Regulation of high pI alpha-amylase synthesis in wheat aleurone by a gene(s) located on chromosome 6B

Synthesis of high and low pI alpha-amylase in germinating wheat grains and GA(3)-treated de-embryonated grains of Chinese Spring (CS) and its diteloso mic derivative (CS dit 6BS) were compared and related to high pI alpha-amyl ase production in grains affected by late maturity alpha-amylase (LMA). In de-embryonated grains of CS dit 6BS (lacking the long arm of chromosome 6B) treated with GA(3), synthesis of high pI alpha-amylase isozymes controlled by Amy-1 genes on chromosomes 6A and 6D was dramatically reduced compared to Chinese Spring. The results suggest the presence of a gene(s) on the lon g arm of chromosome 6B, which is (are) required for GA-induced alpha-amylas e synthesis in the aleurone. Similarly, in wheat grains affected by LMA, hi gh pI alpha- Amy genes on the group 6 chromosomes are activated apparently by a single gene, tentatively located on chromosome 6B. Both genes may be p art of the GA-induced amylase synthesis pathway in the aleurone. By contras t, synthesis of the high pI alpha-amylase isozymes in the early stages of g ermination of CS dit 6BS grains was very similar to CS. This contrast betwe en GA(3)-treated de-embryonated grains and germinating grains could be expl ained by control of alpha-amylase synthesis in scutellum in the early stage s of germination being different to that in GA(3)-treated aleurone.