicide effects on plants and plant constituents. Course, PSS 8634 Environmental Fate of Herbicides: This course is designed to help the students better understand and address herbicide-related agronomic and environmental issues confronted by agricultural scientists. Professional development activities: Participated in the Weed Science Society of America (WSSA) Annual Meeting on February, 2017; and, Southern Weed Science Society Annual Meeting on January, 2017. Presentation at these meeting provided an opportunity to further develop presentation skills and to meet peers and faculty from around the country working in the field of herbicide/weed physiology. How have the results been disseminated to communities of interest? By presenting the outcomes of the project in WSSA, SWSS, ASPB, and MAS annual conference, thus reaching out to researchers, Extension agents, growers, and industry representatives, within the weed science, and plant science community. What do you plan to do during the next reporting period to accomplish the goals?Goal 1: Identify mechanism of resistance Determine if mechanism of resistance to ALS-inhibitor in annual bluegrass is due to enhanced metabolism and/or reduced translocation of the herbicide. Identify the mechanism of resistance to glyphosate in giant ragweed. Identify mechanism of resistance to herbicides in weed rice. Identify mechanism of resistance to glyphosate in St. Augustinegrass. Characterize competitive traits in weeds Identify additional genomic regions associated with competitive traits in weedy rice (allelopathy, herbicide tolerance, submergence tolerance, heat/cold tolerance). Abiotic and biotic stress tolerance in weeds Identify genomic regions associated with abiotic stress (drought, heat, cold, submergence) in weedy rice. Goal 2: Evolution of herbicide resistance in weeds Determine genetic diversity among and within the sweetpotato, tomato, weedy rice, and giant ragweed. Goal 3: Developing herbicide tolerant crops Repeat field characterization of herbicide tolerant tomato accessions to confirm results. Develop crosses between herbicide tolerant and commercial tomato (susceptible) in greenhouse

Impacts
What was accomplished under these goals? Goal 1: Annual bluegrass: Standardized and developed a non-destructive Murashige and Skoog-agar plate assay to characterize and screen herbicide resistant and susceptible annual bluegrass biotypes. Weedy rice: Standardized and developed a non-destructive Murashige and Skoog-agar plate assay to characterize and screen herbicide tolerant and susceptible, and allelopathic and non-allelopathic, weedy rice accessions. Identify mechanism of resistance Johnsongrass and Italian ryegrass: Identified mechanism of resistance (target site mutation) to ACCase-inhibiting herbicide (clethodim), in Johnsongrass and Italian ryegrass populations collected from Mississippi. Characterize competitive traits in weeds Sicklepod: Prepared different sicklepod extracts with high anthroquinone (potential deer repellent) content. Extracts were applied on soybean plants and tested for sensory preference of deer. Test was conducted at the Rusty Dawkins Memorial Deer Unit, Dept. of Wildlife, Fisheries & Aquaculture. Determined the localization and concentration of the anthraquinone in the sicklepod plant. Field trials were conducted in captive deer facility and research fields (R. R. Foil Plant Science Research Center, and at Andrew's Forestry and Wildlife Experiment station) to quantify deer and insect use and damage to soybeans in treatment and control plantings. Data is being analyzed. Tomato: Initiated greenhouse screening of 51 tomato accessions for weed suppressive potential against Palmer amaranth. Conducted screening of 120 tomato accessions for tolerance to simulated drift rates of 2,4-D , dicamba, glyphosate, quincloarc, aminopyralid, aminocycloparachlor and picloram. Identified numerous tomato accessions tolerant to each herbicide tested. Repeated field characterization of 10 highly tolerant tomato accessions for each herbicide was conducted at two locations, Truck Crops Branch Experiment Station, and, North MS Research and Extension Center. Sweetpotato: Conducted greenhouse screening of 31 sweetpotato varieties for weed suppressive potential against Palmer amaranth. Identified at least 4 weed suppressive sweetpotato varieties. Conducted field characterization of 18 sweetpotato varieties for allelopathic (weed suppressive) potential at the Pontotoc Ridge-Flatwoods Branch Experiment Station, Pontotoc, MS. Weed density was recorded every 2 weeks until sweetpotato harvest. Data from greenhouse and field experiments were similar, and at least 2 weed suppressive sweetpotato varieties were confirmed. Currently, the compound(s) in sweetpotato associated with weed suppression is being identified using chromatography techniques (HPLC). Sweetpotato quality from storage roots harvest from field experiment is being analyzed using HPLC. Sucrose, fructose, and glucose is being quantified from each treatment plots. Annual bluegrass: Determined if