An integrated multiple analysis reveals the genetic information associated with root-related traits in wheat...

Combined single nucleotide polymorphisms (SNPs) and structural chromosome variations (SCVs), genomic regions associated with root angles (RAs), root numbers (RNs), and root dimensions (RDs) at adult stage were detected by multiple analyses, and a novel locus, QRD.sxau.6B.4, was finely mapped, providing valuable insights for assisting in the development of breeding programs for root-related traits in wheat. Roots play a crucial role in absorption of water and minerals, impacting agronomic traits and yield. While direct measurements of root phenotypes in the field are time-consuming and labour-intensive, identifying root phenotypes on a large scale and analysing their genetic basis are essential. The present study investigated RAs, RNs, and RDs at adult stage and integrated association and linkage analyses, using SNPs and SCVs, to dissect root-related traits. The results indicated that three root-related traits exhibited abundant phenotypic variations in both populations. Notably, RNs, RAs, and RDs significantly decreased over the years of release, with decreases of 13.49%, 16.70%, and 50.95%, respectively. Identification of seedling root biomass may provide a reference for determining RA and RD at adult stage. A total of 25 (SNPs) and 15 (SCVs) significant loci in two populations were identified, explaining 3.21% to 16.61% of phenotypic variation. An epistasis analysis revealed an interaction between QRN.sxau.1D.3 and QRN.sxau.2A.1 related to RN, while no epistatic effects were observed in other loci regions. The QRD.sxau.6B.4/PAV.6B overlapped in the same genomic region by association panel and doubled haploid (DH) population, explaining 5.19% to 9.75% of phenotypic variations. In secondary mapping population, fine mapping of QRD.sxau.6B.4 narrowed functional region down to 8.48 Mb region combining RD and genotypes. Two introgression lines were used to demonstrate the significant potential of PAV.6B for root improvement. The results of present study provide novel insights into genetic mechanisms governing root development at adult stage in wheat.