Abstract
We have been questing florigen from physiological view points. Firstly, we applied the phloem sap collected from photoinduced Pharbitis nil cotyledons to vegetative P. nil, but no flower-inducing activity was detected. Secondly, the florigenic roles of several plant hormones were examined in P. nil by studying the endogenous levels and effects of the biosynthetic inhibitors, but only found that gibberellins and abscisic acid were involved in flower evocation. Then, we searched substances involved in the flowering regulated by factors other than photoperiodism. The stress-induced flowering of P. nil was inhibited by aminooxyacetic acid, and salicylic acid reverted this inhibition. However, salicylic acid did not induce flowering suggesting that salicylic acid and some unknown factor may induce flowering. Further, we found that DNA demethylation induced Perilla frutescens to flower through the production of transmissible flowering stimulus. This experimental system may be useful to study the florigen from molecular aspects.
