Genome Wide Association Mapping for Stripe Rust Resistance in Domesticated Emmer Wheat (Triticum turgidum ssp. dicoccum).

Abstract

Wheat (Triticum aestivum L.) is one of the major crops and a staple food for about 35% of the world population. Wheat production is constantly threatened by the stripe rust, one of the devastating wheat diseases and caused by Puccinia striiformis f. sp. tritici (Pst). Improving the disease resistance of wheat cultivars is the most efficient and sustainable way to control stripe rust. In this study, we aimed to explore the novel resistance resources in a collection of 180 cultivated emmer wheat accessions (T. turgidum ssp. dicoccum) collected from 32 countries on five continents. The cultivated emmer wheat accessions were genotyped by wheat Illumina® iSelect 9 K SNP array and phenotypes were evaluated in greenhouse using four races and in five field environments. Conducting genome wide association study (GWAS), we identified 14 QTLs associated with stripe rust resistance. Two QTLs, QYr.emmer-4A.2 and QYr.emmer-6A confer all stage resistance (ASR) and 12 QTLs, located on chromosome 1A, 2A, 2B, 3A, 3B, 4A, 5A, 5B, 7A and 7B, confer adult plant resistance (APR) to stripe rust. Compared with the known stripe rust resistance QTLs, most of the QTLs identified in this study are very likely novel QTLs. The APR QTL, QYr.emmer-7A, was consistently detected among multiple data sets from different environments and was validated using a bi-parental mapping population. The SNPs, SSR markers and the genomic loci identified in this study will provide very useful information for QTLs mapping and resistance breeding programs.