resistance to ALS-inhibiting herbicide (foramsulfuron) resulted in fitness cost in annual bluegrass biotypes. Genomic regions associated with these competitive traits Tomato: Identified 6 SSR markers associated with tolerance to simulated rates of 2,4-D and dicamba Abiotic and biotic stress tolerance in weeds Phenotyping Weedy rice: Screened 54 weedy rice and 15 rice accessions in greenhouse/growth chamber for weed suppressive potential, and tolerance to herbicides, submergence, heat, cold, and drought stress. Genomic regions associated with these stress related traits Goal 2: Evolution of herbicide resistance in weeds Sweetpotato The genetic diversity of 31 sweetpotato varieties with varying weed suppressive potential was analyzed using 15 SSR markers commonly used in sweetpotato genetic diversity studies. Data is being analyzed. Tomato The genetic diversity of 20 herbicide-tolerant tomato lines selected from the herbicide tolerance screening was analyzed using 30 SSR markers commonly used in tomato genetic diversity studies. All 20 lines was clustered based on the estimated genetic distance, and the genetic diversity analysis was carried out based on the unweighted pair-group method using arithmetic average clustering and principal component analysis method. Giant ragweed: Determined the morphological diversity among six giant ragweed biotypes representing three states. Currently evaluating population structure of six giant ragweed populations (two susceptible and four resistant to glyphosate herbicide) using 15 microsatellite molecular markers. Major activities completed: Identified mechanism of herbicide resistance in weeds (target-site mutation) Conducted morphological and phenological characterization of herbicide tolerant/resistant tomato, thus allowing us to associate certain morphological traits with herbicide tolerance/resistance. Identified sweetpotato varieties with weed suppressive potential. Identified molecular markers associated with herbicide tolerance in tomato. Identified weed rice accessions with weed suppressive potential, herbicide tolerance, and submergence tolerance. Specific objectives met: Identified mechanism of resistance Characterized competitive traits in weeds Identified abiotic and biotic stress tolerance in weeds Determined the evolution of herbicide resistance in weeds Significant results achieved, including major findings, developments, or conclusions (both positive and negative): Sweetpotato allelopathy From greenhouse screening we identified at least 4 sweetpotato varieties that were able to inhibit palmer amaranth weed up to 80%. From field experiment we identified at least 2 varieties that were able to inhibit native weed populations up to 50%. Tomato herbicide tolerance Field screening of herbicide tolerant tomato accessions show higher visual injury for the susceptible compared to tolerant accessions. Genetic diversity of 2,4-D and dicamba tolerant tomato accessions was significantly higher than susceptible accessions. Weedy rice abiotic stress tolerance Herbicide tolerance Red rice accessions showed differential response to glyphosate and there were many survivors from 1X rate of glyphosate. Control of the red rice using glyphosate present rate does not seem very effective. Blackhull accessions were found to be more competitive and aggressive than strawhull accessions, and may probably lead to higher yield loss when field are infested with blackhull accession. The tolerant accessions can be explored at molecular level to identify QTL'S associated with the trait using molecular markers. Submergence tolerance Five weedy rice accessions showed less than 20% stunting after submergence treatment. Drought tolerance Nine weedy rice accessions showed less than 20% stunting after drought stress treatment. Weedy rice allelopathy Allelloapthic potential of weedy red rice is found to be higher than cultivated rice and this information can be explored further to expand the rice gene pool. Potential accessions will be used in QTL analysis to identify genetic markers associated with allelopathy in the weedy rice and used in rice breeding program to develop weed suppressive rice cultivar. Ability of rice cultivars to suppress weeds will result in lesser herbicide usage and effective weed control, and therefore sustainable rice production. Sicklepod anti-herbivory property Field and greenhouse tests confirmed deer-repelling property of sicklepod extracts Deer-repelling compound was identified using HPLC. Key outcomes or other accomplishments realized: Allelopathic varieties identified in tomato, sweetpotato, and weedy rice will be used in systematic breeding program in greenhouse to generate offspring's having the allelopathic trait. Abiotic stress tolerant weedy rice identified will be further used in studying molecular mechanisms of stress tolerance so as to identify genetic regions associated with these stress tolerance. The efficacy of the sicklepod extracts will be compared with commercially available deer repellents in captive deer tests and in field research stations.

