QTL for quality parameters for bread-making in a segregating wheat by spelt population

Abstract

Breeding for quantitatively inherited traits, e.g. quality parameters, is difficult on a phenotypic basis. Therefore, markers linked with QTL (quantitative trait loci) represent a promising tool to make the breeding process more efficient. We aim at estimating the number of genes involved in the phenotypic expression of the quality traits, localising these genes on a genetic map and studying their effects. This investigation will contribute towards a better understanding of spelt and wheat quality and will provide tools for a more efficient selection for quality within spelt and wheat breeding programs. As mapping population we used 226 F₅ Recombinant Inbred Lines (RILs) of a Triticum aestivum cv Forno × T. spelta cv Oberkulmer cross. For the characterisation of the phenotype the population and the parental lines were grown at three different environments (Fal96, Es96, Ros97). The harvested material was analysed for protein content and Zeleny sedimentation which correlates with the quantity and quality of the gluten. Grit was used for the determination of falling number reflecting the resistance to pre-harvest sprouting. Averaged over environments six QTL were found for protein content explaining 49% of the phenotypic variation, while one QTL (partR²=25%) located on 5A coincided with a QTL for Zeleny (part R²=26%). At both QTL the positive allele was from the spelt parent. Over all three locations a total of 14 QTL were detected for Zeleny explaining 45% of the phenotypic variation. Out of the 14 QTL for Zeleny seven were in common with QTL for specific Zeleny (ratio between Zeleny and protein content) and may, therefore, mainly influence the gluten quality. QTL analysis for falling number was performed over single environments due to the weak correlations between environments (r= 0.65). We detected nine QTL for pre-harvest sprouting resistance in Fal96 and six QTL in the environment Ros97 where high falling numbers were observed. In both environments all QTL together explained over 60% of the phenotypic variation. The most predominant QTL for this trait (part R²=45%) was situated on the long arm of chromosome 5A at the so called Q-locus. The high number of QTL for these three traits demonstrate the complex inheritance of baking quality and that several genes are responsible for the different baking quality of wheat and spelt. Therefore, we hope that bread-making quality can be improved in both crops by combining the positives alleles and that selection becomes more efficient by the use of markers linked with the QTL detected in this study.