VARIATION IN TYPE AND RELATIVE AMOUNTS OF THE HIGH-MOLECULAR-WEIGHT GLUTENIN SUBUNITS IN DUTCH WHEAT-VARIETIES

The high molecular weight glutenin (HMWg) subunit genotypes and amount s of the individual subunits of 38 Dutch wheat varieties were determin ed. In winter wheat varieties, HMWg subunit alleles that, in general. have been shown to be related to a poor bread-making quality predomina ted. In spring wheat varieties, 'high-quality' alleles were most frequ ent. When examining the published HMWg subunit genotypes of British an d German varieties a similar difference was found in HMWg subunit geno type between spring and winter wheats. Because bread-making quality of spring wheat varieties is, in general, superior to that of winter whe ats, probably also because of the lower protein content of the latter, the two groups should be taken separately when studying the relation between HMWg subunit genotype and bread-making quality. There was a co nsiderable variation in relative amounts of allelic HMWg subunits and of subunits encoded by different genes (at the same or homeologous loc i). Between varieties with the same HMWg subunit genotype, relative am ounts of identical subunits differed only slightly. Some of these diff erences may reflect differences in gene expression, but it is not know n to what extent differences in genetic background or differences in g ene promoter are involved. There were differences in relative amounts of HMWg subunits encoded by alleles at the Glu-B1 locus. Here, an incr ease in relative amounts coincided with an increase in contribution to bread-making quality of an allele.