Mapping QTLs for Seminal Root Architecture and Coleoptile Length in Wheat

Abstract

Root system is important for belowground nutrients acquisition, and is also an important part to respond to drought stress. The purpose of this study was to dissect the genetic basis of seminal root architecture and coleoptile length of wheat by mapping quantitative trait loci (QTLs) of target traits. A doubled haploid (DH) population with 150 lines derived from a cross between two common Chinese wheat varieties Hanxuan 10 and Lumai 14 was used as the plant materials. Gel-chamber was em- ployed to evaluate seminal root architecture traits, including maximum root length (MRL), root number (RN), total root length (TRL), root diameter (RD), root angle (RA), ratio of root dry weight to shoot dry weight (RDW/SDW), and coleoptile length (CL) of seedlings. QTLs for these traits were detected using mixed-model-based composite interval mapping method. A total of 12 additive-effect QTLs and 7 pairs of additive × additive QTLs associated with the target traits were mapped on chromosomes 1A, 1B, 2B, 2D, 3B, 4A, 4D, 5A, 5B, 6A, 7A, and 7B. The phenotypic variation explained by individual additive-effect QTL varied from 5.64% to 12.37%. The additive effects ranged from 0.02 to 8.45. The phenotypic variation explained by each pair of epistatic QTLs varied from 8.70% to 15.90%. The epistatic effects ranged from 0.20 to 7.45. Two QTL clusters for seedling root traits were detected on chromosomes 3B and 7A. These results would be helpful to maker-assisted selection of seminal root architecture and coleoptile.