Mapping quantitative trait loci associated with grain filling duration and grain number under terminal heat stress in bread wheat (Triticum aestivumL.)

Abstract

Terminal heat stress has the potential negative impact on wheat production across the world, especially in South Asia. Under the threat of terminal heat stress, wheat genotypes with stay green trait would suffer from high temperature stress during their long grain filling duration (GFD). The genotypes with short GFD would be advantageous. To identify quantitative trait loci (QTL) for heat tolerance, a RIL population of K 7903 (heat tolerant) and RAJ 4014 (heat sensitive) wheat genotypes was investigated under timely and late‐sown conditions. Heat susceptibility index of GFD, yield components and traits under late‐sown condition were used as phenotypic data for QTL identification. Stable QTLs associated with these traits were identified on chromosomes 1B, 2B, 3B, 5A and 6B. The LOD value ranged from 2.9 to 5.0 and the corresponding phenotyping variation explained ranged from 12.0–22%. QTL for heat susceptibility index for the grain filling duration were colocalized with QTL for productive tillers under late sown and GFD under late‐sown condition on chromosomes 1B and 5A, respectively. These genomic regions could be exploited for molecular wheat breeding programmes targeting heat tolerance.

Analysis of contributors to grain yield in wheat at the individual quantitative trait locus level

“…(), Sherman, Martin, Blake, Lanning, and Talbert () and Sharma et al. (). The QTLs for TN were detected on 1B, 5A and 6A in ITMI previously, and they can be reproducibly identified in the present study (Chesnokov et al., ; Kumar et al., ; Li et al., ).…”

Genotype–Phenotype Relationships for High‐Temperature Tolerance: An Integrated Method for Minimizing Phenotyping Constraints in Wheat

“…Furthermore, temperature and moisture gradients between or among the plots were effectively avoided by means of a hot water radiator‐type heating system and a highly controlled drip irrigation system. Other features that led to improved phenotyping under heat stress included ensuring a uniform plant population through use of a specially designed dibbler (Sharma et al, 2016) and staggered planting to synchronize plant phenology (Pandey et al, 2014; Sharma et al, 2016). Sharma (2015) reported that the desired seed depth and plant spacing could be maintained with greater precision by the dibbling method than by conventional methods such as seed drills or hand sowing.…”

“…Seventy‐three recombinant inbred lines (RILs) were developed through single‐seed descent from a cross between two parental spring wheat genotypes, ‘RAJ4014’ and ‘WH730’. RAJ4014 does not perform well under late‐sown (LS, terminal heat stress) conditions (Pandey et al, 2014; Sharma et al, 2016, 2018), but WH730 is adapted to LS conditions (Rane and Nagarajan, 2004; Pandey et al, 2014; Sharma et al, 2015, 2018). This genotype has been shown to have superior heat tolerance on the basis of its ability to stay green under heat stress (Pandey et al, 2014; Sharma et al, 2018).…”

“…The RWC and EC were measured in the flag leaves in three biological replicates (Barrs and Weatherley, 1962; Murray et al, 1989). For the pollen viability test, fresh wheat pollen grains were trapped on egg albumin‐coated glass slides (Sharma et al, 2016) and stained with an aniline blue lacto‐phenol solution (Kearns and Inouye, 1993).…”

“…W heat ( Triticum aestivum L.) is the major staple food crop for many countries and is grown in a diverse range of agroecological environments. Biotic and abiotic factors under changing climate conditions may be major constraints for future wheat production (Joshi et al, 2007; Sharma et al, 2016). Among the abiotic factors limiting wheat production, continuous or periodic heat stress has emerged as a major threat, particularly in subtropical environments (Reynolds et al, 2016).…”