Abstract
Three pigments, violaxanthin, antheraxanthin and zeaxanthin, are involved in xanthophyll cycle, which is a mechanism for adaptation to high light in plants. The pool size of xanthophyll cycle pigments increases in the process of acclimation to high light for hours or days.The photosynthetic electron transport chain becomes reduced under high light conditions. The expression of some photosynthesis-related genes is known to be regulated by the plastoquinone redox state.In a similar way, we proposed that the redox state is involved in the regulation of xanthophyll cycle's pool size.To prove such a hypothesis, we regulated the redox state by adding a low concentration of DCMU to cell cultures of Arabidopsis and analyzed its effect on xanthophyll cycle synthetic enzymes and pigments.The xanthophylls' pool size of cells grown under high light conditions did not increase after the DCMU treatment.Although the transcript level of β-carotene hydroxylase genes was higher under high light conditions, the DCMU treatment blocked this effect.We propose that the xanthophyll cycle pigments' pool size is regulated by the redox state of the photosynthetic electron transport chain.
