MOLECULAR MARKERS ASSOCIATED WITH DIFFERENCES IN BREAD-MAKING QUALITYIN A CROSS BETWEEN BREAD WHEAT CULTIVARS WITH THE SAME HIGH M-R GLUTENINS

The association between molecular markers and bread-making quality (BM Q) was investigated in a cross between two wheat cultivars with the sa me high M-r-glutenin subunits but significantly different BMQ. A segre gant F-2 population was generated after crossing Klein 32 and Chinese Spring, and the BMQ of each FP-derived F, family was estimated using s odium dodecyl sulfate (SDS) sedimentation and mixograms. The same fami lies were characterized for II polymorphic loci using restriction frag ment length polymorphisms (RFLP) and single sequence repeats (SSR). Th ese loci were specifically selected for their complete or close linkag e to storage protein gene families. No significant differences in BMQ were detected at XGlu-B1 and XGlu-A1 loci using RFLP markers. Highly s ignificant (P<0.01) differences in all BMQ parameters were detected fo r 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 different iate the effect of XGli1 from that of XGlu3 because of the close linka ge between these two loci. These two loci, considered together, explai ned 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 th e model increased the proportion of variation in SDS sedimentation exp lained by the analysis up to 46% and the precision of the statistic an alysis up to 180%. Mixing parameters showed a lower correlation with p rotein content than SDS sedimentation parameters, and the increase in precision obtained by the use of the protein content as a covariable w as non-significant. (C) 1998 Academic Press Limited.