Genome-wide association studies revealed novel stripe rust resistance QTL in barley at seedling and adult-plant stages

Barley stripe rust, Puccinia striiformis f. sp. hordei, (PSH) occurs worldwide and is one of the major barley diseases of South Asia and North Africa. The aim of this study was to identify and map rust resistance loci at the seedling and the adult plant stages in 336 barley genotypes assembled at ICARDA as AM-2014. The seedling resistance to PSH was evaluated in the greenhouse individually for six virulent races originated from India. The adult stage resistance to PSH was evaluated in field located at Durgapura, Rajasthan, India. The AM-2014 panel was genotyped with infinium iSelect 9K barley SNP markers and genome-wide association studies were carried out using mixed linear model accounting for population structure (PCA) and kinship (K) as covariates. Eleven barley genotypes were identified resistant to all six PSH races at the seedling stage while these genotypes were also resistant at adult plant stage in the field. The most effective SNP markers (at least one for each QTL) associated with rust resistance was also identified using stepwise regression. A total of 17 and 25 resistance QTL to six races of PSH were identified in two- and six-rowed barley at the seedling stage, respectively. While, six and seven resistance QTL to PSH were detected at the adult stage in two- and six-rowed barley, respectively. The novel PSH resistant QTL detected at the seedling and adult stages are important for barley breeding programs globally.