Influence of Cotyledons upon α-Amylase Activity in Pea Embryonic Axes

Abstract

.alpha.-Amylase activity remained relatively low in the axes of intact etiolated pea [Pisum sativum] seedlings; the activity was predominantly confined to the epicotyl. Starch accumulated slightly. When the cotyledons were removed and the axes cultured on medium containing no C source, the starch reserve in the axes disappeared within a few days. This was accompanied by a 10- to 15-fold increase in .alpha.-amylase activity, in the absence of additional epicotyl growth. The phenomenon was observed for axes throughout early growth, although the relative accumulation of .alpha.-amylase activity in cultured axes was less for older seedlings. This change was attributed to a reduced response by nongrowing tissues. There was no corresponding change in .beta.-amylase activity. These observations, described for several varieties of peas, demonstrate the control of cotyledons upon the utilization of stored reserves within the axis, with .alpha.-amylase as a key enzyme.