Genetic analysis of pre-harvest sprouting resistance in a wheat x spelt cross

Breeding for pre-harvest sprouting (PHS) resistance in wheat (Triticum aestivum L.) and spelt (Triticum spelta L.) is difficult because PNS is quantitatively inherited and strongly affected by environmental factors. The aim of this study was to detect molecular markers linked to quantitative trait loci (QTL) involved in PHS resistance to improve the breeding process. We measured falling number (FN) and alpha-amylase activity (AA) of 226 F-5 recombinant inbred lines (RILs) originating from a cross between the Swiss wheat cultivar Forno and the Swiss spelt cultivar Oberkulmer in four environments. QTL analysis was performed with 204 RILs and based on a genetic map of 183 loci. Across environments, 12 and 13 QTL were detected for FN and AA, respectively. Altogether the QTL explained more than 75% of the phenotypic variance. The two traits were highly correlated (r = -0.91) and of the 13 QTL for AA, nine coincided with QTL for FN. Three of the six QTL with major effects (R-2 greater than or equal to 15%) on PHS resistance coincided with QTL for ear length. The QTL with the strongest impact had the positive allele from Oberkulmer and was located on 5AL at the q locus, which is responsible for the typical ear morphology of spelt. The QTL on 6A (with the positive allele from Forno), 3B, and 7B (both with the positive allele from Oberkulmer) improve PHS resistance without changing the ear morphology, Thus, these QTL could be important for marker assisted selection for PHS resistance in both the wheat and the spelt germplasm.