Changes in polyamine contents and arginine decarboxylase activity associated with elongation growth of hypocotyls in Rhizophora apiculata Bl.

Changes in polyamine (putrescine, spermidine, spermine) contents and arginine decarboxylase activity in three different regions of developing hypocotyls of Rhizophora apiculata Bl. were analyzed. Among the three polyamines, spermidine was present in higher quantities than either putrescine or spermine. Spermine occurred in the lowest quantities. Spermidine declined rapidly with the age of the hypocotyl. In contrast, a marked increase in putrescine was observed with the age of the hypocotyl. Arginine decarboxylase activity increased during the various developmental stages of hypocotyl growth, particularly in the final stage. The results suggest that putrescine plays a major role in the growth of the hypocotyl as evidenced by simultaneous increase in the content of putrescine and arginine decarboxylase activity.