QTL mapping for salt tolerance associated traits in wheat (Triticum aestivum L.)

Soil salinity is major constraint for wheat production globally and breeding wheat cultivars for salt tolerance by conventional means is difficult. Therefore, understanding molecular components associated with salt tolerance is needed to facilitate breeding for salt tolerance in wheat. In this investigation, quantitative trait loci (QTL/s) associated with salt tolerance were identified using recombinant inbred lines (RILs) developed from a cross between Kharchia 65 (KH 65) and HD 2009 cultivars. Parents and RILs were evaluated under controlled and sodic stress conditions for 11 morpho-physiological and yield determining traits for two consecutive crop cycles. Simple sequence repeat (SSR) markers were employed for mapping studies. Using composite interval mapping approach, 11 QTLs on 6 chromosomal regions (1B, 2D, 5D, 6A, 6B and 7D) for 7 different traits were identified explaining proportion of the phenotypic variance (PVEs) (2.5-12.8%) under control condition. Three of the QTLs (QCph.iiwbr-2D.1, QCle.iiwbr-6A and QCle.iiwbr-6B) were most consistent in all the environments and explained PVEs (5.1-12.8%) under control condition. Twenty-five QTLs were detected on 7 chromosomal regions (1A, 1B, 2D, 4D, 5D, 6A and 7D) for 10 different traits explaining PVEs (2.6-15.1%) under salt stress. Six of the QTLs namely QSNa(+).iiwbr-1B, QSK(+).iiwbr-2D, QStn.iiwbr-4D, QSph.iiwbr-2D.1, QSph.iiwbr-6A and QSdth.iiwbr-2D were consistently reproducible in all the environments and explained PVEs ranging from 2.6 to 15.1%. SSR markers namely gwm 261, wmc 112, and cfd 84 were tightly linked with QTLs for K+ content; DTH and DTA; and TN and NE, respectively. Several QTLs contributing towards salt tolerance were present on 2D chromosome. Most of the QTLs linked with salt tolerant traits were inherited from KH 65 signifying the presence of several genes associated with salt tolerance in this cultivar. The information is very useful in marker assisted breeding to enhance salt tolerance in wheat.