Publications

• Type: Journal Articles Status: Under Review Year Published: 2017 Citation: Jervekania, M. T., H. Karimmojeni, J. Razmjoo, and T. M. Tseng (2017) Biological Responses of Common Sage (Salvia Officinalis) to Five Light-Dependent Herbicides. (Submitted to Journal of Plant Biology on November, 2017)
• Type: Journal Articles Status: Under Review Year Published: 2017 Citation: Tseng, T. M., V. K. Shivrain, A. Lawton-Rauh, and N. R. Burgos (2017) Dormancy-linked population structure of weedy rice (Oryza sativa). (Submitted to Weed Science on October, 2017)
• Type: Journal Articles Status: Under Review Year Published: 2017 Citation: Rezaei, M., T. M. Tseng, and J. Razmjoo (2017) Differential morphological and physiological responses of four coneflower ecotypes to metribuzin herbicide. (Submitted to Pesticide Biochemistry and Physiology on September, 2017)
• Type: Journal Articles Status: Under Review Year Published: 2017 Citation: Yue, Z., T. M. Tseng, and M. Lashley (2017) Characterization of deer-repelling property of sicklepod. (Submitted to Crop Protection on October, 2017)
• Type: Journal Articles Status: Accepted Year Published: 2017 Citation: Kanapeckas K. L., T. M. Tseng, C. C. Vigueira, A. Ortiz, W. C. Jr. Bridges, N. R. Burgos, A. J. Fischer, A. Lawton-Rauh (2017) Contrasting Patterns of Variation in Weedy Traits and Unique Crop Features in Divergent Populations of US Weedy Rice (Oryza sativa sp.) in Arkansas and California. (Accepted in Pest Management Science on December, 2017).
• Type: Journal Articles Status: Accepted Year Published: 2017 Citation: Begitschke, E. G., J. D. McCurdy, T. M. Tseng, T. C. Barickman, B. R. Stewart, C. M. Baldwin, M. P. Richard, and M. Tomaso-Peterson (2017) Effects of Preemergence Herbicides on Hybrid Bermudagrass Root Growth and Morphology. (Accepted in Weed Technology on June, 2017)
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Nandula, V.K., G. Sharma, T.M. Tseng, and J. Bond (2017) Investigations into Suspected Clethodim-Resistant Johnsongrass and Italian Ryegrass from Mississippi. In Proceedings of Weed Science Society of America, vol. 57, p. 26.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Stallworth, S.D., S. Shrestha, and T.M. Tseng (2017) Characterization of Cold and Heat Tolerant Weedy Rice for Rice Improvement. In Proceedings of Southern Weed Science Society, vol. 70, p. 29.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Yue, Z., and T.M. Tseng (2017) Characterization of anthraquinones: A potential anti-herbivory compound in sicklepod. In Proceedings of Southern Weed Science Society, vol. 70, p. 43.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Shrestha, S., G. Sharma, and T.M. Tseng (2017) Screening and Characterization of Herbicide Tolerance among Weedy Rice Germplasm. In Proceedings of Southern Weed Science Society, vol. 70, p. 45.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Yates, H., G. Sharma, S.D. Stallworth, and T.M. Tseng (2017) Herbicide tolerant tomato: identifying molecular markers and determining the tolerance mechanisms. In Proceedings of Southern Weed Science Society, vol. 70, p. 45.
