Genome-wide association study of resistance to PstS2 and Warrior races of Puccinia striiformis f. sp. tritici (stripe rust) in bread wheat landraces

Stripe or yellow rust, caused by Puccinia striiformis Westend. f. sp. tritici is a
major threat to bread wheat production worldwide. The breakdown in resistance
of certain major genes and newly emerging aggressive races of stripe rusts
pose serious concerns in all main wheat growing areas of the world. To identify
new sources of resistance and associated QTL for effective utilization in
future breeding programs an association mapping (AM) panel comprising of
600 bread wheat landraces collected from eight different countries conserved
at ICARDA gene bank were evaluated for seedling and adult plant resistance
against the PstS2 and Warrior races of stripe rust at the Regional Cereal Rust
Research Center (RCRRC), Izmir, Turkey during 2016, 2018 and 2019. A set of
25,169 informative SNP markers covering the whole genome were used to examine
the population structure, linkage disequilibrium and marker-trait associations
in the AM panel. The genome-wide association study (GWAS) was carried
out using a Mixed LinearModel (MLM).We identified 47 SNP markers across 19
chromosomes with significant SNP-trait associations for both seedling stage and adult plant resistance. The threshold of significance for all SNP-trait associations
was determined by the false discovery rate (q)≤0.05. Three genomic regions
(QYr.1D_APR, QYr.3A_seedling and QYr.7D_seedling) identified in this study do
not correspond to previously reported Yr genes or QTL, suggesting new genomic
regions for stripe rust resistance.