Genetic analysis and quantitative trait locus mapping of PEG-induced osmotic stress tolerance in cotton

Water stress is one of the major abiotic stresses that adversely affect cotton production. Seedlings of 142 backcross inbred lines (BILs) derived from Pima cotton Pima S-7' (Gossypium barbadense L.)xUpland cotton Sure-Grow 747'(G.hirsutum L.) were evaluated in two tests for plant height, fresh shoot weight and root weight under two treatments (5% PEG and water-control conditions) using a hydroponic system in the greenhouse. The experiment in each test was a randomized complete block design with three replicates. The analysis of variance for the two tests detected significant genotypic variation in PEG-induced stress tolerance within the BIL population and between the parents. Heritabilities were moderate to high and were higher under the control conditions than under the PEG treatment, and the three traits were also significantly and positively correlated. Based on a linkage map with 292 loci, six QTLs were detected including two for plant height, and two each for fresh shoot weight and root weight. This study represents the first report in using a permanent mapping population in genetic and linkage analysis of water stress tolerance in cotton.