QTL mapping for root traits during post-tillering stage under moisture-deficit stress in wheat

Root traits during post-tillering stages in wheat are critical for adapting to moisture-deficit stress. This study mapped 24 traditional quantitative trait loci (QTLs) of root and yield traits in wheat across 14 chromosomes using 198 recombinant inbred lines (RILs), developed by crossing two contrasting parents, HD 3086 and HI 1500. Genotyping was done with the 35 K Axiom Wheat Breeder's Array, followed by QTL mapping through Inclusive Composite Interval Mapping (ICIM) software. From the 5 conditional QTLs (Y75|Y45) mapped, QARFC.iari-2 A was mapped as the major stable QTL for root fresh weight, explaining 11.23% of the phenotypic variance, indicating its direct genetic effects during 75 days after sowing. Additionally, the chromosomal region of 6 A (flanked by the markers AX-94646424 and AX-94974293) was linked to six traits indicating its pleiotropy. Candidate gene TraesCS5A03G0005300, an ethylene receptor, was identified in QRSL.iari-5 A, affecting root-shoot length ratio. Multi-trait indices MGIDI (Multi-Trait Genotype-Ideotype Distance Index), FAI-BLUP (Factor Analysis and Ideotype-design with Best Linear Unbiased Prediction), and SHI (Smith-Hazel index) identified three common RILs (RIL-53, RIL-56 and RIL-123) suitable for breeding programmes. These identified QTLs can be utilised for marker-assisted selection (MAS) in future breeding programmes after successful validation.