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, 149 doubled haploid lines derived from a cross between Clipper (salt susceptible) and Sahara 3771 (salt tolerant) barley genotypes were evaluated under natural saline-stress and non-stress conditions using 14 traits. QTL analysis was performed based on the composite interval mapping method, using the genetic linkage map consisting of 517 molecular markers which spanned a total of 1502.4 cM. A total of 78 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, 1,000-kernel weight, Na+, K+ concentrations and K +/Na+ ratio, were determined, with 40 and 38 QTLs under normal and salinity environments, respectively. Most of the detected QTLs were located on chromosome 2H. The phenotypic variation explained by individual QTLs ranged from 3.3 to 68.6%. A major QTL was identified at both saline-stress and non-stress conditions in the vicinity of Vrs1 on chromosome 2H, related to biomass, grain number per spike, 1,000 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, 1,000 kernel weight, and K+ content which can be regarded as promising QTLs for breeding purposes.