Molecular markers associated with differences in bread-making quality in a cross between bread wheat cultivars with the same high Mr glutenins

The association between molecular markers and bread-making quality (BMQ) was investigated in a cross between two wheat cultivars with the same high M-r-glutenin subunits but significantly different BMQ. A segregant F-2 population was generated after crossing Klein 32 and Chinese Spring, and the BMQ of each FP-derived F, family was estimated using sodium dodecyl sulfate (SDS) sedimentation and mixograms. The same families were characterized for II polymorphic loci using restriction fragment length polymorphisms (RFLP) and single sequence repeats (SSR). These loci were specifically selected for their complete or close linkage to storage protein gene families. No significant differences in BMQ were detected at XGlu-B1 and XGlu-A1 loci using RFLP markers. Highly significant (P<0.01) differences in all BMQ parameters were detected for XGli-B1 and XGlu-B3 loci on chromosome arm IBS. The increase in the number of Klein 32 alleles at these loci determined a linear increase in sedimentation and mixogram values. It was not possible to differentiate the effect of XGli1 from that of XGlu3 because of the close linkage between these two loci. These two loci, considered together, explained from 11 to 15% of the variation in BMQ observed in this cross. The inclusion of the protein content of each sample as a covariable in the model increased the proportion of variation in SDS sedimentation explained by the analysis up to 46% and the precision of the statistic analysis up to 180%. Mixing parameters showed a lower correlation with protein content than SDS sedimentation parameters, and the increase in precision obtained by the use of the protein content as a covariable was non-significant. (C) 1998 Academic Press Limited.