Abstract
Higher plants change their photosynthetic antenna size upon acclimation to different light environments. In our previous studies, we revealed that expression of chlorophyllide a oxygenase (CAO) controls antenna size. Transgenic Arabidopsis plants overexpressing CAO have large antenna size and increased amounts of LHC proteins. To understand the roles of CAO proteins in light acclimation, we investigated the effects of alterations in CAO expression in the transgenic plants and ch1-1 mutant whose CAO gene is deleted. (1) The degree of thylakoid membrane stacking in the transgenic plants was same as that in the wild-type plants. ch1-1 lacks most of LHC proteins, but showed clear membrane stacking. (2) The de-epoxydation rate of xanthophyll-cycle pigments were higher in ch1-1 and lower in the CAO-overexpressing plants than that in the wild-type plants. Based on the results, we discuss the mechanism of light acclimation in higher plants.
