Characterization of the Amylolytic Activity of Araucaria araucana (Mol.) Koch Germinating Seeds

概要

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Starch is the main reserve in Araucaria araucana (Mol.) Koch seeds. In an attempt to understand the regulation of starch mobilization during seed germination, amylase activity was characterized and its levels were measured for the first 90 h after the start of seed imbibition. Amylase is present in both the embryo and megagametophyte when seeds are quiescent. The enzyme activity of the embryo has two peaks during the 90 h, while amylase activity of the megagametophyte remains low and unchanged during this time. Analysis of the products released by the enzyme and thermostability experiments identify the amylase as α-amylase. Differential centrifugation of embryo homogenates under isoosmotic conditions shows that the enzyme is soluble. Quantification of the endogenous gibberellins of the embryo shows a time correlation between the rise in amylase activity and the rise in specific gibberellin levels during the 40 h after the start of imbibition. The growth retardant AMO-1618 lowers enzyme activity to 37.3% of the control at this time. However, activity is almost completely restored when the gibberellins from embryonic tissue are added in physiological doses to the imbibition medium containing AMO-1618.
日本植物生理学会の論文