Abstract
Drought stress is a major constraint to wheat production worldwide, and root system architecture (RSA) plays a critical role in drought tolerance by influencing water uptake efficiency. This study aimed to dissect the genetic architecture of RSA traits and their relationship with drought tolerance in a diverse panel of 200 bread wheat accessions. A genome-wide association study (GWAS) was conducted using 15,000 single nucleotide polymorphism (SNP) markers to identify quantitative trait loci (QTL) associated with root length, root angle, root number, and root dry weight under well-watered and drought-stressed conditions. Additionally, drought tolerance indices including relative water content, chlorophyll content, and grain yield under drought were measured. We identified 42 significant QTL for RSA traits, of which 12 were co-localized with QTL for drought tolerance indices. Candidate genes underlying these QTL included transcription factors and genes involved in hormone signaling and cell wall modification. Notably, a QTL on chromosome 2B associated with root angle and yield under drought was validated in a biparental population. Our results provide insights into the genetic basis of RSA and its contribution to drought tolerance, offering targets for marker-assisted selection to improve wheat adaptation to water-limited environments.