RHYTHMIC OSCILLATION OF CYCLIC 3',5'AMP AND -GMP CONCENTRATION AND STIMULATION OF FLOWERING BY CYCLIC 3',5'-GMP IN Lemna paucicostata 381

Abstract— Rhythmic oscillation of the concentration of cyclic 3',5'-AMP and -GMP in a short day plant, Lemna paucicostata 381 in continuous darkness was detected after 2 cycles of 12 h dark and 12 h light entrainment. Cyclic 3',5'-AMP and -GMP, extracted from whole plant showed parallel oscillations in their concentrations for initial 36 h in continuous darkness and the oscillation in the concentration of cyclic 3',5'-AMP was roughly circadian. Their concentrations decreased during the initial 12 h (subjective night) and increased during 12 to 28 h. Exogenous addition of 2 μ.M of cyclic 3',5'-GMP or the dibutyryl derivative of it stimulated floral induction by 20 to 30%, when the plants were grown under 12 h light and 12 h dark regime. Cyclic 3',5'-AMP or the dibutyryl derivative of it showed little effect on flowering.