Regulation of high pI α-amylase synthesis in wheat aleurone by a gene(s) located on chromosome 6B
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Synthesis of high and low pI α-amylase in germinating wheat grains and GA3-treated de-embryonated grains of Chinese Spring (CS) and its ditelosomic derivative (CS dit 6BS) were compared and related to high pI α-amylase production in grains affected by late maturity α-amylase (LMA). In de-embryonated grains of CS dit 6BS (lacking the long arm of chromosome 6B) treated with GA3, synthesis of high pI α-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 long arm of chromosome 6B, which is (are) required for GA-induced α-amylase synthesis in the aleurone. Similarly, in wheat grains affected by LMA, high pI α- Amy genes on the group 6 chromosomes are activated apparently by a single gene, tentatively located on chromosome 6B. Both genes may be part of the GA-induced amylase synthesis pathway in the aleurone. By contrast, synthesis of the high pI α-amylase isozymes in the early stages of germination of CS dit 6BS grains was very similar to CS. This contrast between GA3-treated de-embryonated grains and germinating grains could be explained by control of α-amylase synthesis in scutellum in the early stages of germination being different to that in GA3-treated aleurone.
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