Mapping quantitative trait loci for drought tolerance/susceptibility indices and estimation of breeding values of doubled haploid lines in wheat (

Abstract

Water shortage and drought stress in the reproductive stage of wheat (Triticum aestivum L.) considerably affect grain yield (GY). Mapping genes for drought tolerance assists in selection for drought improvement. In the present study, we evaluated breeding values based on best linear unbiased predictions (BLUPs) and drought tolerance/susceptibility indices (DT/SIs), and identified marker–phenotype associations in 220 doubled haploid (DH) lines. The DH lines were evaluated for GY and 1000-grain weight (TGW) under drought stress and well-watered conditions at the heading stage in 2015 and 2016. The linkage map comprised 1333 SSR, DArT and SNP markers with an average density of 2.18 markers per cM. The BLUPs were significantly correlated with GY of the lines. Significant correlations were found between stress tolerance score (STS) and drought response index, yield index, yield stability index, geometric mean productivity and stress tolerance index. The lines DH_R295 and DH_R360 had the highest breeding values for GY and STS. Major QTLs, one main effect and eight epistatic, were identified for the DT/SIs. A major QTL was identified for STS-GY, which explained 11.39% of the STS-GY variation in 2015. This QTL was co-located with QTLs for yield index-GY and yield stability index-GY within the BS00066932_51–gwm0314b marker interval (48 cM on 3B). The search for gene annotation showed that BS00066932_51 overlapped with protein-encoding genes. In conclusion, the QTL-linked markers help genotype selection for the improvement of drought tolerance, and they are good candidates for use in genomic selection.