title: Light energy allocation at PSII under field light conditions: how much energy is lost in NPQ-associated dissipation?
abstract: In the field, plants are exposed to fluctuating light, where photosynthesis occurs under conditions far from a steady state. Excess energy dissipation associated with energy quenching of chlorophyll fluorescence (qE) functions as an efficient photo-protection mechanism in photosystem II. PsbS is an important regulator of qE, especially for the induction phase of qE. Beside the regulatory energy dissipation, some part of energy is lost through relaxation of excited chlorophyll molecules. To date, several models to quantify energy loss through these dissipative pathways in PSII have been proposed. In this short review, we compare and evaluate these models for PSII energy allocation when they are applied to non-steady state photosynthesis. As a case study, an investigation on energy allocation to qE-associated dissipation at PSII under non-steady state photosynthesis using PsbS-deficient rice transformants is introduced. Diurnal and seasonal changes in PSII energy allocation in rice under natural light are also presented. Future perspective of studies on PSII energy allocation is discussed.
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan. Electronic address: tuendo@kais.kyoto-u.ac.jp.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Endo
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Uebayashi
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ishida
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ikeuchi
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D002940:Circadian Rhythm; D004579:Electron Transport; D004735:Energy Transfer; D008027:Light; D009154:Mutation; D012275:Oryza / Q000378:metabolism* / Q000528:radiation effects; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D012621:Seasons
chemical_list: D045332:Photosystem II Protein Complex; D002734:Chlorophyll
keywords: Electron transport; Energy dissipation; NPQ; Photosystem II; PsbS