Abstract
Multi-locus genome wide association study was undertaken using a set of 320 diverse spring wheat accessions, which were each genotyped for 9,626 SNPs. The association panel was grown in replicated trials in four environments [two each in irrigated (IR) and rainfed (RF) environments], and phenotypic data were recorded for five traits including days to heading, days to maturity, plant height, thousand grain weight and grain yield. Forty-six significant marker-trait associations (MTAs) were identified for five traits. These included 20 MTAs in IR and 19 MTAs in RF environments; seven additional MTAs were common to both the environments. Five of these MTAs were co-localized with previously known QTL/MTAs and the remaining MTAs were novel and add to the existing knowledge. Three desirable haplotypes for agronomic traits, one for improvement in RF environment and two for improvement in IR environment were identified. Eighteen (18) promising candidate genes (CGs) involved in seven different biological activities were also identified. The expression profiles of four (Trehalose-6-Phosphate, APETALA2/Ethylene-responsive factor, DNA-binding One Zinc Finger and Gibberellin-dioxygenases) of the 18 genes showed that they were induced by drought stress in the wheat seedlings. The MTAs, haplotypes and CG-based markers may be used in marker-assisted breeding for drought tolerance in wheat.
Highlights
Genetic basis of drought tolerance has been studied in several crops
The Wheat association mapping panel grown under different water regimes [i.e. irrigated (IR) and rainfed (RF] during growing seasons (2011–12 and 2012–13) and phenotypic data were collected for five different traits
It is widely known that drought tolerance is a complex quantitative trait that is influenced by genetic background and environmental conditions
Summary
Genetic basis of drought tolerance has been studied in several crops. In Arabidopsis SWI2/SNF2 remodeling was found to maintain equilibrium between plant growth and drought stress tolerance[8]. A number of studies involving QTL analysis for different agronomic traits including grain yield and its component traits under favourable and stress (e.g. rainfed, drought, heat) environments were conducted in the recent past. These involved interval mapping and genome wide association studies (GWAS) in hexaploid and durum wheat[16]. The present study was conducted to identify MTAs involving yield and related traits using LD-based multi-locus GWA mapping using GBS (genotyping by sequencing)-derived SNP markers in a large association panel consisting of 320 spring wheat accessions. The results from the present study should prove useful for genetic improvement of yield and yield contributing traits via marker-assisted breeding to enhance productivity under limited water availability
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