Identification of QTL for reducing loss of grain yield under salt stress conditions in bi-parental populations derived from wheat landrace Hongmangmai.

A novel QTL (QSt.nftec-2BL) was mapped to a 0.7 cM interval on chromosome 2B. Plants carrying QSt.nftec-2BL produced higher grain yields by up to 21.4% than otherwise in salinized fields. Wheat yield has been limited by soil salinity in many wheat-growing areas globally. The wheat landrace Hongmangmai (HMM) possesses salt tolerance as it produced higher grain yields than other tested wheat varieties including Early Premium (EP) under salt stresses. To detect QTL underlying this tolerance, wheat cross EP × HMM was chosen to serve as mapping population that was homozygous at Ppd (photoperiod response gene), Rht (reduced plant height gene) and Vrn (vernalization gene); thus, interference with QTL detection by these loci could be minimized. QTL mapping was conducted firstly using 102 recombinant inbred lines (RILs) that were selected from the EP × HMM population (827 RILs) for similarity in grain yield under non-saline condition. Under salt stresses, however, the 102 RILs varied significantly in grain yield. These RILs were genotyped using a 90 K SNP (single nucleotide polymorphism) array; consequently, a QTL (QSt.nftec-2BL) was detected on chromosome 2B. Then, using 827 RILs and new simple sequence repeat (SSR) markers developed according to the reference sequence IWGSC RefSeq v1.0, location of QSt.nftec-2BL was refined to a 0.7 cM (6.9 Mb) interval flanked by SSR markers 2B-557.23 and 2B-564.09. Selection for QSt.nftec-2BL was performed based on the flanking markers using two bi-parental wheat populations. Trials for validating effectiveness of the selection were conducted in salinized fields in two geographical areas and two crop seasons, demonstrating that wheat plants with the salt-tolerant allele in homozygous status at QSt.nftec-2BL produced higher grain yields by up to 21.4% than otherwise.