QTL mapping of terminal heat tolerance in hexaploid wheat (T. aestivum L.)

Abstract

High temperature (>30 °C) at the time of grain filling is one of the major causes of yield reduction in wheat in many parts of the world, especially in tropical countries. To identify quantitative trait loci (QTL) for heat tolerance under terminal heat stress, a set of 148 recombinant inbred lines was developed by crossing a heat-tolerant hexaploid wheat (Triticum aestivum L.) cultivar (NW1014) and a heat-susceptible (HUW468) cultivar. The F(5), F(6), and F(7) generations were evaluated in two different sowing dates under field conditions for 2 years. Using the trait values from controlled and stressed trials, four different traits (1) heat susceptibility index (HSI) of thousand grain weight (HSITGW); (2) HSI of grain fill duration (HSIGFD); (3) HSI of grain yield (HSIYLD); and (4) canopy temperature depression (CTD) were used to determine heat tolerance. Days to maturity was also investigated. A linkage map comprising 160 simple sequence repeat markers was prepared covering the whole genome of wheat. Using composite interval mapping, significant genomic regions on 2B, 7B and 7D were found to be associated with heat tolerance. Of these, two (2B and 7B) were co-localized QTL and explained more than 15 % phenotypic variation for HSITGW, HSIGFD and CTD. In pooled analysis over three trials, QTL explained phenotypic variation ranging from 9.78 to 20.34 %. No QTL × trial interaction was detected for the identified QTL. The three major QTL obtained can be used in marker-assisted selection for heat stress in wheat.

Heat Tolerance in Wheat - A Key Strategy to Combat Climate Change through Molecular Markers

“…It is therefore recommended to design a breedingled approach to adapting wheat to elevated temperature environments (Reynolds et al, 2007;. The genetic basis of high temperature tolerance in wheat is not very well understood; to date it has been assessed largely by monitoring the response of grain yield (Yang et al, 2002;Pinto et al, 2010), grain filling duration (Yang et al, 2002), grain size, canopy temperature depression (Reynolds et al, 1994;Ayeneh et al, 2002), a heat sensitivity index (Mohammadi et al, 2008;Mason et al, 2010;Paliwal et al, 2012) or various senescence-related traits (Vijayalakshmi et al, 2010) to exposure to high temperature.…”

“…In contrast, photosystem II (PSII), particularly the oxygen-evolving complex, is deactivated even at slightly elevated temperatures (Yamane et al, 1998), demonstrating that this process is especially sensitive to temperature stress (Pushpalatha et al, 2008). Table.3 QTLs for heat stress tolerance in NW1014 (heat tolerant) × HUW468 (heat susceptible) RILs population (Paliwal et al, 2012) …”

Climate Change: Seed Production and Options for Adaptation

“…This would provide a system-wide phenome to genome analysis [123] allowing accurate trait mapping, introgression of superior alleles, or cloning of major quantitative trait loci (QLTs). Genome-wide analyses have started to provide some candidate genes involved in thermotolerance [135][136][137][138]. Understanding the genetic basis of heat tolerance is essential to allow breeders to facilitate the transfer of genes for heat tolerance to commercial cultivars [123,134].…”

Germplasm evaluation of heat tolerance in bread wheat in Tel Hadya, Syria

“…Therefore, breeding for heat tolerance in wheat is a major global concern (Paliwal et al, 2012). Consequently, development of heat-tolerant cultivars is of importance in wheat breeding programs (Sikder and Paul, 2010;Mohamed, 2013).…”