PLANT PHYSIOLOGY , Vol 115, Issue 1 151-157, Copyright © 1997 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Antenna Size Dependency of Photoinactivation of Photosystem II in Light-Acclimated Pea Leaves
Y. Park II, W. S. Chow and J. M. Anderson
Photobioenergetics Group, Research School of Biological Sciences, Australian National University, G.P.O. Box 475, Canberra, ACT 2601, Australia
Utilization of absorbed light energy by photosystem (PS) II for O2
evolution depends on the light-harvesting antenna size, but the role of
antenna size in the photoinactivation of PSII seems controversial. To
address this controversy, pea (Pisum sativum L.) plants were grown in low
(50 [mu]mol m-2 s-1) or high (650 [mu]mol m-2 s-1) light. The doubled
functional antenna size of PSII in low light allows each PSII to utilize
twice as many photons at given flash light energies for O2 evolution. The
application of a target theory to depict the photon dose dependency of PSII
photoinactivation measured by repetitive-flash O2 yield and the ratio of
variable to maximal chlorophyll fluorescence indicates that
photoinactivation of PSII is probably a single-hit process in which repair
or photoprotective mechanisms are only slightly involved. Furthermore, the
exacerbation of photoinactivation of PSII with greater antenna size under
anaerobic conditions strongly indicates that photoinactivation of PSII
depends on antenna size.
