title: Photosynthetic proton and electron transport in wheat leaves under prolonged moderate drought stress.
abstract: In conditions of long-lasting moderate drought stress, we have studied the photoprotective responses in leaves of wheat (Triticum aestivum L., cv. Katya) related to the photosynthetic electron and proton transport. The dark-interval relaxation kinetics of electrochromic bandshift (ECS) indicated a decrease of electric and an increase of osmotic component of the proton motive force in drought stressed leaves, but neither the total proton motive force (pmf) nor the thylakoid proton conductance (gH(+)) were affected. We observed the enhanced protection against overreduction of PSI acceptor side in leaves of drought stressed plants. This was obviously achieved by the rapid buildup of transthylakoid pH gradient at relatively low light intensities, directly associated to the steep increase of NPQ and the down-regulation of linear electron transport. It was further accompanied by the steep increase of redox poise at PSII acceptor side and PSI donor side. The early responses related to thylakoid lumen acidification in drought-stressed leaves could be associated with the activity of an enhanced fraction of PSI not involved in linear electron flow, which may have led to enhanced cyclic electron pathway even in relatively low light intensities, as well as to the drought-induced decrease of IP-amplitude in fast chlorophyll fluorescence kinetics.
authors: Department of Plant Physiology, Slovak Agricultural University, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic. Electronic address: marek.zivcak@uniag.sk.
authors: Marek
authors: M
authors: Zivcak
authors: Department of Plant Physiology, Faculty of Agriculture and Biology, Warsaw Agricultural University SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland. Electronic address: hazem@kalaji.pl.
authors: Hazem M
authors: HM
authors: Kalaji
authors: Key Laboratory of Coastal Biology & Bioresources Utilization, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai 264003, PR China; Institute of Life Sciences, Qingdao University of Science & Technology, Qingdao 266042, PR China. Electronic address: shaohongbochu@126.com.
authors: Hong-Bo
authors: HB
authors: Shao
authors: Department of Plant Physiology, Slovak Agricultural University, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic. Electronic address: katarina.olsovska@uniag.sk.
authors: Katarina
authors: K
authors: Olsovska
authors: Department of Plant Physiology, Slovak Agricultural University, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic. Electronic address: marian.brestic@uniag.sk.
authors: Marian
authors: M
authors: Brestic
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism* / Q000502:physiology / Q000528:radiation effects; D011522:Protons; D013312:Stress, Physiological / Q000528:radiation effects; D013997:Time Factors; D014908:Triticum / Q000378:metabolism* / Q000502:physiology / Q000528:radiation effects
chemical_list: D045332:Photosystem II Protein Complex; D011522:Protons; D002734:Chlorophyll; C001785:chlorophyll P 700
keywords: Chlorophyll fluorescence; Cyclic electron transport; Electrochromic bandshift; Electron transport; Photosynthesis; Proton transport