High Root Temperature Blocks Both Linear and Cyclic Electron Transport in the Dark During Chilling of the Leaves of Rice Seedlings

Kensaku Suzuki, Yukimi Ohmori, Emilien Ratel
2011 Plant and Cell Physiology  
The most photosynthetically active leaves of rice seedlings were severely damaged when shoots but not roots were chilled (10 C/25 C, respectively), but no such injury was observed when the whole seedling was chilled of the 550-515 nm difference signal indicated decreased formation of a proton gradient across the thylakoid membrane and decreased zeaxanthin formation in the 10 C/25 C leaves. Our results suggest that electron transport was blocked between Q A and Q B in the dark 10 C/25 C leaves,
more » ... 10 C/25 C leaves, but without irreversible damage to the components of this system. The consequent light-dependent losses of electron transport, proton gradient formation across the thylakoids and thermal dissipation may therefore be responsible for the visible injury. Keywords: Chilling injury Electron transport PSII Rice Root temperature Thermal dissipation. Abbreviations: ÁpH, proton gradient; DCIP red , reduced form of 2,6-dichloroindophenol; DMQ, 2,5-dimethylbenzoquinone; ECS, the electrochromic pigment absorbance shift; ETR, electron transport rate; ETR I , electron transport rate in PSI; ETR II , electron transport rate in PSII; F, fluorescence measured during illumination; F m , maximum fluorescence of darkadapted leaf; F m 0 , the maximum fluorescence measured during illumination; F o , minimum fluorescence of the darkadapted leaf; F o 0 , the minimum fluorescence immediately after illumination; F P , fluorescence at the peak (P) of the fast fluorescence induction phase; F v , variable fluorescence; F v /F m , maximum quantum yield of PSII; NPQ, nonphotochemical quenching of excitation energy; P700, reaction center Chl in PSI; PAR, photosynthetically active radiation; f I , the effective photochemical quantum yield of PSI; f II , the effective photochemical quantum yield of PSII; f NA , the quantum yield of non-photochemical energy dissipation in PSI due to acceptor-side limitations; f ND , the quantum yield of non-photochemical energy dissipation in PSI due to donor-side limitations; f NO , the quantum yield of non-lightinduced non-photochemical fluorescence quenching in PSII; f NPQ , the quantum yield of light-induced nonphotochemical fluorescence quenching in PSII; P m , the maximum P700 + signal; Q A and Q B , primary and secondary quinone electron acceptors of PSII, respectively; qP, photochemical quenching in PSII; ROS, reactive oxygen species
doi:10.1093/pcp/pcr104 pmid:21803813 fatcat:vlwjzsn6vjbrvkojw4exidegoa