PRODUCTION OF α-AMYLASES IN GERMINATING WHOLE AND INCUBATING DE-EMBRYONATED BARLEY KERNELS*

α-Amylases produced in germinated barley and incubated de-embryonated barley kernels (cv. Bonanza), in the absence and presence of gibberellic acid (GA₃), were analyzed qualitatively by polyacrylamide gel isoelectric focusing (PAG-IEF) and quantitatively by chromatofocusing. Identical patterns of α-amylase components were obtained for both germinated barley and incubated de-embryonated barley kernels at each germination/incubation stage, in the absence or presence of GA₃. Total α-amylase increased rapidly in the germinating whole seed whereas in the incubating de-embryonated grain the α-amylase activity increase was much slower. Addition of exogenous GA₃ did not induce production of higher levels of α-amylase in either the germinating whole or incubating de-embryonated barley kernel. Quantitative chromatofocusing analysis revealed that the proportion of α-amylase III to α-amylase II activity decreased linearly with germination time in the whole grain but remained constant in the incubating de-embryonated grain in the absence or presence of GA₃. The major proportion of α-amylase activity in the germinating whole grain and incubating de-embryonated grain was synthesized in the form of α-amylase II components. However, α-amylase I represented a larger proportion of the total α-amylase activity produced in the incubating de-embryonated grain, as compared to the germinating whole seed in the absence or presence of GA₃. These results suggest that embryo excision differentially affects production of α-amylase II as compared to α-amylase I.