SIGNIFICANCE OF SPERMIDINE IN THE INITIATION OF ADVENTITIOUS BUDS IN STEM SEGMENTS OF TORENIA

When stem segments of Torenia fournieri Lind. were cultured in vitro, the initiation of adventitious buds, which is usually induced by cytok inin, was induced by application of polyamines, such as putrescine and spermidine. Addition of arginine had a slight inductive effect. When cyclohexylamine, an inhibitor of spermidine synthase, was added simult aneously with putrescine, induction of the initiation of buds by putre scine was strongly inhibited. However, application of the inhibitor to gether with spermidine had no effect on the spermidine-induced initiat ion of buds. The induction of initiation of buds by a cytokinin, by a calcium ionophore, by cyclic AMP, and by a phorbol ester, which was ac companied in each case by elevation of the levels of endogenous spermi dine, was also inhibited by cyclohexylamine. These results suggest the involvement of spermidine in the initiation of adventitious buds in s tem segments of Torenia.