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The involvement of change in excitation energy spillover from PSII to PSI during state transitions in wheat leaves

Tan Xinxing, Xu Daquan, Shen Yungang

Shanghai Institute of Plant Physiology, The Chinese Academy of Sciences. Shanghai 200032

Abstract

The red light or far red light induced changes in chlorophyll fluorescence parameters and fluorescence spectrum at low temperature were observed in wheat leaves to investigate whether the change in excitation energy distribution between the two photosystems during state transitions involves the change in excitation energy spillover from PSII to PSI.The chlorophyll fluorescence parameter, Fm/Fo, and the ratio of fluorescence yield of the two photosystems at low temperature, F685/F735,increased when leaves were exposured to lightI (far red light), while they decreased when leaves were exposured to lightII (red light). During illumination by lightI or lightII, the change in Fm/Fo attained to a maximum extent in a shorter time as compared with the change in F685/F735. In the leaves fed with NaF through its cut end, Fm/Fo and F685/F735 did not increase on exposure to lightI. The extent of decrease of Fm/Fo and F685/F735 in the leaves fed with DCMU also through the cut end of leaf was less than that in control without feeding of DCMU on exposure to lightII. Based on the results above, the following conclusions are made: a)the change in excitation energy distribution between the two photosystems during state transitions is, at least partly, related to change in excitation energy spillover from PSII to PSI; b) the change in the spillover is associated with phosphorylation of LHC II, and it is a quicker response to the inbalant light absorption of the two photosystems as compared with the change in light absorption cross-section.

Key words: State transition;Photochemical efficiency of PSⅡ;Spillover;LHCⅡphosphorylation;Chlorophyll fluorescence;Wheat

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Citing This Article：

Tan Xinxing, Xu Daquan, Shen Yungang. The involvement of change in excitation energy spillover from PSII to PSI during state transitions in wheat leaves. Acta Physiol Sin 1997; 49 (1): (in Chinese with English abstract).