Breeding driven enrichment of genetic variation for key yield components
and grain starch content under drought stress in winter wheat
Abstract
Drought is one of the major abiotic stress factors limiting wheat
production worldwide, thus threatening food security. The dissection of
the genetic footprint of drought stress response offers strong
opportunities toward understanding and improving drought tolerance in
wheat. In this study, we investigated the genotypic variability for
drought response among 200 diverse wheat cultivars (genotypes) using
agronomic, developmental, and grain quality traits, and conducted
genome-wide association studies (GWAS) to uncover the genetic
architectures of these important traits. Results indicated significant
effects of genotype, water regime and their interactions for all
agronomic traits. Grain yield was the most drought-responsive trait and
was highly correlated with kernels number per meter square. GWAS
revealed 17 and 20 QTL regions under rainfed and drought conditions,
respectively, and identified one LD block on chromosome 3A and two
others on 5D associated with breeding progress. The major haplotypes of
these LD blocks have been positively selected through breeding and are
associated with higher starch accumulation and grain yield under drought
conditions. Upon validation, the identified QTL regions caring favorable
alleles for high starch and yield will shed light on mechanisms of
tolerance to drought and can be used to develop drought resistant
cultivars.