Gene dosage effect of the wheat Wx alleles and their interaction on amylose synthesis in the endosperm

To find out gene dose effect of each of the three homoeologous Wx genes and their interaction on the production of granule-bound starch synthase (GBSS I) and amylose biosynthesis in the endosperm, Chinese Spring and its near-isogenic waxy types were crossed reciprocally and, obtained a plant population with varying doses of each Wx gene. The amount of GBSSI was increased linearly with increasing gene dose of either of Wxloci. In each of the three Wx loci, the change in amylose content was linear up to 3 doses, with a more potent capacity ofWx-B1a at any dose. Higher level of amylose production was observed in the reciprocal F1 grains than the expected effect of dose/s of each gene or additive effect of different allelic combination by artificially blend starches which have amylose produced by equivalent number ofWx alleles to that of relevant F1 cross. When Wx-B1a and Wx-A1a were combined, increase in amylase content was not in proportion to increase in gene dosage. The enhanced amylase synthesis was shown by 2-gene and 3-geneinteraction, indicating that not only type of the three Wx genes and its dose but the interaction among them have significant roles in determining the amylose content.