Location: Small Grains and Potato Germplasm Research
Project Number: 2050-21000-038-027-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2025
End Date: Oct 31, 2026
Objective:
Southern US oat germplasm carries largely uncharacterized resistance to stem rust disease (Puccinia graminis Pers. f.sp. avenae). This project will use phenotype and genotype data already in-place to identify the genomic locations of genes conferring resistance to stem rust disease. Molecular markers suitable for high-throughput genotyping of oat breeding material will be developed.
Approach:
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. An association mapping panel, called the southern oat association mapping panel (SOAP), has been genotyped using genotype-by-sequencing methods. These 300 elite oat lines, have already been evaluated for reaction to natural stem rust infection over three growing seasons at three locations. Genome-wide association methods will be used to 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. Project resources will provide for characterizing other oat germplasm for stem rust response for validation of mapped resistance. 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. 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. 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.