Genome Wide Association Study of Resistance to PstS2 and Warrior Races of Stripe (Yellow) Rust in Bread Wheat Landraces.

Abstract

Stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici is a major threat to wheat production worldwide. The breakdown in resistance of certain major genes and new emerging aggressive races of stripe rusts are causing serious concerns in all main wheat growing areas of the world. To search for new sources of resistance genes and associated QTL for effective utilization in future breeding programs an association mapping 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 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 association mapping panel. The genome-wide association study (GWAS) was carried out using a Mixed Linear Model (MLM). We identified 47 SNP markers at 19 genomic regions with significant SNP-trait associations for both seedling and adult plant stage 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 are far away from any previously reported Yr gene or QTL hence, tagging novel genomic regions. The In-silico analysis of the novel QTL regions identified candidate resistance genes encoding proteins putative to plants disease resistance and defense mechanism.