Mapping QTLs for grain yield components in wheat under heat stress

Abstract

The current perspective of increasing global temperature makes heat stress as a major threat to wheat production worldwide. In order to identify quantitative trait loci (QTLs) associated with heat tolerance, 251 recombinant inbred lines (RILs) derived from a cross between HD2808 (heat tolerant) and HUW510 (heat susceptible) were evaluated under timely sown (normal) and late sown (heat stress) conditions for two consecutive crop seasons; 2013–14 and 2014–15. Grain yield (GY) and its components namely, grain weight/spike (GWS), grain number/spike (GNS), thousand grain weight (TGW), grain filling rate (GFR) and grain filling duration (GFD) were recorded for both conditions and years. The data collected for both timely and late sown conditions and heat susceptibility index (HSI) of these traits were used as phenotypic data for QTL identification. The frequency distribution of HSI for all the studied traits was continuous during both the years and also included transgressive segregants. Composite interval mapping identified total 24 QTLs viz., 9 (timely sown traits), 6 (late sown traits) and 9 (HSI of traits) mapped on linkage groups 2A, 2B, and 6D during both the crop seasons 2013–14 and 2014–15. The QTLs were detected for GWS (6), GNS (6), GFR (4), TGW (3), GY (3) and GFD (2). The LOD score of identified QTLs varied from 3.03 (Qtgns.iiwbr-6D) to 21.01 (Qhsitgw.iiwbr-2A) during 2014–15, explaining 11.2 and 30.6% phenotypic variance, respectively. Maximum no of QTLs were detected in chromosome 2A followed by 6D and 2B. All the QTL detected under late sown and HSI traits were identified on chromosome 2A except for QTLs associated with GFD. Fifteen out of 17 QTL detected on chromosome 2A were clustered within the marker interval between gwm448 and wmc296 and showed tight linkage with gwm122 and these were localized in 49–52 cM region of Somers consensus map of chromosome 2A i.e. within 18–59.56 cM region of chromosome 2A where no QTL related to heat stress were reported earlier. Besides, three consistent QTLs, Qgws.iiwbr-2A, Qgns.iiwbr-2A and Qgns.iiwbr-2A were also detected in all the environments in this region. The nearest QTL detected in earlier studies, QFv/Fm.cgb-2A was approximately 6cM below the presently identified QTLs region, respectively Additionally, QTLs for physiological and phenological traits and plant height under late sown and HSI of these traits were also detected on chromosome 2A. QTL for HSI of plant height and physiological maturity were located in the same genomic region of chromosome 2Awhereas QTLs for physiological and phonological traits under late sown were located 8cM and 33.5 cM below the genomic location associated with grain traits, respectively in consensus map of Somers. This QTL hot-spot region with consistent QTLs could be used to improve heat tolerance after validation.

Genome-Wide Association Mapping of Seedling Heat Tolerance in Winter Wheat

“…We believe that these are the true chromosomes that harbor leaf chlorophyll content QTLs responding to heat stress since they were only detected under heat stressed temperature and/or mapped using heat response of the trait. Previous studies also identified QTLs for heat stress tolerance traits, specifically at grain filling stage of wheat on chromosomes 2B, 2D, and 4A ( Paliwal et al, 2012 ; Acuña-Galindo et al, 2015 ; Bhusal et al, 2017 ). However, previous QTL studies conducted in wheat also identified QTLs for leaf chlorophyll content under heat stress on other chromosomes including 1B, 1D, 6A, and 7A ( Talukder et al, 2014 ), which were not detected at the seedling stage in the current study.…”

Incorporating Genome-Wide Association Mapping Results Into Genomic Prediction Models for Grain Yield and Yield Stability in CIMMYT Spring Bread Wheat

“…Due to the transformed genetic toolkit available in wheat, untangling the genetic architecture of traits by genome-wide association study (GWAS) and predicting performance by genomic selection (GS) have become feasible. Several GWAS analyses have been performed in wheat for plethora of traits including yield and yield components (Golabadi et al, 2011;Neumann et al, 2011;Bordes et al, 2014;Edae et al, 2014;Azadi et al, 2015;Assanga et al, 2017;Bhusal et al, 2017;Li et al, 2019). However, outcomes of these studies have hardly been applied in practical breeding programs.…”

Mapping QTLs for physiological and biochemical traits related to grain yield under control and terminal heat stress conditions in bread wheat (Triticum aestivum L.)

“…Four additive QTLs have been reported for chlorophyll content on chromosomes 1B, 2D, 3B and 7D in wheat in heat and drought stress conditions (Tahmasebi et al 2016). Major QTLs for heat tolerance have also been reported on chromosomes 2A and 2B in wheat under heat stress condition (Bhusal et al 2017). In complex traits, it is recognized that epistatic effects and QTL 9 environment interactions are important genetic components (Rebetzke et al 2007).…”