Project Number: 2050-21000-034-037-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: May 1, 2021
End Date: Apr 30, 2022
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.
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. This project will use the southern oat association mapping panel (SOAP) of 300 oat lines, that was formed in 2015 of mostly elite germplasm (good agronomic performance) from four southern oat breeding programs (UFL, LSU, NCSU and Texas A&M) in addition to germplasm from the National Small Grains Collection (NSGC). Project resources will also provide for characterizing other oat germplasm for stem rust response. 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 Principal Investigator (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. Genome-wide association mapping using GBS-SNPS already obtained for the SOAP will identify molecular markers for further validation and place them in context of both the existing oat consensus linkage map and the anticipated physical genetic map. Markers highly associated with disease resistance will be converted to assay types suitable for high-throughput genotype screening. Crosses will be made for the purposes of validating linked markers and introgressing resistance onto elite germplasm adapted to other U.S. oat production regions. 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.