Abstract
Understanding the genetic basis of drought tolerance in safflower (Carthamus tinctorius L.) is essential for developing resilient varieties. In this study, we performed a genome-wide association study (GWAS) using DArTseq markers to identify marker-trait associations (MTAs) linked to drought tolerance across 90 globally diverse safflower genotypes. These genotypes were evaluated under both rainfed (drought) and irrigated conditions over three consecutive years (2016-2018). Significant variation in seed yield and morphological traits was observed between genotypes and across environments, with notably reduced performance under rainfed conditions. A total of 66 MTAs were identified for key agronomic traits, including seed yield, 1000-seed weight, number of heads per plant, and days to maturity, with 45 MTAs showing significant associations with the stress-tolerance index (STI). Twelve MTAs were consistently detected across both stress and non-stress conditions, suggesting stable loci for breeding applications. BLAST searches indicated that several identified markers corresponded to genes involved in abiotic stress response, including biotin carboxylase, serine/threonine-protein kinase, and zinc finger domain proteins. The clustering of genotypes based on drought-tolerance coefficient (DC) and STI values grouped genotypes into drought-susceptible and drought-tolerant categories, with no strong correlation to geographic origin. These findings provide valuable insights into the genetic architecture of drought tolerance in safflower and highlight candidate loci for marker-assisted selection, supporting the development of drought-resilient varieties.