Mapping QTLs related to boron uptake and accumulation in shoots of barley at seedling and maturity stages using microsatellite markers

Boron is an essential micronutrient for plant growth and development and its role in cell wall, maintenance of plasma membrane function and several metabolite pathways is well documented. In this experiment, 150 barley doubled haploid lines derived from the cross between Clipper and Sahara3771 varieties were evaluated to identify genomic regions involved in boron uptake efficiency. The studied traits were boron concentration and content as well as dry weight per plant at seedling and maturity stages under greenhouse conditions. Linkage analysis was performed using 125 polymorphic SSR markers based on minimum LOD of 3 and maximum distance of 50 cM between two adjacent markers. The resulted linkage map spanned 1521.8 cM of barley genome with 14.09 cM distance between two markers. Based on composite interval mapping, 23 QTLs were identified for the traits under study. For dry weight per plant, one and three, boron concentration, six and five and boron content per plant, four and four QTLs were identified at seedling and maturity stages, respectively. The detected QTLs for dry weight per plant, boron concentration and content determined about 28, 61 and 40% of total phenotypic variation of the traits at seedling stage and 34, 51 and 36% at maturity stage, respectively. Transgressive segregation was observed for all traits indicating the presence of desirable parental allele combinations in the progenies. Negative and positive additive effects for identified QTLs showed the inheritance of favorable alleles from both parental lines to progenies in the detected loci. For the studied traits, four QTLs were common that could be due to genetic linkage or plieotropic effects. The markers showed tight linkage with major QTLs, could be used in marker assisted selection breeding programs for selection of superior lines and incorporating of favorable alleles into commercial barley varieties.