QTL analysis for grain colour and pre-harvest sprouting in bread wheat

A major objective in wheat breeding is the development of pre-harvest sprouting (PHS) tolerant wheat varieties with amber grain colour (GC), the latter being preferred both by the consumer in Asian markets, and by the processing industry globally. Quantitative trait loci (QTL) for these two traits were identified using a recombinant inbred line (RIL) population derived from an intervarietal cross, PHI 32 (red grain and PHS tolerant) x WL711 (amber grain and PHS susceptible). As many as 12 QTL for GC and 11 QTL for PHS were identified; 4 QTL for the two traits were co-localized. Most of the phenotypic variation (PV) for the two traits was explained by the main-effect QTL (M-QTL) having no interaction with environment, suggesting that selection may prove effective for improvement of both the traits. A major QTL for GC (PVE up to 40.42%), coincident with a minor QTL for PHS (PVE up to 8.10%), on the distal region of 3BL and a novel and major GC independent PHS QTL (PVE up to 29.47%) in proximal region of 6AL may prove useful for breeding PHS tolerant amber-grained wheat genotypes. Comparative genomic analysis revealed that the wheat genomic region carrying the major QTL for GC on 3BL is orthologous to a 1.63 Mb segment on rice chromosome 1, and the genomic region carrying the major QTL for PHS on 6AL is orthologous to a 5.47 Mb segment on rice chromosome 2. These rice genomic sequences may be exploited for fine mapping leading to map-based cloning of the above two major QTL, one each for GC and PHST. (C) 2009 Elsevier Ireland Ltd. All rights reserved.