CHANGES IN POLYAMINE BIOSYNTHESIS DURING THE INITIAL-STAGES OF TUBERIZATION IN POTATO (SOLANUM-TUBEROSUM L)

The levels of the diamine, putrescine, the polyamines, spermidine and spermine, and the activities of the associated biosynthetic enzymes, a rginine decarboxylase, ornithine decarboxylase and S-adenosyl-L-methio nine decarboxylase were determined in various organs of the potato pla nt at a number of early tuberisation stages. The levels of spermidine and spermine and the biosynthetic enzymes all increased during the ini tial tuberisation stages and then decreased as the tuber increased in size. Levels of putrescine fell continuously in the stolon tip and in tubers as tuberisation proceeded. In other organs (root, leaf and stem ) polyamine levels and enzyme activities were much lower.