Identification of QTLs Associated with Agronomic and Physiological Traits under Salinity Stress in Barley

Salinity tolerance is a genetically and physiologically complex trait, controlled by Quantitative Trait Loci (QTLs). In order to map the QTLs associated with agronomic and physiological traits, ۱۴۹ doubled haploid lines derived from a cross between Clipper (salt susceptible) and Sahara ۳۷۷۱ (salt tolerant) barley genotypes were evaluated under natural saline-stress and non-stress conditions using ۱۴ traits. QTL analysis was performed based on the composite interval mapping method, using the genetic linkage map consisting of ۵۱۷ molecular markers which spanned a total of ۱۵۰۲.۴ cM. A total of ۷۸ QTLs for days to heading, relative water content, chlorophyll content, plant height, spike length, days to maturity, biomass, grain yield, harvest index, grain number per spike, ۱,۰۰۰-kernel weight, Na+, K+ concentrations and K+/Na+ ratio, were determined, with ۴۰ and ۳۸ QTLs under normal and salinity environments, respectively. Most of the detected QTLs were located on chromosome ۲H. The phenotypic variation explained by individual QTLs ranged from ۳.۳ to ۶۸.۶%. A major QTL was identified at both saline-stress and non-stress conditions in the vicinity of Vrs۱ on chromosome ۲H, related to biomass, grain number per spike, ۱,۰۰۰ kernel weight, plant height and grain yield. This QTL may be useful in the barley breeding programs for improving salt tolerance by marker-assisted selection. Furthermore, some stable QTLs, were identified for days to heading, biomass, spike length, grain number per spike, ۱,۰۰۰ kernel weight, and K+ content which can be regarded as promising QTLs for breeding purposes.