The chlorophyll a fluorescence induction pattern in chloroplasts upon repetitive single turnover excitations: accumulation and function of QB-nonreducing centers.
The increase of chlorophyll fluorescence yield in chloroplasts in a 12.5 Hz train of saturating single turnover flashes and the kinetics of fluorescence yield decay after the last flash have been analyzed. The approximate twofold increase in Fm relative to Fo, reached after 30-40 flashes, is associated with a proportional change in the slow (1-20 s) component of the multiphasic decay. This component reflects the accumulation of a sizeable fraction of QB-nonreducing centers. It is hypothesized that the generation of these centers occurs in association with proton transport across the thylakoid membrane. The data are quantitatively consistent with a model in which the fluorescence quenching of QB-nonreducing centers is reversibly released after second excitation and electron trapping on the acceptor side of Photosystem II.
Department of Plant Physiology, Wageningen University and Research, Wageningen, NL, USA. wim.vredenberg@wur.nl
Wim
W
Vredenberg
Vojtech
V
Kasalicky
Milan
M
Durchan
Ondrej
O
Prasil
D002734:Chlorophyll / Q000737:chemistry* / Q000378:metabolism*; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000737:chemistry* / Q000378:metabolism*; D010084:Oxidation-Reduction; D018532:Pisum sativum / Q000737:chemistry / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D045322:Photosynthetic Reaction Center Complex Proteins; D002734:Chlorophyll; D000077194:Chlorophyll A