Abstract
The decrease in water resources is a serious threat to food security world-wide. In this regard, a genome-wide association study (GWAS) was conducted to identify grain yield and quality-related genes/loci under normal and water-deficit conditions. Highly significant differences were exhibited among genotypes under both conditions for all studied traits. Water-deficit stress caused a reduction in grains yield and an increase in grains protein contents (GPC) and gluten contents (GLC). Population structure divided the 96 genotypes into four sub-populations. Out of 72 significant marker-trait associations (MTAs), 28 and 44 were observed under normal and water-deficit stress conditions, respectively. Pleiotropic loci (RAC875_s117925_244, BobWhite_c23828_341 and wsnp_CAP8_c334_304253) for yield and quality traits were identified on chromosomes 5A, 6B and 7B, respectively, under normal conditions. Under a water-deficit condition, the pleiotropic loci (Excalibur_c48047_90, Tdurum_contig100702_265 and BobWhite_c19429_95) for grain yield per plant (GYP), GPC and GLC were identified on chromosomes 3A, 4A and 7B, respectively. The pleiotropic loci (BS00063551_51 and RAC875_c28721_290) for GPC and GLC on chromosome 1B and 3A, respectively, were found under both conditions. Besides the validation of previously reported MTAs, some new MTAs were identified for flag leaf area (FLA), thousand grain weight (TGW), GYP, GPC and GLC under normal and water-deficit conditions. Twenty SNPs associated with the traits were mapped in the coding DNA sequence (CDS) of the respective candidate genes. The protein functions of the identified candidate genes were predicted and discussed. Isolation and characterization of the candidate genes, wherein, SNPs were mapped in CDS will result in discovering novel genes underpinning water-deficit tolerance in bread wheat.
Highlights
Wheat is considered worldwide as one of the most important crops
High heritability was reported in the studied traits like grain yield per plant (GYP) (0.95), followed by Thousand-grain weight (TGW) (0.92), Flag leaf area (FLA) (0.90) and gluten contents (GLC) (0.90) which indicates (Table 2) that these are inherited traits and most likely the heritability is due to additive gene effects and selection may be effective in early generations for these traits
Our results showed that marker-trait associations (MTAs) for GLC were located on chromosomes 5A, 1B, 4B, 5B, 6B and 2D under normal conditions, while under water-deficit conditions reported on chromosomes 3A, 4A, 1B, 7B, 3D and
Summary
Wheat is considered worldwide as one of the most important crops. Ensuring sustainable wheat production to fulfill the needs of an increasing population is a serious challenge for wheat scientists and Agriculture 2020, 10, 392; doi:10.3390/agriculture10090392 www.mdpi.com/journal/agricultureAgriculture 2020, 10, 392 farmers under continuing variability in environmental circumstances [1]. Wheat is considered worldwide as one of the most important crops. Ensuring sustainable wheat production to fulfill the needs of an increasing population is a serious challenge for wheat scientists and Agriculture 2020, 10, 392; doi:10.3390/agriculture10090392 www.mdpi.com/journal/agriculture. The main causes of lower wheat production and poor grain quality are sowing methods, late cultivation, bad soil, uneven fertilizer doses, unsuitable weed eradicating, disease and less supply of water and heat [3]. Increasing human and livestock population and the modern lifestyle has directed new challenges for wheat breeders to develop wheat genotypes with specific seed quality, yield and resistance to drought, heat and diseases [4,5]. Wheat grain comprises protein range from 8 to 17% and gluten-forming proteins range from 75 to 85%
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