Location: Vegetable Crops Research
2022 Annual Report
Objectives
Objective 1: Efficiently and effectively acquire genetic resources of potato and its wild relatives, maintain their safety, genetic integrity, health and viability, and distribute them and associated information worldwide.
Objective 2: Develop more effective genetic resource acquisition, maintenance, evaluation, and/or characterization methods and apply them to priority genetic resources of potato and its wild relatives. Record and disseminate evaluation and characterization data and digital images via GRIN-Global and other data sources.
Objective 3: With other NPGS genebanks and Crop Germplasm Committees, develop, update, document, and implement best management practices and Crop Vulnerability Statements for potato genetic resource and information management.
Approach
Proven methods and developing needs and technologies will guide the most efficient acquisition of germplasm. Similarly, we will classify the germplasm by assigning species names, and also using other methods to identify pools of diversity useful to germplasm users. Preservation will be accomplished by keeping propagules as botanical seeds and in vitro clones. Optimal storage environments will be used. Germplasm health will be preserved by testing both seed increase parents and offspring for the seed-transmitted viroid, Potato Spindle Tuber Viroid (PSTV). Germplasm will be distributed to requesters in a timely fashion and stocks provided to federal, state, corporate, and private clients in the US and abroad at little to no cost. Data management will be done by staff at the genebank in cooperation with the national computer network for the nation’s germplasm, GRIN. DNA marker data analysis, experimental design, and interpretation will be done by staff on campus. We will make annual collecting trips to the southwest in the fall to collect subject material for DNA marker analysis for various aspects of interest with respect genetic richness and the relationship of diversity in the wild with that in the genebank. Core subsets and populations rich in unique alleles will be identified. Techniques that improve flowering, seedset, and germination useful to both the genebank and germplasm users will be studied. Outreach will be accomplished through the Potato Crop Germplasm Committee (PCGC), Plant Germplasm Operations Committee (PGOC), National Research Support Program – 6 (NRSP6), Germplasm Resources Information Network (GRIN-Global), and by maintaining the genebank website covering all aspects of the project mission.
Progress Report
We completed or made good progress on all aspects of delivering germplasm services to the nation’s researchers and breeders as planned for this year. Several advances were made to improve the security of the germplasm. These include:
1) replaced failing primary seed cooler and sequestered backup seed samples in a separate fire-proof building, 2) installed low temp failsafe cutout thermostat in tuber cooler, 3) started converting a duplicate set of the clonal tissue culture collection to microtubers, and 4) started adopting true seed Polymerase Chain Reaction - based testing for Potato Spindle Tuber Viroid.
Objective 2. Advances were also made in the characterization and technical use of the germplasm: 1) DNA and phenotype study of populations currently with “unknown” taxonomy, 2) production of a core collection of 62 diploid cultivated potato lines selected for Late blight resistance, 3) demonstration of the novel introgression of Solanum jamesii into cultivated form s of potato, 4) refinement of sample bulking to capture DNA diversity of a population, 5) validation of a backcrossing scheme to convert rare single-genotype accessions in botanical seed form, and 6) conducted genetic structure analysis of primitive cultivated seed populations to inform best method of seedlot propagation.
Accomplishments
1. Collect germplasm at sites in southwest United States with no prior geographic representation with a view to expanding the geographic and genetic diversity of samples kept in the genebank. ARS researchers in Madison, Wisconsin, collected 15 germplasm from the wild in West Texas and southern New Mexico at places not previously known to have natural stands of wild potato and incorporated them into the genebank. These were found at public roadsides, in cooperation with Texas State Parks, and The Nature Conservancy. We assume the geographic rarity of these new stocks is associated with novel, valuable genetics. Thus, new germplasm has been made available to researchers and breeders working on improving the crop. This is similar to stocking a toolbox with an expanded diversity of tools so we have a better chance of fixing problems in the crop, perhaps those not even known yet. These stocks will also be available to study the relationship between plants growing in the wild and those in the genebank, thus helping us understand how complete the genebank collection is with regard to being a genetic resource of potato improvement. For example, germplasm from more collecting sites will allow us to compare basic genetics of a population with the environment of its source location or the distance from other populations of the same species. We already know that these particular species are very rich in useful traits. For example, they have extreme resistance to cold stress, insects, fungi, nematodes, and extreme tuber dormancy.
2. Completed greenhouse botanical seed and clonal multiplication to replenish inventory of samples the genebank can send to researchers and breeders who will create a more profitable crop for farmers. ARS researchers at Madison, Wisconsin, hand-pollinated over 250 families of 20 plants each in a greenhouse for seed increase and performed 19,644 in vitro transfers to maintain fresh propagules of seed and clonal stocks for germplasm requesters, so they will be able to use germplasm to improve the potato crop without delay.
3. Maintained current virus test schedule and records for all seeds and clones so that the genebank can have confidence that samples sent to researchers and breeders do not contain diseases. ARS researchers in Madison, Wisconsin, completed 2,016 tests for Potato Spindle Tuber Viroid and the six common potato viruses. This helped ensure that the more than 10,000 items the U.S. Potato Genebank sent to germplasm users this year did not infect their programs with diseases while they are using those stocks to improve our knowledge base and create breeding stocks that will improve the potato crop, thus improving profit for potato farmers and quality of potatoes purchased and eaten by consumers.
4. Evaluated valuable traits of the potato germplasm in the genebank, such as disease, pest, and stress resistances, as instigated by germplasm users with the ultimate goal of improving the potato crop. ARS researchers in Madison, Wisconsin, assisted specialist researchers in their study of a variety of important potato diseases, pests and stresses. For example, genebank staff and specialist researchers continued cooperative work on making and testing novel populations and propagules for study of Dickeya, an emerging serious tuber rot disease. Genebank staff created unique hybrid families, and the specialist cooperator tested tubers of those families for tuber rot. Another project addressed Zebra Chip, an emerging bacterial disease vectored by an insect that results in reduced yield and tubers with unacceptable mottled chips. In this case, we provided propagules for a progressive screening routine that finally identified individual plants with extreme resistance. In a third cooperative project, we validated an efficient, rapid, lab-based method of testing heat tolerance, a tool that promises to facilitate selecting breeding stocks and new cultivars that can be productive even if grown in regions that become hotter due to climate change. The payoff of all these cooperative projects is expected to be the identification of extreme individuals of the desired state of the traits. Those are very useful for breeding, as well as in studies to identify the physiology and genetics of the trait. Whatever the specific trait needed, the ultimate goal is to give researchers and breeders genetic tools to “build in” to the potato crop. This will maintain the high quality, quantity and economy needed by the U.S. consumer. Scientists who order stocks from the genebank are working on a broad spectrum of topics in potato research and breeding, and as recommended by Crop Germplasm Committee (the committee of experts /National Plant Germplasm System has organized to advise on all aspects of the nation’s germplasm concerns).
Review Publications
Enciso-Maldonado, G.A., Lozoya-Saldana, H., Colinas-Leon, M.T., Cuevas-Sanchez, J.A., Sanabria-Velazquez, A.D., Bamberg, J.B., Raman, K.V. 2022. Assessment of wild Solanum species for resistance to Phytophthora infestans (Mont.) de Bary in the Toluca Valley, Mexico. American Journal of Potato Research. 99:25-39. https://doi.org/10.1007/s12230-021-09856-x.
Bamberg, J.B., Lombard, K. 2022. Cold hardiness variations in Solanum jamesii and Solanum kurtzianum tubers. American Journal of Potato Research. 99:69-72. https://doi.org/10.1007/s12230-022-09862-7.
