Evidence against an involvement of cyclic nucleotides in the induction of betacyanin synthesis by cytokinins.

1. A wide range of purine bases, nucleosides and cyclic nucleotides were shown to induce betacyanin synthesis in Amaranthus seedlings. 2. The induction of pigment by benzyladenine, dibutyryl cyclic AMP or cyclic AMP was not potentiated by aminophylline. Aminophylline was shown to inhibit Amaranthus cyclic AMP phosphodiesterase activity. 4. Incubation of seedlings with aminophylline inhibited the conversion of 6-[G--3H]benzyladenine into presumed 9- and 7-glucosylbenzyladenine. 5. Induction of betacyanin synthesis by 6-benzyladenine or by exposure to red light was not accompanied by changes in the total cyclic AMP content in seedlings. 6. It is concluded that the inducers tested act as cytokinin analogues; no evidence was obtained to support cyclic AMP as an intermediate in the induction process.