title: Responses of the photosynthetic electron transport system to excess light energy caused by water deficit in wild watermelon.
abstract: In plants, drought stress coupled with high levels of illumination causes not only dehydration of tissues, but also oxidative damage resulting from excess absorbed light energy. In this study, we analyzed the regulation of electron transport under drought/high-light stress conditions in wild watermelon, a xerophyte that shows strong resistance to this type of stress. Under drought/high-light conditions that completely suppressed CO(2) fixation, the linear electron flow was diminished between photosystem (PS) II and PS I, there was no photoinhibitory damage to PS II and PS I and no decrease in the abundance of the two PSs. Proteome analyses revealed changes in the abundance of protein spots representing the Rieske-type iron-sulfur protein (ISP) and I and K subunits of NAD(P)H dehydrogenase in response to drought stress. Two-dimensional electrophoresis and immunoblot analyses revealed new ISP protein spots with more acidic isoelectric points in plants under drought stress. Our findings suggest that the modified ISPs depress the linear electron transport activity under stress conditions to protect PS I from photoinhibition. The qualitative changes in photosynthetic proteins may switch the photosynthetic electron transport from normal photosynthesis mode to stress-tolerance mode.
authors: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama, Ikoma, Nara, Japan.
authors: Satoko
authors: S
authors: Sanda
authors: Kazuo
authors: K
authors: Yoshida
authors: Masayoshi
authors: M
authors: Kuwano
authors: Tadayuki
authors: T
authors: Kawamura
authors: Yuri Nakajima
authors: YN
authors: Munekage
authors: Kinya
authors: K
authors: Akashi
authors: Akiho
authors: A
authors: Yokota
mesh_terms: D000595:Amino Acid Sequence; D029773:Citrullus / Q000502:physiology* / Q000528:radiation effects*; D055864:Droughts; D004579:Electron Transport / Q000528:radiation effects; D015180:Electrophoresis, Gel, Two-Dimensional; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008027:Light; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010788:Photosynthesis / Q000502:physiology* / Q000528:radiation effects*; D018515:Plant Leaves / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D012987:Soil; D012995:Solubility / Q000528:radiation effects; D013312:Stress, Physiological / Q000528:radiation effects; D020524:Thylakoids / Q000502:physiology / Q000528:radiation effects; D014867:Water
chemical_list: D007506:Iron-Sulfur Proteins; D008565:Membrane Proteins; D010940:Plant Proteins; D012987:Soil; D014867:Water