title: Genome-wide association analysis of agronomic traits in wheat under drought-stressed and non-stressed conditions.
abstract: This study determined the population structure and genome-wide marker-trait association of agronomic traits of wheat for drought-tolerance breeding. Ninety-three diverse bread wheat genotypes were genotyped using the Diversity Arrays Technology sequencing (DArTseq) protocol. The number of days-to-heading (DTH), number of days-to-maturity (DTM), plant height (PHT), spike length (SPL), number of kernels per spike (KPS), thousand kernel weight (TKW) and grain yield (GYLD), assessed under drought-stressed and non-stressed conditions, were considered for the study. Population structure analysis and genome-wide association mapping were undertaken based on 16,383 silico DArTs loci with < 10% missing data. The population evaluated was grouped into nine distinct genetic structures. Inter-chromosomal linkage disequilibrium showed the existence of linkage decay as physical distance increased. A total of 62 significant (P < 0.001) marker-trait associations (MTAs) were detected explaining more than 20% of the phenotypic variation observed under both drought-stressed and non-stressed conditions. Significant (P < 0.001) MTA event(s) were observed for DTH, PHT, SPL, SPS, and KPS; under both stressed and non-stressed conditions, while additional significant (P < 0.05) associations were observed for TKW, DTM and GYLD under non-stressed condition. The MTAs reported in this population could be useful to initiate marker-assisted selection (MAS) and targeted trait introgression of wheat under drought-stressed and non-stressed conditions, and for fine mapping and cloning of the underlying genes and QTL.
authors.affiliation: School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa.|Agricultural Research Council-Small Grain Institute (ARC-SGI), Bethlehem, South Africa.
authors.forename: Learnmore
authors.initials: L
authors.lastname: Mwadzingeni
authors.affiliation: School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa.
authors.forename: Hussein
authors.initials: H
authors.lastname: Shimelis
authors.affiliation: Agricultural Research Council-Biotechnology Platform, Pretoria, South Africa.
authors.forename: D Jasper G
authors.initials: DJ
authors.lastname: Rees
authors.affiliation: Agricultural Research Council-Small Grain Institute (ARC-SGI), Bethlehem, South Africa.
authors.forename: Toi J
authors.initials: TJ
authors.lastname: Tsilo
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D002874:Chromosome Mapping; D055864:Droughts; D018745:Genome, Plant; D055106:Genome-Wide Association Study; D005838:Genotype; D015810:Linkage Disequilibrium; D010641:Phenotype; D000069600:Plant Breeding; D040641:Quantitative Trait Loci; D019655:Quantitative Trait, Heritable; D013312:Stress, Physiological / Q000235:genetics*; D014908:Triticum / Q000235:genetics*