Genetic Analysis of Carbon Isotope Discrimination and its Relation to Yield in a Wheat Doubled Haploid Population

Carbon isotope discrimination (Δ13C) is considered a useful indicator for indirect selection of grain yield (GY) in cereals. Therefore, it is important to evaluate the genetic variation in Δ13C and its relationship with GY. A doubled haploid (DH) population derived from a cross of two common wheat varieties, Hanxuan 10 (H10) and Lumai 14 (L14), was phenotyped for Δ13C in the flag leaf, GY and yield associated traits in two trials contrasted by water availability, specifically, rain-fed and irrigated. Quantitative trait loci (QTLs) were identified by single locus and two locus QTL analyses. QTLs for Δ13C were located on chromosomes 1A, 2B, 3B, 5A, 7A and 7B, and QTLs for other traits on all chromosomes except 1A, 4D, 5A, 5B and 6D. The population selected for high Δ13C had an increased frequency of QTL for high Δ13C, GY and number of spikes per plant (NSP) when grown under rain-fed conditions and only for high Δ13C and NSP when grown under irrigated conditions, which was consistent with agronomic performance of the corresponding trait values in the high Δ13C progeny; that is, significantly greater than that in the low Δ13C. Therefore, selection for Δ13C was beneficial in increasing grain yield in rain-fed environments.