Genome Wide Association Mapping of Seedling and Adult Plant Resistance to Barley Stripe Rust in India

Abstract

Performing genome-wide association mapping (GWAM), we identified and estimated effects of loci underlying quantitative resistance to barley stripe rust, caused by Puccinia striiformis f.sp. hordei (Psh). Barley stripe rust occur worldwide and is a major disease in South Asia. The 261 barley genotypes of the Hi-AM panel consisting of germplasm from North and South America, Europe, Australia and from ICARDA barley breeding program were screened for Psh resistance at seedling and adult plant stages. Seedling resistance was evaluated with the five prevalent Psh races in India. Screening for the adult plant stage resistance was also performed in two different locations by inoculating with a mixture of the five races used for seedling screening. Results of GWAM showed a total of 45 QTL located across the seven barley chromosomes for seedling resistance to the five races and 18 QTL for adult plant stage resistance. Common QTL for different races at seedling stage were found on all chromosomes except on chromosome 1H. Four common QTL associated with seedling and adult plant stage resistance were found on chromosomes 2H, 5H, and 6H. Moreover, one of the QTL located on the long arm of chromosome 5H showed stable effects across environments for adult plant stage resistance. Several QTL identified in this study were also reported before in bi-parental and association mapping populations studies validating current GWAM. However 15 new QTL were found at adult plant stage on all chromosomes except the 4H, explaining up to 36.79% of the variance. The promising QTL detected at both stages, once validated, can be used for MAS in Psh resistance breeding program globally.