Discovery of quantitative trait loci for crossability from a synthetic wheat genotype

Crossability between wheat and rye is an important trait for wheat improvement. No quantitative trait loci (QTLs) were detected from wheat ancestors previously. The objectives of this study were to dissect the QTLs for crossability using 111 introgression lines (ILs) derived from synthetic hexaploid wheat. A total of 1275 SSR markers were screened for polymorphism between the two parents, and 552 markers of them displayed polymorphism, of which 64 were selected for genotyping the 111 BC(5)F(6) ILs. Field trials were performed in a Latinized α-lattice design in Luoyang and Jiaozuo of Henan Province of China in 2007-2008 and 2008-2009 cropping seasons. One-way ANOVA and interval mapping (IM) analysis were used to detect QTL for crossability between wheat and rye. A total of 13 putative QTLs were detected. Five of them, QCa.caas.1A, QCa.caas.2D, QCa.caas.4B, QCa.caas.5B and QCa.caas.6A, were detected in both trials and three of them, QCa.caas.2D, QCa.caas.4B and QCa.caas.6A, were novel. The positive effect allele of the four QTLs came from the donor parent Am3 except QCa.caas.6A that came from the recurrent parent Laizhou953. ILs with both higher positive effect alleles and favorable agronomic traits developed in present study are elite germplasm for wide crossing in wheat. Results from the current study suggest that wheat ancestors can be rich in new sources of crossability genes.