• Type: Journal Articles Status: Under Review Year Published: 2017 Citation: Shrestha, S., G. Sharma, N. R. Burgos, and T. M. Tseng (2017) Screening and Characterization of Glyphosate Tolerance among Weedy Rice Germplasm. (Submitted to Weed Technology on October, 2017)
• Type: Book Chapters Status: Published Year Published: 2017 Citation: Alebrahim, M. T., R. Zangoueinejad and T. M. Tseng (2017) Biochemical and Molecular Knowledge about Developing Herbicide-Resistant Weeds. In Herbicide Resistance in Weeds and Crops. InTech.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Tseng, T.M., E. Santos, V.K. Nandula, E.E. Wilson, G. Sharma, and J.D. McCurdy (2017) Fitness Costs and Mechanism of Acetolactate Synthase-inhibiting Herbicide Resistance in Annual Bluegrass. In Proceedings of Weed Science Society of America, vol. 57, p. 28.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Shrestha, S., and T.M. Tseng (2017) Screening and characterization of competitive traits among weedy rice germplasm. In Proceedings of Weed Science Society of America, vol. 57, p. 36.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Stallworth, S.D., S. Shrestha, and T.M. Tseng (2017) Phenotyping weedy rice for the discovery of drought and submergence tolerance for the improvement of cultivated rice. In Proceedings of Southern Weed Science Society, vol. 70, p. 10.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Yue, Z., and T.M. Tseng (2017) Tissue-specific distribution of anthraquinone compounds in sicklepod plants using fluorescence microscopy. In Proceedings of Southern Weed Science Society, vol. 70, p. 17.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Shrestha, S., and T.M. Tseng (2017) Exploring allelopathic potential of weedy rice: step towards breeding weed suppressive rice cultivar. In Proceedings of Southern Weed Science Society, vol. 70, p. 20.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Begitschke, E.G., J. McCurdy, T.M. Tseng, C. Baldwin, B. Stewart, C. Barickman (2017) Effects of Preemergence Herbicides on Sprigged Establishment of Hybrid Bermudagrass. In Proceedings of Southern Weed Science Society, vol. 70, p. 27.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Sharma, G., Z. Yue, E. Avila dos Santos, and T.M. Tseng (2017) Developing herbicide tolerant tomatoes: greenhouse screening to field characterization. In Proceedings of Southern Weed Science Society, vol. 70, p. 27.

Progress 11/13/15 to 09/30/16

Outputs
Target Audience:Target audiences: Current and future crop producers who require alternative and effective options of managing problematic weeds, especially herbicide resistant populations; researchers from academia and industry working in the field of weed sciences and herbicide resistance, this includes the students. Producers will require higher production costs to manage hard to control weeds to maintain economically-viable crop yields. Efforts: Meetings, conference, field day presentations to share outcomes of the project with researchers, Extension agents, growers, and industry representatives, within the weed science community. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Training activities: Training and mentoring of undergraduate and graduate students in weed identification, herbicide symptomology and calibration, in preparation for the annual regional/national Weed Contest. Wee nursery established will provide an opportunity to students, growers, Extension agents, and industry representatives, in enhancing their weed identification skills. Course, PSS 4633/6633 Weed Biology and Ecology: This course provides the student with basic understanding of the interrelationships between weed communities, their environment, human activity, and crop production; and, help identify selected weeds common in the southern region of the US. Course, PSS 8724 Herbicide Physiology and Biochemistry: The course helps students understand different aspects of plant and herbicide interaction, specifically in relation to weed management. It also cover applications of molecular biology techniques in agriculture for weed management, plant growth regulator and allelochemic chemistry, herbicide mode of action, and herbicide effects on plants and plant constituents. Course, PSS 8634 Environmental Fate of Herbicides: This course is designed to help the students better understand and address herbicide-related agronomic and environmental issues confronted by agricultural scientists. Professional development activities: Participated in the Weed