The oxidation/reduction kinetics of the plastoquinone pool controls the appearance of the I-peak in the O-J-I-P chlorophyll fluorescence rise: effects of various electron acceptors.
Quantitative analysis of the fluorescence induction (FI) rise was used in this study to elucidate the complex effects of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) on thylakoids. Reduced TMPD molecules, responsible for the ADRY agent effect, caused an increase in the amplitude of the O-J rise. Also, only oxidized TMPD molecules were shown to have the ability to bind the Q(B) pocket of photosystem II (PSII). On the other hand, the I-P rise was slowed in proportion with the oxidized TMPD concentration, inducing the clear appearance of the I-peak. While this property was previously thought to be unique to TMPD, this study shows that some artificial electron acceptors of PSII, silicomolybdate, 2,5-dichloro-p-benzoquinone, and phenyl-p-benzoquinone, have a similar effect. These results demonstrated a major role of the oxido-reduction kinetics of the PQ-pool in the resolution of J-I and I-P phases in the FI of isolated thylakoids.
Joly
David
D
Groupe de Recherche en Biologie Végétale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada G9A 5H7.
Carpentier
Robert
R
D002734:Chlorophyll / Q000737:chemistry*; D004579:Electron Transport; D005453:Fluorescence; D007202:Indicators and Reagents / Q000737:chemistry; D007700:Kinetics; D010084:Oxidation-Reduction; D018532:Pisum sativum / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D010971:Plastoquinone / Q000737:chemistry* / Q000378:metabolism; D013772:Tetramethylphenylenediamine / Q000737:chemistry; D020524:Thylakoids / Q000737:chemistry / Q000378:metabolism
D007202:Indicators and Reagents; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D010971:Plastoquinone; D013772:Tetramethylphenylenediamine