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. Cour tot and Chinese Spring was explored for QTLs for three bread-making quality tests: hardness, protein content and strength of the dough (W of alveograp h). The scores of the parental lines were quite different except for protei n content, and the population showed a wide range of variation. About 350 m olecular and biochemical markers were used to establish the genetic map, an d 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 b y bootstrap resampling. For hardness, we confirmed a previously tagged majo r QTL on chromosome 5DS, and two additional minor QTLs were found on chromo some 1A and 6D, respectively. For protein content two main QTLs were identi fied on chromosomes 1B and 6A, respectively. For W, three consistent QTLs w ere detected: two at the same location as those for hardness, on chromosome s 1A and 5D; the third one on chromosome 3B. Therefore, it appeared that ex cept for the Glu-1A locus, storage protein loci were not clearly involved i n 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 ou t using home-made programmes in Splus language, and these are available upo n request.