ИСТИНА

Light is foremost among environmental signals that modify transition to flowering in plants. It acts through the three main variables of quality, quantity, and duration. The role of quality and duration is well described, however, the precise molecular mechanisms by which irradiance, if acting through photosynthetic assimilation, can affect flowering transition is not clear. This investigation shows that the shape of chlorophyll (Chl) a fluorescence induction (FI) traces reflect transition to flowering in Arabidopsis thaliana (L.) Heynch. (ecotype Columbia). We have recorded the slow kinetics of Chl FI during the vegetative (leaf production) growth stage (GS), the inflorescence emergence GS and the flowering GS. Therefore, we suggest that kinetic of Chl FI reflects not only the inflorescence emergence growth stage, but the floral transition in Arabidopsis. Changes in the shape of the FI curve show clearly that reproductive development caused alteration of the thylakoids photofunctioning. Analysis of phenomenology and etiology of the various phases of the Chl FI patterns may help us to clarify the photosynthesis-dependent mechanisms that control floral development in Arabidopsis.