Overexpression of the violaxanthin de-epoxidase confers faster NPQ and photosynthesis induction in rice

Plants in the field experience fluctuations in light conditions. Plants with swift responses to dynamic light conditions usually gain competitive advantage in the field. The dynamic photosynthesis can be reflected in dynamic changes in almost all processes in photosynthesis, with dominant factors being dynamic changes in non-photochemical quenching, Rubisco activation and stomatal dynamics. Each of these dynamic responses is controlled by defined mechanisms. In this study, we showed that overexpression of VDE, an enzyme involved in the xanthophyll cycle and non-photochemical quenching, in rice resulted in faster NPQ induction, less photoinhibition, and faster photosynthesis induction, which together caused increased biomass production by about 11∼16%. This study, demonstrating a previously unnoticed role of VDE in altering the dynamics of photosynthesis induction besides decreasing photoinhibition, offers a potential strategy to improve canopy photosynthesis through capitalizing the ability of plants to use dynamic light. Highlight The overexpression of VDE in rice resulted in faster NPQ induction, less photoinhibition, and faster photosynthesis induction, which together caused increased biomass in field. ### Competing Interest Statement The authors have declared no competing interest. * NPQ : non-photochemical quenching LNC : leaf nitrogen content SLW : specific leaf weight CBB cycle : Calvin-Benson cycle Rubisco : ribulose 1,5-bisphosphate carboxylase/oxygenase RCA : Rubisco activase gm : mesophyll conductance gs : stomata conductance s : second h : hour m : minute Vio : violaxanthin Zea : zeaxanthin Ant : antheraxanthin Lut : lutein VDE : violaxanthin de-epoxidase ZEP : Zeaxanthin epoxidase PSII : photosystem II LHCII : light harvested complex II qE : energy-dependent quenching qZ : Zea-dependent quenching qI : photoinhibition-dependent quenching OE-VDE-1/3/5 : VDE overexpression lines WT : wild type HPLC : High Performance Liquid Chromatography DES : de-epoxidation state 1-qL : the redox state of QA Y(II) : the effective PS II quantum yield Y(NPQ) : the quantum yield of regulated energy dissipation in PSII Y(NO) : the quantum yield of nonregulated energy dissipation in PSII HL : high light A : CO2 assimilation rate MS : Morishige & Skoog Medium.