title: Quantum yield of charge separation in photosystem II: functional effect of changes in the antenna size upon light acclimation.
abstract: We have studied thylakoid membranes of Arabidopsis thaliana acclimated to different light conditions and have related protein composition to excitation energy transfer and trapping kinetics in Photosystem II (PSII). In high light: the plants have reduced amounts of the antenna complexes LHCII and CP24, the overall trapping time of PSII is only ∼180 ps, and the quantum efficiency reaches a value of 91%. In low light: LHCII is upregulated, the PSII lifetime becomes ∼310 ps, and the efficiency decreases to 84%. This difference is largely caused by slower excitation energy migration to the reaction centers in low-light plants due to the LHCII trimers that are not part of the C2S2M2 supercomplex. This pool of "extra" LHCII normally transfers energy to both photosystems, whereas it transfers only to PSII upon far-red light treatment (state 1). It is shown that in high light the reduction of LHCII mainly concerns the LHCII-M trimers, while the pool of "extra" LHCII remains intact and state transitions continue to occur. The obtained values for the efficiency of PSII are compared with the values of Fv/Fm, a parameter that is widely used to indicate the PSII quantum efficiency, and the observed differences are discussed.
authors.affiliation: Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam , 1081 HV Amsterdam, The Netherlands.
authors.forename: Emilie
authors.initials: E
authors.lastname: Wientjes
authors.forename: Herbert
authors.initials: H
authors.lastname: van Amerongen
authors.forename: Roberta
authors.initials: R
authors.lastname: Croce
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D004735:Energy Transfer; D007700:Kinetics; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D020524:Thylakoids / Q000378:metabolism
chemical_list: D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D010940:Plant Proteins