Photosynthesis Research

, Volume 99, Issue 3, pp 173–183

Dynamics of higher plant photosystem cross-section associated with state transitions

Regular Paper

DOI: 10.1007/s11120-008-9387-x

Cite this article as:
Ruban, A.V. & Johnson, M.P. Photosynth Res (2009) 99: 173. doi:10.1007/s11120-008-9387-x

Abstract

Photosynthetic state transitions are a well-known phenomenon of short-term adaptation of the photosynthetic membrane to changes in spectral quality of light in low light environments. The principles of the monitoring and quantification of the process in higher plants are revised here. The use of the low-temperature excitation fluorescence spectroscopy for analysis of the photosystem I antenna cross-section dynamics is described. This cross section was found to increase by 20–25% exclusively due to the migration and attachment of LHCIIb complex in State 2. Analysis of the fine structure of the additional PSI cross-section spectrum revealed the 510 nm band, characteristic of Lutein 2 of LHCIIb and present only when the complex is in a trimeric state. The excitation fluorescence spectrum of the phospho-LHCII resembles the spectrum of aggregated and hence quenched LHCII. This novel observation could explain the fact that at no point in the course of the state transition high fluorescence and long lifetime components of detached trimeric LHCII have ever been observed. In the plants lacking Lhcb1 and 2 proteins and unable to perform state transitions, compensatory sustained adjustments of the photosystem I and II antennae have been revealed. Whilst the major part of the photosystem II antenna is built largely of CP26 trimers, possessing less chlorophyll b and more of the red-shifted chlorophyll a, photosystem I in these plants contains more than 20% of extra LHCI antenna enriched in chlorophyll b. Hence, both photosystems in the plants lacking state transitions have less spectrally distinct antennae, which enable to avoid energy imbalance due to the changes in the light quality. These alterations reveal remarkable plasticity of the higher plant photosynthetic antenna design providing the basis for a flexible adaptation to the light environment.

Keywords

The state transitions Cross-section Phospho-LHCII Excitation fluorescence spectrum 

Abbreviations

LHCIIb

The major light harvesting complex of photosystem II

PSI and II

Photosystems I and II

CP26

A minor antenna complex of photosystem II

PAM

Pulse amplitude modulated

NPQ

Nonphotochemical fluorescence quenching

OD

Optical density

T

Transmission

Fo and Fm

Fluorescence levels when all PSII reaction centres are open or closed, respectively

Fv

Variable fluorescence (Fv = Fm − Fo)

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.School of Biological and Chemical SciencesQueen Mary University of LondonLondonUK

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