Localization of amylase activity in cotyledons of germinated mung bean seeds

Abstract

Developmental patterns of amylase activity in mung bean (Vigna radiata) cotyledons were observed by histochemical methods. In axis-attached cotyledons, the development of amylase activity and the decompostion of starch grains occurred first in cells located farthest from vascular bundles, and 3 days after imbibition, starch granules appeared to remain intact only in two to three cell layers around the vascular bundles. In axis-detached cotyledons, on the other hand, no conspicuous change in amylolytic activity was detected. When cotyledons were allowed to imbibe water through the surface not covered by the seed coat, amylase activity developed, even if they were detached from the axis. However, the developmental patterns of the activity were quite different from those with attached cotyledons; high amylase activity was detected in the cell layers beneath the epidermis of the surface not covered by the seed coat. These histochemical observations are related to previous results of biochemical experiments. Key words: amylase development, cotyledons, germination, histochemistry, mung bean, Vigna radiata.