Location: Plant Genetic Resources Conservation Unit
2023 Annual Report
Objectives
Objective 1. Optimize and implement best management practices to conserve, maintain, and distribute plant genetic resources and associated descriptive information.
Sub-objective 1.A. Optimize and implement best management practices based on the NPGS plan to conserve and maintain more than 100,000 accessions of priority plant genetic resources and their associated information.
Sub-objective 1.B. Distribute plant genetic resources and associated information to stakeholders, scientists, plant breeders, and educators.
Objective 2. Ensure accessibility, quality, and integrity of plant genetic resources through regeneration and conservation practices.
Sub-objective 2.A. Monitor and assess plant genetic resources for viability, trueness to type, vigor, and overall health.
Sub-objective 2.B. Conduct field and greenhouse regenerations of priority crops and their wild relatives based on low viability and low seed numbers to replenish and safeguard high quality plant genetic resources.
Objective 3. Conduct research to characterize and evaluate plant genetic resources for priority genetic, agronomic, nutritional, and health related traits.
Sub-objective 3.A. Characterize plant genetic resources using basic descriptors and other phenotypic data to describe useful agronomic and horticultural traits.
Sub-objective 3.B. Evaluate plant genetic resources using physiological, biochemical, and genetic techniques to determine seed quality, tolerances to biotic and abiotic stresses, and variations in nutritional and health related traits.
Approach
This project is part of a comprehensive nationwide program, the National Plant Germplasm System (NPGS), that conserves plant genetic resources for present and future crop improvement and related research activities. The project acquires, conserves, documents, distributes, characterizes, and evaluates the genetic resources of agronomic and horticultural crops including sorghum, peanut, peppers, watermelon, squash, eggplant, okra, sweetpotato, subtropical and tropical legumes, warm-season grasses, cowpeas, annual clovers, various industrial crops, other crops, and their wild relatives. All objectives and sub-objectives are non-hypothesis driven research as the mission is predominantly service oriented providing plant genetic resources and associated information to plant breeders and researchers for use in their scientific efforts. This project focuses on providing high quality, well-documented plant genetic resources and associated information to ARS, university, industry, and other research and education programs worldwide. The project investigators work closely with domestic and international scientists in helping them obtain the appropriate germplasm and information to achieve their research goals. Scientists remain current in all areas of research and education on each specific crop and their wild relatives through involvement with crop-specific Crop Germplasm Committees (CGC) and direct contact with scientists and educators who request plant genetic resources and information.
Progress Report
A large and highly diverse set of plant germplasm was preserved and distributed to scientists and plant breeders. A total of 104,831 accessions of 1,596 plant species representing 269 genera were maintained in the Griffin plant genetic resources collection. Over 88% of these accessions were available for distribution to users and over 94% were backed up securely at a second location. A total of 37,230 seed and clonal accessions were distributed upon request to scientists and educators worldwide this fiscal year as of July 13, 2022. Sorghum, cowpea, watermelon, and pepper were the most distributed crops. Clonal collections were continually maintained and distributed to stakeholders. Clonal collections include warm-season grasses, bamboo, Chinese water chestnut, perennial peanut, and sweet potato. Preservation methods include tissue culture, field plots, greenhouse plants, and hydroponics. Ten sweet potato accessions were provided to Fort Collins for cryo-preservation. A total of 2,550 accessions were sent to curators for regeneration. These activities ensure that the crop genetic resources at the Griffin location are safeguarded for future use to develop new cultivars and identify novel traits and uses in our food and fiber crops.
Regeneration Efforts:
ARS scientists in Griffin, Georgia harvested seed from 2022 peanut regeneration plantings were cleaned, counted, and submitted to seed storage for processing including 559 cultivated peanut accessions and 104 accessions of 29 wild peanut species which included 29 historic and 45 new accessions plus 30 other accessions to replenish old seed. Harvested seed from the 2022 Vigna regeneration were cleaned, counted, and submitted to seed storage for processing including 96 cowpea and 101 mung bean accessions. For the 2023 peanut and Vigna regeneration, 421 cultivated peanut and 36 Bambara groundnut accessions were planted in Byron; 50 wild peanut species accessions were planted in the greenhouse; and 25 Vigna accessions were planted in the screenhouse. An additional 30 cowpea accessions were planted by collaborators from Texas A&M AgriLife Research and 80 cowpea accessions by collaborators from University of Florida for regeneration.
Harvested vegetable seed from 2022 regenerations have been cleaned, counted, and submitted for processing including 50 okra, 120 watermelon, 80 cucurbits, and 420 peppers. Harvested vegetable seed from 2022 regeneration being prepared to submit for processing include 260 peppers, 70 okra, 80 squash, and 120 watermelon. Regenerations planned for this season include 582 pepper in Byron, Georgia and various vegetable crops via collaborations including watermelon, cucurbits, and okra.
Harvested seed from 2022 legume and warm-season grass regeneration plantings were cleaned, counted, and submitted to seed storage for processing including 15 sesame, 15 guar, 28 legumes, 34 grass, 14 legumes, and eight winged beans. Legume and warm-season grass regenerations scheduled for 2023 planting include 232 accessions consisting of 18 clover, 37 winged bean, 8 guar, 17 roselle, 11 castor bean, 50 warm season grass, 88 special-purpose legume, and 3 sesame accessions based on low viability or low seed numbers.
