On the sub-maximal yield and photo-electric stimulation of chlorophyll a fluorescence in single turnover excitations in plant cells.
A set of expressions is derived which quantifies the chlorophyll fluorescence yield in terms of rate constants of primary light reactions of PSII, the fraction of open and semi-open RCs and of the electric field sensed by the RC in the thylakoid membrane. The decay kinetics of the chlorophyll fluorescence yield after a single turnover excitation in the presence of DCMU show at least two components, one reversible within approx. 1 s and one with a dark reversion lasting more than 30 s. The latter is attributed to photochemical quenching; the fast component is interpreted to be associated at least partially with photo-electrochemical control. It will be illustrated that (i) the sub-maximal fluorescence yield in single turnover excitation is associated with semi-closure of RCs, (ii) the trapping efficiency of semi-closed centers is less than 50% of that of open centers and (iii) the fluorescence yield of antennas with semi-closed RCs has the highest sensitivity to changes in strength of photo-electric fields.
Vredenberg
Wim J
WJ
Laboratory of Plant Physiology, Wageningen University, Arboretumlaan 4, 6703 BD Wageningen, The Netherlands. wim.vredenberg@wur.nl
van Rensen
Jack J S
JJ
Rodrigues
Gustavo C
GC
D027463:Chenopodium album / Q000166:cytology* / Q000378:metabolism*; D002734:Chlorophyll / Q000737:chemistry* / Q000378:metabolism*; D000077194:Chlorophyll A; D004558:Electric Stimulation; D004560:Electricity; D005453:Fluorescence; D007700:Kinetics; D010777:Photochemistry; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism; D013050:Spectrometry, Fluorescence
D002734:Chlorophyll; D000077194:Chlorophyll A