QTL Mapping of Yield and Yield Components under Normal and Salt-stress Conditions in Bread Wheat (Triticum aestivum L.)

A population of 186 recombinant inbred lines of bread wheat (Superhead#2/Roshan) was evaluated to identify quantitative trait loci (QTL) for yield and yield components under normal (2 ds m(-1)) and salt-stress (10-12 ds m(-1)) conditions. A genetic map was constructed with 451 markers, including, 23 simple sequences repeats (SSRs) and 428 diversity arrays technology markers (DArTs). The main-effect QTL were identified by composite interval mapping (CIM) analysis using QTL Cartographer v2.5 and Qgene v4.3.2 and a mixed-model-based composite interval mapping (MCIM) method using QTLNetwork v2.1. A total of 98 significant QTL were detected at two testing locations on 20 chromosomes. Of these, only 40 QTL were detected by at least two of these software programs. A total of 24 QTL on ten chromosomes were identified for grain yield, most of which had a minor effect, contributing less than 10 % of the total phenotypic variation. Two grain-yield QTL intervals were detected on 1A(1) and 3B, which contributed 11.02 % and 10.3 % to the total phenotypic variation, respectively. Roshan alleles were associated with an increase in grain yield under stress conditions on 1A(1), 2B(3), 3B, 6B(1), 1D, 2D(1). Among the 20 chromosomes, chromosome 3B with 27 QTL and two distinctive cluster regions was the most important. SSR markers gwm282, gwm247, gwm566, and gwm33 were tightly linked to QTL for the same or different traits under normal, stress or both conditions, and accounted for about 17 %, 43 %, 43 % and 20 % of the total phenotypic variation, respectively. These markers are suitable for marker-assisted selection to improve grain yield under normal and salt-stress conditions.