QTL analysis of bread-making quality in wheat using a doubled haploid population

A set of 187 doubled haploid lines derived from the cross between cvs. Courtot and Chinese Spring was explored for QTLs for three bread-making quality tests: hardness, protein content and strength of the dough (W of alveograph). The scores of the parental lines were quite different except for protein content, and the population showed a wide range of variation. About 350 molecular and biochemical markers were used to establish the genetic map, and technological criteria were evaluated in 1 to 3 years. QTL detection was performed by the ”marker regression” method. The most significant unlinked markers were used in the model as covariates, and the results were tested by bootstrap resampling. For hardness, we confirmed a previously tagged major QTL on chromosome 5DS, and two additional minor QTLs were found on chromosome 1A and 6D, respectively. For protein content two main QTLs were identified on chromosomes 1B and 6A, respectively. For W, three consistent QTLs were detected: two at the same location as those for hardness, on chromosomes 1A and 5D; the third one on chromosome 3B. Therefore, it appeared that except for the Glu-1A locus, storage protein loci were not clearly involved in the genetic control of the criteria studied in the present work. Despite the reasonable size of the population no QTL with interactive effects could be substantially established as measured. All computations were carried out using home-made programmes in Splus language, and these are available upon request.