Association mapping of drought stress response for yield and quality traits in barley

Abstract

Barley (Hordeum vulgare L.) is a major cereal crop grown worldwide for human consumption, malting, and animal feed. Drought is one of the major abiotic stresses that reduce grain yield and quality in barley. This study was conducted to evaluate a set of 250 barley lines grown under irrigated, water-stressed, and rainfed conditions and to identify genomic regions associated with 10 traits related to grain yield and quality across eight independent field environments. Variability was observed among barley lines for tolerance to water-stressed conditions in all tested environments. Genotype and environment both contributed to the phenotypic variation of the barley lines. Population structure analysis identified two subpopulations using 20,700 single nucleotide polymorphism (SNP) markers. Genome-wide association mapping detected 74 significant SNPs (p ≤ 6.5 × 10⁻⁶), representing 14 quantitative trait loci (QTLs), on all barley chromosomes, except 3H. The QTL, QBG.ARS.7H, associated with beta-glucan (BG), was consistently detected across environments and explained 13.93% of phenotypic variation. Carriers of the minor allele for the BG-associated SNP, JHI-Hv50k-2016-488035, exhibited up to 14.65% higher BG content, on average, compared with carriers of the common allele. This study advances our understanding of the genetics of barley response to water-stress conditions and suggests molecular markers for QTL, which may be used in barley improvement.