Action potential in Chara cells intensifies spatial patterns of photosynthetic electron flow and non-photochemical quenching in parallel with inhibition of pH banding.
Characean cells exposed to illumination arrange plasma-membrane H(+) fluxes and photosynthesis in coordinated spatial patterns. The limited availability of CO(2) in alkaline bands accounts for the lower effective quantum yield of photosystem II (DeltaF/F(m)') in chloroplasts of these bands compared to acidic zones. The effect of electrically triggered action potential on the spatial distribution of photosynthetic parameters (DeltaF/F(m)' and non-photochemical quenching, NPQ) and extracellular pH was studied with fluorescence imaging and pH microelectrodes. In the resting cell at a range of light intensities, the periodic profile of extracellular pH is parallel to the profile of NPQ and antiparallel to that of DeltaF/F(m)'. After triggering the action potential, the pH banding temporarily disappeared, but in contrast, the differences in effective quantum yield and NPQ patterns became more apparent. The transient changes in pH-banding, effective quantum yield and non-photochemical quenching are discussed in relation to alterations in intracellular Ca(2+) and H(+) concentrations during and after the action potential.
Krupenina
Natalia A
NA
Lomonosov Moscow State University, Faculty of Biology, 119991, Moscow, Russia. kamzolkina-n@yandex.ru
Bulychev
Alexander A
AA
Roelfsema
M Rob G
MR
Schreiber
Ulrich
U
D000200:Action Potentials; D002462:Cell Membrane / Q000737:chemistry; D044784:Chara / Q000166:cytology* / Q000378:metabolism*; D004579:Electron Transport; D006863:Hydrogen-Ion Concentration; D010777:Photochemistry; D010788:Photosynthesis