Abstract
Regulation of the antenna size plays an essential role in long-term acclimation to changing light environments. The antenna size is primarily determined by the level of light-harvesting chlorophyll a/b complex (LHC) assembled to photosystems. When low light acclimated plants are transferred to high light conditions, the LHCII decrease resulting in a smaller antenna size. This indicates that the degradation of LHCII is the key step in the acclimation to high light condition. Previously we reported that chlorophyll b reductase catalyzes the first step of LHCII degradation. In this study, we examined the function of chlorophyll b reductase in the acclimation to high-light condition. Chlorophyll b reductase has two isoforms, NYC1 and NOL, in Arabidopsis genome. Upon transfer to high light condition, LHCII begun to degrade in WT and nol mutant, but LHCII remained at high level in nyc1 mutant and nyc1/nol double mutants. WT and nol mutant retained photosynthesis activity but nyc1 mutant and nyc1/nol double mutant suffered from severe photodamages upon the transition to high light. These results suggest that NYC1 plays and crucial role in the acclimation to high light conditions.