For sweet potato wild species regeneration, five accessions each were planted at Griffin and St. Croix. At St. Croix, all five accessions produced seed. In Griffin, only two accessions produced seed while one accession never flowered, and the other two accessions flowered but did not produce any seeds.
A total of 210 millet and 840 sorghum accessions were sent to St. Croix for regeneration and of these 193 millet and 837 sorghum accessions were harvested and submitted to seed storage for processing into the collection. An additional eight accession of wild sorghum species are currently growing in the greenhouse for regeneration as these species are difficult to germinate, produce seed, and to harvest. Species include Sorghum intrans, S. laxiflorum, S. macrospermum, S. plumosum, S. propinquum, S. stipoideum, S. versicolor, and Sorghum x almum.
Evaluation Efforts:
Based on screening of the USDA cultivated peanut germplasm collection, 200 accessions were selected to represent extremes of four traits including oil content, 100-seed weight, palmitic acid, and stearic acid (50 accessions per trait). These accessions were planted in Byron, Georgia in 2022. Seeds from 191 of these accessions were harvested and will be evaluated for these four traits in the lab this year. The same 200 accessions will be planted at Byron again in 2023. After two years’ experiments, the results will be reported and published. The main goal of this effort is to compare the results from screening the peanut seeds maintained in long term storage with freshly grown peanuts from the field.
In collaboration with University of Georgia researchers, 100 peanut wild species accessions were previously genotyped with a Single Nucleotide Polymorphism (SNP) array. These 100 accessions were planted in the screen house and fresh seeds (2 reps per accession) were collected in 2022. Seed quality including oil and protein content, fatty acid composition, and tocopherol will be measured this year. The newly collected seed quality trait data and SNP array data will be used for Genome Wide Association Mapping (GWAS).
Other biochemical characterizations of germplasm include measurement of seed oil content of eight clover accessions, galactomannans in 29 guar accessions, and fatty acids in 78 sesame lines. Research identifying variation for galactomannan content in guar is important for functional health food and supplement areas. Galactomannan is a natural source of soluble fiber beneficial to human health.
Ongoing collaborative peanut and cowpea evaluation projects include evaluation and identification of peanut smut resistance in the U.S. peanut mini-core collection with ARS collaborators from Stillwater, Oklahoma; development of a genetic catalog of USDA peanut germplasm collection in collaboration with researchers from the University of Georgia, Tifton, Georgia and HudsonAlpha Institute, Huntsville, Alabama; biological nitrogen fixation efficiency in cowpea with collaborators from Texas A&M AgriLife Research, Vernon, Texas; and seed mineral concentration in cowpea using GWAS and Genomic prediction tools with collaborators from Texas A&M AgriLife Research, Vernon, Texas.
Ongoing evaluation of vegetable germplasm includes research evaluating the effect of chemical agents used to inactivate plant viruses on seed viability and germination; characterizing the molecular basis for sex determination in a watermelon related dioecious species; investigation of capsaicin as extracted from pepper on induced hypothermia; and crop systematics and assessment of genetic diversity in the germplasm of several vegetable crops.
A non-funded cooperative agreement was established with Pride Road, LLC for the identification of seed and calyx production from nine roselle (Hibiscus sabdariffa) accessions originally selected from 28 tested roselle genotypes. Some of these may produce sufficient mature seed and be useful for jam, chutney, and tea products from calyces which will be developed by Pride Road, LLC. Also, the development of an ornamental roselle cultivar continued. This will be the 4th year of selections from an original mixed sample roselle genotype for ornate purple, red, and bronze foliage, and plant size.
Accomplishments
1. High oleic sesame. Seeds from select newly developed peanut and soybean varieties contain over 80% oleic acid which can extend the shelf-life time and benefit to human health. However, sesame seeds only contain about 40% oleic acid. ARS scientists in Griffin, Georgia, took two approaches to improve fatty acid composition in sesame. One was to screen the USDA sesame germplasm collection to identify accessions which have natural mutations for high oleic acid. The second was to chemically mutate elite lines to get high oleic acid. We took both approaches sequentially and produced mutant lines with approximately 75% oleic acid. These mutant lines will be very useful for breeders to develop improved sesame varieties and for scientists to use in further genetic studies.
Review Publications
Terrill, T., Courson, E.M., Morris, J.B., Morning, B.J., Owen, V.C., Muir, J.P., Cherry, N.M., Tonnis, B.D., Pech-Cervantes, A.A. 2023. Ticktrefoil (Desmodium) species as a nutraceutical forage resource for animals. Grassland Science. p. 1-7. https://doi.org/10.1111/grs.12411.
Wang, M.L., Tonnis, B.D., Li, X., Morris, J.B. 2023. Generation of sesame mutant population by mutagenesis and identification of high oleate mutants by GC analysis. Plants. 12(6). https://doi.org/10.3390/plants12061294.
