title: Allocation of absorbed light energy in PSII to thermal dissipations in the presence or absence of PsbS subunits of rice.
abstract: The thermal dissipation (TD) of absorbed light energy in PSII is considered to be an important photoprotection process in photosynthesis. A major portion of TD has been visualized through the analysis of Chl fluorescence as energy quenching (qE) which depends on the presence of the PsbS subunit. Although the physiological importance of qE-associated TD (qE-TD) has been widely accepted, it is not yet clear how much of the absorbed light energy is dissipated through a qE-associated mechanism. In this study, the fates of absorbed light energy in PSII with regard to different TD processes, including qE-TD, were quantitatively estimated by the typical energy allocation models using transgenic rice in which psbS genes were silenced by RNA interference (RNAi). The silencing of psbS genes resulted in a decrease in the light-inducible portion of TD, whereas the allocation of energy to electron transport did not change over a wide range of light intensities. The allocation models indicate that the energy allocated to qE-TD under saturating light is 30-50%. We also showed that a large portion of absorbed light energy is thermally dissipated in manners that are independent of qE. The nature of such dissipations is discussed.
authors.affiliation: Division of Integrated Life Sciences, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ishida
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Morita
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kishine
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takabayashi
authors.forename: Reiko
authors.initials: R
authors.lastname: Murakami
authors.forename: Satomi
authors.initials: S
authors.lastname: Takeda
authors.forename: Ko
authors.initials: K
authors.lastname: Shimamoto
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Endo
mesh_terms: D000042:Absorption / Q000528:radiation effects; D001483:Base Sequence; D004579:Electron Transport / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D008027:Light; D008954:Models, Biological; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects*; D010788:Photosynthesis / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D030821:Plants, Genetically Modified; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D013696:Temperature
chemical_list: D045332:Photosystem II Protein Complex; D021122:Protein Subunits