Identification, introgression, and molecular marker genetic analysis and selection of a highly effective novel oat crown rust resistance from diploid oat, Avena strigosa

Authors: Rines, Howard; MILLER, MARISA - University Of Minnesota; Carson, Martin; Chao, Shiaoman; TIEDE, TYLER - University Of Minnesota; WIERSMA, JOCHUM - University Of Minnesota; Kianian, Shahryar

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2017
Publication Date: 12/6/2017
Citation: Rines, H.W., Miller, M.E., Carson, M.L., Chao, S., Tiede, T., Wiersma, J., Kianian, S. 2017. Identification, introgression, and molecular marker genetic analysis and selection of a highly effective novel oat crown rust resistance from diploid oat, Avena strigosa. Theoretical and Applied Genetics. 131(3):721-733. http://doi.org/10.1007/s00122-017-3031-0.
DOI: https://doi.org/10.1007/s00122-017-3031-0

Interpretive Summary: A new highly effective resistance to oat crown rust (Puccinia coronata f. sp. avenae) was identified in the diploid wild oat, Avena strigosa, and introgressed into hexaploid cultivated oat. We describe here the, discovery, introgression, mapping and identification of tightly linked molecular markers and transfer of this novel adult plant oat crown rust resistance gene into adapted cultivars. This gene confers broad resistance (i.e., field resistance to a wide diversity of the pathogen population) to this devastating disease of oat making it highly valuable to scientists across the globe. Additionally, the details of this process will be of value to other plant science researchers interested in developing more durable resistant cultivars.

Technical Abstract: A new highly effective resistance to oat crown rust (Puccinia coronata f. sp. avenae) was identified in the diploid oat Avena strigosa PI 258731 and introgressed into hexaploid cultivated oat. Young plants with this resistance show moderate susceptibility, whereas older plant tissues and adult plants are resistant with no virulent isolates encountered in over eight years of testing. Resistance was incorporated into hexaploid oat by embryo rescue, colchicine chromosome doubling followed by backcrosses with a hexaploid parent, and selection for stable transmission of resistance. To mitigate flag leaf and panicle chlorosis/necrosis associated with the resistance, crosses were made with derived resistant lines to breeding lines of divergent parentage followed by selection. Subsequently, two F2 sister lines, termed MNBT1020-1 and MNBT1021-1, were identified in which the chlorosis/necrosis was reduced. These two lines performed well in replicated multi-location state trials in 2015 and 2016 out-yielding all cultivar entries. Segregating F2:3 plants resulting from crosses of MNBT lines to susceptible parents were genotyped with the oat 6K SNP array, and SNP loci with close linkage to the resistance were identified. KASP assays generated from linked SNPs showed accurate discrimination of the resistance in derivatives of the resistant MNBT lines crossed to susceptible breeding lines. A TaqMan marker was developed and correctly identified homozygous resistance in over 95% of 379 F4 plants when rust was scored in F4:5 plants in the field. Thus, a novel highly effective resistance and associated molecular markers are available for use in breeding, genetic analysis, and functional studies.