Location: Small Grains and Potato Germplasm Research
Project Number: 2050-21000-038-008-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: May 1, 2021
End Date: Apr 30, 2024
Objective:
This project will decipher the genetic architecture of un-tapped stem rust (Puccinia graminis Pers. f.sp. avenae) resistance in Southern U.S. oat germplasm by placing genetic map locations of resistance alleles in the context of molecular markers suitable for high-throughput genotyping. The developed knowledge and molecular tools will be used in crossing to develop germplasm carrying stem rust resistance alleles for oat breeding programs.
Approach:
This project extension will evaluate the southern oat association mapping panel (SOAP), and other oat germplasm for reaction to stem rust in the field and under controlled environmental conditions. The data from the 2022-2023 growing season will be combined with that from the previous season to provide robust data for genome-wide association mapping. Stem rust (caused by Puccinia graminis Pers. f.sp. avenae) is a major oat disease globally, including in the southern US, and causes considerable damage to yield and grain quality. Over the past decade, the southern oat breeding programs (UFL, LSU, NCSU and Texas A&M) have developed winter and facultative oat germplasm tolerant or resistant to stem rust. However, the genes conditioning these disease reactions have not been mapped and their underlying mechanisms of action are not understood. The oat germplasm developed by the southern US oat breeding programs is relatively genetically distinct, with many unique traits. Thus, it is likely that at least some of the disease resistance in this germplasm has not yet been deployed in oat cultivars developed for other production regions. This un-tapped genetic variation within southern oat germplasm has the potential to provide oat cultivars with new genetic resistance to stem rust. Stem rust disease response will be scored by the Cooperators under field conditions at Citra and Quincy, Florida (oat rust disease hotspots), Baton Rouge, Louisiana and by the ARS PI under controlled conditions at Aberdeen, Idaho. Stem rust differentials will be planted to identify virulence combinations present in each environment and isolates will be sent to the USDA Cereal Disease Lab for characterization. Markers highly associated with disease resistance will be converted to assay types suitable for high-throughput genotype screening. Characterization and mapping of stem rust resistance identified in the SOAP and other developed RILS will ensure that the resistance deployed into subsequently released germplasm is both novel and effective.
