Association mapping of resistance to stripe rust in a globally diverse panel of wheat accessions
Effective control of stripe rust (YR) requires deployment of resistant cultivars. Adult plant resistance (APR) is preferred over all-stage resistance because of its putatively durable nature. Discovery of new sources of resistance is a priority to combat rapidly evolving Pst races. Genebanks contain untapped genetic diversity that likely harbor novel resistance genes. We examined a diverse panel of 300 lines sourced from the Vavilov Institute, including landraces, cultivars and breeding lines from 28 countries. The most virulent Pst pathotype in Australia (134 E16 A+,Yr17+,Yr27) was used for all experiments, where YR reactions were determined on seedlings in a greenhouse and on adult plants in a field disease nursery. A total of 54% of accessions displayed all-stage resistance and 33% displayed moderate to high levels of APR. Accessions were genotyped using the DArTseq genotyping platform and using an association mapping approach we identified genomic regions associated with YR resistance. These were aligned with previously reported QTL and cataloged resistance genes on a consensus map. This enabled identification of novel genomic regions. Accessions carrying high levels of APR were screened using markers linked to well-known APR genes (i.e. Yr18, Yr29 and Yr46). Twenty two accessions carrying potentially novel sources of APR to YR were identified. Our current efforts are aimed at further characterizing and validating these genetic resources against a wide array of pathotypes and environments around Australia.