Science Society of America (WSSA) Annual Meeting on February, 2016; and, Mississippi Academy of Sciences (MAS) Annual Meeting on February, 2016. Presentation at these meeting provided an opportunity to further develop presentation skills and to meet peers and faculty from around the country working in the field of herbicide/weed physiology. How have the results been disseminated to communities of interest?By presenting the outcomes of the project in WSSA and MAS annual conference, thus reaching out to researchers, Extension agents, growers, and industry representatives, within the weed science community. What do you plan to do during the next reporting period to accomplish the goals?Goal 1: Identify mechanism of resistance Determine if mechanism of resistance to ALS-inhibitor in annual bluegrass is due to enhanced metabolism and/or reduced translocation of the herbicide. Identify the mechanism of resistance to glyphosate in giant ragweed. Identify mechanism of resistance to herbicides in weed rice. Identify mechanism of resistance to glyphosate in St. Augustinegrass. Characterize competitive traits in weeds Identify additional genomic regions associated with competitive traits in weedy rice (allelopathy and herbicide tolerance). Abiotic and biotic stress tolerance in weeds Identify genomic regions associated with abiotic stress (drought, heat, cold, submergence) in weedy rice. Goal 2: Evolution of herbicide resistance in weeds Determine genetic diversity among and within the six giant ragweed biotypes. Goal 3: Developing herbicide tolerant crops Repeat field characterization of herbicide tolerant tomato accessions to confirm results. Develop crosses between herbicide tolerant and commercial tomato (susceptible) in greenhouse

Impacts
What was accomplished under these goals? Goal 1: Develop a fast assay to detect herbicide resistant weeds populations (non-destructive) Annual bluegrass: Standardized and developed a non-destructive Murashige and Skoog-agar plate assay to characterize and screen herbicide resistant and susceptible annual bluegrass biotypes. Weedy rice: Standardized and developed a non-destructive Murashige and Skoog-agar plate assay to characterize and screen herbicide tolerant and susceptible, and allelopathic and non-allelopathic, weedy rice accessions. Identify mechanism of resistance Annual bluegrass: Identified mechanism of resistance (target site mutation) to ALS-inhibiting herbicide (foramsulfuron), in annual bluegrass populations collected from Mississippi. Giant ragweed: Identified the mechanism of resistance to glyphosate in giant ragweed biotypes collected from MS, TN, and OH. Characterize competitive traits in weeds Phenotyping Tomato: Conducted screening of 120 tomato accessions for tolerance to simulated drift rates of 2,4-D , dicamba, glyphosate, quincloarc, aminopyralid, aminocycloparachlor and picloram. Identified numerous tomato accessions tolerant to each herbicide tested. Field characterization of 10 highly tolerant tomato accessions for each herbicide was conducted at two locations, Truck Crops Branch Experiment Station, and, North MS Research and Extension Center. Giant ragweed: Determined the morphological diversity among six giant ragweed biotypes representing three states. St. Augustinegrass: Identified glyphosate tolerant St. Augustinegrass lines, after screening 47 diverse lines of St. Augustinegrass. Weedy rice: Screened 54 weedy rice and 15 rice accessions in greenhouse for weed suppressive potential, and herbicide tolerance. Sicklepod: Prepared different sicklepod extracts with high anthroquinone (potential deer repellent) content. Extracts were applied on soybean plants and tested for sensory preference of deer. Test was conducted at the Rusty Dawkins Memorial Deer Unit, Dept. of Wildlife, Fisheries & Aquaculture. Determined the localization and concentration of the anthraquinone in the sicklepod plant. Genomic regions associated with these competitive traits Tomato: Identified 6 SSR markers associated with tolerance to simulated rates of 2,4-D and dicamba Abiotic and biotic stress tolerance in weeds Phenotyping Weedy rice: Screened 54 weedy rice and 15 rice accessions in greenhouse/growth chamber for tolerance to submergence, heat, cold, and drought stress Genomic regions associated with these stress related traits Goal 2: Evolution of herbicide resistance in weeds Tomato The genetic diversity of 20 herbicide-tolerant tomato lines selected from the herbicide tolerance screening was analyzed using 30 SSR markers