title: Regulation of photochemical energy transfer accompanied by structural changes in thylakoid membranes of heat-stressed wheat.
abstract: Photosystems of higher plants alleviate heat-induced damage in the presence of light under moderate stressed conditions; however, in the absence of light (i.e., in the dark), the same plants are damaged more easily. (Yamauchi and Kimura, 2011) We demonstrate that regulating photochemical energy transfer in heat-treated wheat at 40 °C with light contributed to heat tolerance of the photosystem. Chlorophyll fluorescence analysis using heat-stressed wheat seedlings in light showed increased non-photochemical quenching (NPQ) of chlorophyll fluorescence, which was due to thermal dissipation that was increased by state 1 to state 2 transition. Transmission electron microscopy revealed structural changes in thylakoid membranes, including unstacking of grana regions under heat stress in light. It was accompanied by the phosphorylation of thylakoid proteins such as D1 and D2 proteins and the light harvesting complex II proteins Lhcb1 and Lhcb2. These results suggest that heat stress at 40 °C in light induces state 1 to state 2 transition for the preferential excitation of photosystem I (PSI) by phosphorylating thylakoid proteins more strongly. Structural changes of thylakoid membrane also assist the remodeling of photosystems and regulation of energy distribution by transition toward state 2 probably contributes to plastoquione oxidation; thus, light-driven electrons flowing through PSI play a protective role against PSII damage under heat stress.
authors.affiliation: Graduate School of Agricultural Science, Kobe University, 657-8501 Kobe, Japan. yoko.marutani@stu.kobe-u.ac.jp.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Marutani
authors.affiliation: Graduate School of Agricultural Science, Kobe University, 657-8501 Kobe, Japan. yamauchi@kobe-u.ac.jp.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yamauchi
authors.affiliation: Faculty of Agriculture, Kobe University, 657-8501 Kobe, Japan. miyoshi.akihito.53v@st.kyoto-u.ac.jp.
authors.forename: Akihito
authors.initials: A
authors.lastname: Miyoshi
authors.affiliation: Graduate School of Agricultural Science, Kobe University, 657-8501 Kobe, Japan. ikeken@phoenix.kobe-u.ac.jp.
authors.forename: Kanako
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Graduate School of Agricultural Science, Kobe University, 657-8501 Kobe, Japan. ikeken@phoenix.kobe-u.ac.jp.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Ikeda
authors.affiliation: Graduate School of Agricultural Science, Kobe University, 657-8501 Kobe, Japan. mizutani@gold.kobe-u.ac.jp.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Mizutani
authors.affiliation: Graduate School of Agricultural Science, Kobe University, 657-8501 Kobe, Japan. yukihiro@kobe-u.ac.jp.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Sugimoto
mesh_terms: D004735:Energy Transfer; D018869:Heat-Shock Response; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D045331:Photosystem I Protein Complex / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism* / Q000648:ultrastructure; D014908:Triticum / Q000378:metabolism*
chemical_list: D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex