Identification of major quantitative trait loci for root diameter in synthetic hexaploid wheat under...

Synthetic hexaploid wheat (SHW) possesses numerous genes for resistance to stress, including phosphorus (P) deficiency. Root diameter (RDM) plays an important role in P-deficiency tolerance, but information related to SHW is still limited. Thus, the objective of this study was to investigate the genetic architecture of RDM in SHW under P-deficient conditions. To this end, we measured the RDM of 138 F₉ recombinant inbred lines derived from an F₂ population of a synthetic hexaploid wheat line (SHW-L1) and a common wheat line (Chuanmai32) under two P conditions, P sufficiency (PS) and P deficiency (PD), and mapped quantitative trait loci (QTL) for RDM using an enriched high-density genetic map, containing 120,370 single nucleotide polymorphisms, 733 diversity arrays technology markers, and 119 simple sequence repeats. We identified seven RDM QTL for P-deficiency tolerance that individually explained 11-14.7% of the phenotypic variation. Five putative candidate genes involved in root composition, energy supply, and defense response were predicted. Overall, our results provided essential information for cloning genes related to P-deficiency tolerance in common wheat that might help in breeding P-deficiency-tolerant wheat cultivars.