EXPRESSION OF INDIVIDUAL HMW GLUTENIN SUBUNIT GENES OF WHEAT (TRITICUM-AESTIVUM L) IN RELATION TO DIFFERENCES IN THE NUMBER AND TYPE OF HOMOEOLOGOUS SUBUNITS AND DIFFERENCES IN GENETIC BACKGROUND

The amount of individual high-molecular-weight (HMW) glutenin subunits of bread-wheat has been studied in relation to variation at homoeolog ous loci and in the general genetic background. The relationships betw een Glu-1 loci have been studied using near-isogenic lines (NILs) of t he variety Sicco and in the progenies of two crosses. Substitution of the Sicco Glu-D1 allele by a null-allele resulted in higher amounts of the homoeologous subunits. The presence of a Glu-A1 null-allele did n ot have a noticeable effect on the amounts of homoeologous subunits. I n three out of four NILs and in the sister-lines of two crosses, the a mounts of HMW-subunits did not depend on the allele make-up at homoeol ogous loci. Only in the NIL which contains the Glu-D1 allele, encoding subunits 1Dx2.2 and 1Dy12, was the amount of homoeologous subunits lo wer than the amount of these subunits in Sicco. This study suggests a relation between the amount of HMW-subunits encoded by an allele and i ts contribution to bread-making quality. The effect of genetic backgro und has been studied using F4 and F5 lines of two crosses. The total a mounts of subunits, relative to the total amount of kernel proteins, s howed a considerable variation between lines. The ratio between indivi dual subunits did not differ between genetic backgrounds. Because this ratio is also largely independent of differences in environmental con ditions, it is concluded that the relative amount of a subunit is a va luable measure for the detection of genetically-determined differences in the expression of HMW-subunit genes.