A QTL hot spot region on chromosome 1B for nine important traits under terminal drought stress conditions in wheat

Abstract

Drought tolerance is a polygenic trait and is considered as one of the most important limiting factors to productivity of wheat and other crops around the world. Identifying drought-responsive genes using quantitative trait loci (QTL) and association analysis is one of the ways of developing drought tolerance cultivars. In order to detect QTLs for terminal drought tolerance in wheat, QTL analyses were conducted using an F12 recombinant inbred line population. A total of 53 main effects QTLs on 15 different chromosomes and 12 QTL by QTL (QQ) interactions on 13 different chromosomes were detected for yield, yield components and some agronomic traits using composite interval mapping and mixed-model based composite interval mapping analysis. The most significant QTL for grain yield was QYld.1A1 on 1A1, explaining 19.7% of the phenotypic variance under terminal drought stress. In addition, a QTL hot-spot region including important QTLs for grain yield, biological yield, grain number per spike, thousand grain weight, spike length, spike weight, stem weight and plant height was identified in the same region on chromosome 1B and clustered within the marker interval between wpt-3465 and wpt-2019. The DArT marker Wpt-5801 at the position of 67.7 cM showed linkage with all traits using single marker regression analysis. The BLAST search of markers sequences on the wheat genome identified 390 gene stable identifiers. Gene ontology analysis showed that the most dominant terms were ‘binding’ and ‘single-organism catabolic process’ for molecular function and biological process categories, respectively. This QTL hot-spot region with nine important QTLs could be used to improve drought tolerance after validation.