title: Proton cellular influx as a probable mechanism of variation potential influence on photosynthesis in pea.
abstract: Electrical signals (action potential and variation potential, VP) caused by environmental stimuli are known to induce various physiological responses in plants, including changes in photosynthesis; however, their functional mechanisms remain unclear. In this study, the influence of VP on photosynthesis in pea (Pisum sativum L.) was investigated and the proton participation in this process analysed. VP, induced by local heating, inactivated photosynthesis and activated respiration, with the initiation of the photosynthetic response connected with inactivation of the photosynthetic dark stage; however, direct VP influence on the light stage was also probable. VP generation was accompanied with pH increases in apoplasts (0.17-0.30 pH unit) and decreases in cytoplasm (0.18-0.60 pH unit), which probably reflected H(+) -ATPase inactivation and H(+) influx during this electrical event. Imitation of H(+) influx using the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) induced a photosynthetic response that was similar with a VP-induced response. Experiments on chloroplast suspensions showed that decreased external pH also induced an analogous response and that its magnitude depended on the magnitude of pH change. Thus, the present results showed that proton cellular influx was the probable mechanism of VP's influence on photosynthesis in pea. Potential means of action for this influence are discussed.
authors.affiliation: Department of Biophysics, N.I. Lobachevsky State University of Nizhny Novgorod, 603950, Nizhny Novgorod, Russia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Sukhov
authors.forename: Oksana
authors.initials: O
authors.lastname: Sherstneva
authors.forename: Lyubov
authors.initials: L
authors.lastname: Surova
authors.forename: Lyubov
authors.initials: L
authors.lastname: Katicheva
authors.forename: Vladimir
authors.initials: V
authors.lastname: Vodeneev
mesh_terms: D000200:Action Potentials / Q000502:physiology* / Q000528:radiation effects; D002245:Carbon Dioxide / Q000378:metabolism; D019069:Cell Respiration / Q000502:physiology / Q000528:radiation effects; D003593:Cytoplasm / Q000378:metabolism / Q000528:radiation effects; D004558:Electric Stimulation; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008027:Light; D008954:Models, Biological; D018532:Pisum sativum / Q000166:cytology* / Q000502:physiology* / Q000528:radiation effects; D010788:Photosynthesis / Q000502:physiology* / Q000528:radiation effects; D059828:Plant Cells / Q000378:metabolism* / Q000528:radiation effects; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D011522:Protons
chemical_list: D011522:Protons; D002245:Carbon Dioxide
keywords: H+ influx; Pisum sativum; changes in pH