commonly used in tomato genetic diversity studies. All 20 lines was clustered based on the estimated genetic distance, and the genetic diversity analysis was carried out based on the unweighted pair-group method using arithmetic average clustering and principal component analysis method. For this reporting period describe: Major activities completed: Developed rapid non-destructive plate assay to screen and characterize herbicide tolerant weeds. Identified mechanism of herbicide resistance in weeds (target-site mutation) Conducted morphological and phenological characterization of herbicide tolerant/resistant tomato and giant ragweed, thus allowing us to associate certain morphological traits with herbicide tolerance/resistance. Determine genetic diversity of herbicide tolerant tomato populations. Identified molecular markers associated with herbicide tolerance in tomato. Specific objectives met: Developed a fast assay to detect herbicide resistant weeds populations (non-destructive) Determined the evolution of herbicide resistance in weeds Significant results achieved, including major findings, developments, or conclusions (both positive and negative): Rapid non-destructive screening of herbicide tolerance identified three ALS-inhibitor resistant and one susceptible biotype of annual bluegrass. The root and shoot lengths of susceptible biotype was significantly shorter than the three resistant biotypes. Field screening of herbicide tolerant tomato accessions show higher visual injury for the susceptible compared to tolerant accessions. Genetic diversity of 2,4-D and dicamba tolerant tomato accessions was significantly higher than susceptible accessions. Key outcomes or other accomplishments realized: Rapid non-destructive screening of herbicide tolerant weeds allowed faster and more precise screening for herbicide tolerance/resistance. The screening also provided additional information on the root characteristics, and how these may be different between tolerant/resistant and susceptible plants. Morphological traits were found to be associated with herbicide tolerance in tomato, thus allowing tomato breeders in selecting accessions with herbicide tolerance. Genetic diversity data indicates higher diversity among and within herbicide tolerant tomato as compared to susceptible accessions. Higher genetic diversity may allow a population to evolve faster and develop tolerance to abiotic stresses, including chemical stress.

Publications

• Type: Journal Articles Status: Under Review Year Published: 2016 Citation: Kanapeckas K. L., T. M. Tseng, C. C. Vigueira, A. Ortiz, W. C. Jr. Bridges, N. R. Burgos, A. J. Fischer, A. Lawton-Rauh (2016) De-domestication of a weedy rice population directly from rice involves both crop mimicry and weedy escape traits. (Submitted to Rice Journal on September, 2016).
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Sharma G., and T.M. Tseng (2016) Identifying Molecular Markers Associated with Herbicide Tolerance in Tomato. In Proceedings of Weed Science Society of America, vol. 56, p. 15.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Walker J.C., T.M. Tseng, D.B. Reynolds, and D.R. Shaw (2016) Glyphosate Resistant Giant Ragweed (Ambrosia trifida): Phenotypic Variation, Genotypic Diversity, and Resistance Mechanisms. In Proceedings of Weed Science Society of America, vol. 56, p. 21.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Chan A.N., T.M. Tseng, H.W. Philley, C.M. Baldwin, and J. McCurdy (2016) St. Augustinegrass (Stenotaphrum secundatum) Germplasm Collection: Breeding for Glyphosate Tolerance and Population Structure. In Proceedings of Weed Science Society of America, vol. 56, p. 32.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Sharma G., and T.M. Tseng (2016) Genetic Diversity, Population Structure and Marker-herbicide Tolerance Trait Association of a Diverse Tomato Germplasm. In Proceedings of Weed Science Society of America, vol. 56, p. 45.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Wilson E.E., B. Jones, E. Santos, J. McCurdy, and T.M. Tseng (2016) Resistance to Acetolactate-synthase (ALS) Inhibitor in Annual Bluegrass (Poa annua): Mechanisms and Rapid Detection Techniques. In Proceedings of Weed Science Society of America, vol. 56, p. 70.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Tseng T.M., Wilson E.E., J. McCurdy, and (2016) Rapid Plate Assay for Detection and Characterization of Herbicide-Resistant Weeds. In Proceedings of Mississippi Academy of Sciences vol. 18, p. 29.