Mapping QTL for agronomic and root traits in the Kukri/RAC875 wheat (Triticum aestivum L.) population under drought stress conditions

Abstract

Drought is one of the most important abiotic stresses affecting wheat growth. Evaluation of a structured population over seasons and moisture conditions allow for the detection of genes involved in drought tolerance. The aims of the present study were to analyze root and agronomic characters under two moisture conditions and identify marker-trait associations in 220 doubled haploid (DH) lines developed from a cross between Kukri and RAC875. The DH lines were evaluated for grain yield (GY) and several root and agronomic traits in four trials included drought stress experiments (DrExp) at heading stage and well-watered conditions (NExp) throughout the growth season in 2015 and 2016. A linkage map comprised of 1333 SSR, DArT and SNP markers were used for the analysis of quantitative traits loci (QTL). The results of QTL analysis showed that four and seven QTL were identified for root traits in the DrExp 15 and DrExp 16 trials, respectively. The results of QTL analysis suggested that the contribution of the three genomes to drought tolerance was not similar. The Q.Rdrw-4A QTL explained 7.05 and 10.43% of root dry weight variances in the DrExp15 and DrExp 16 trials, respectively. A QTL mapped on the D_GA8KES401CIKOJ–160-BS00067285_51 marker interval for root length was co-localized with a QTL for grain weight per spike under drought conditions. A year-specific main effect QTL and several stable epistatic QTL were identified for days to heading in the DrExp and NExp experiments, respectively. Search for gene annotation in the wheat genome showed that the position of this QTL was overlapped with the tRNA, sRNA and protein-encoding genes. Three QTL were identified for GY of which the Q.Gy-2D QTL identified in NExp 16 whilst Q.Gy-3D and an epistatic effect detected in drought conditions. The common QTL identified allows for increasing selection efficiency and the fine-tuning of root and agronomic traits for sustainable wheat production under water deficit conditions.