Development and characterization of near‐isogenic lines for quantitative trait locus <i>qDT.3B.1</i> underlying drought tolerance in wheat

Drought is a critical challenge to wheat (Triticum aestivum L.) productivity. The quantitative complexity of drought tolerance makes breeding for this trait difficult. Developing near-isogenic lines (NILs) targeting quantitative trait locus (QTL) for 1000-grain weight (TGW) under drought stress can effectively identify key mechanisms and genes. Using the heterogeneous inbred family method and a fast-generation cycling system, we developed wheat NILs targeting TGW QTL on chromosome 3B and characterized them under drought and well-watered conditions. Genotyping the NILs using 90K single nucleotide polymorphism (SNP) array, we narrowed down the targeted QTL region and identified four SNP markers near the target QTL linked with six candidate genes. These candidate genes encode beta-glucuronosyltransferase, ABC transporter, transmembrane protein, F-box protein, cytochrome P450, and alanine-tRNA ligase associated with functions related to responses under drought stress. In silico expression analysis revealed that all these candidate genes were highly expressed in root and grain tissues under drought stress and involved in pathways such as ubiquitin-mediated proteolysis, metabolic pathways and biosynthesis of various N-glycan, steroids, and secondary metabolites emphasizing its potential role affecting grain weight under drought stress. This study offers insights into markers and genes controlling TGW under drought and has potential for advancing the development of high-yielding resilient wheat cultivars.