Abstract
Light energy is excessive at low temperature due to lowered activity of CO2 fixation. Higher plants have multiple mechanisms to adapt low temperature, including accumulation of pigments, carotenoids and anthocyanins, and modification of LHCII composition. In order to characterize the molecular bases of the adaptation to excessive light energy under low temperature conditions, Arabidopsis thaliana plants were treated with continuous low-temperature or fluctuating-temperature conditions. There was no significant different in maximum activity of photosystem II (Fv/Fm). However, the fluctuation of temperature modified the light-intensity-dependence of NPQ. Based on this information, mutans defective in the regulation of photosynthetic electron flow under low temperature were screened using chlorophyll fluorescence imaging. The mutants defective in PS I cyclic electron transport pathway were also characterized.
