Effects of spermidine on the synthesis of α‐amylase in cotyledons of mung bean seedlings

When cotyledons of mung bean [Vigna radiata (L.) Wilczek] were treated with spermidine (3 mM) during the first 6 h of imbibition, the development of α‐amylase activity in cotyledons during the following 3 days was severely inhibited (75%) This inhibition was due to a slower accumulation of α‐amylase protein, which in turn resulted from an inhibition of α‐amylase synthesis. The rise in the level of α‐amylase mRNA in cotyledons was also inhibited by spermidine treatment. However, the degree of inhibition of mRNA accumulation (40%) was not so marked as that of the activity of α‐amylase synthesis (80%). These results are discussed in relation to the mode of action of spermidine on α‐amylase expression.