Terrestrial Plants Evolve Highly Assembled Photosystem Complexes in Adaptation to Light Shifts.

Yang-Er Chen,Shu Yuan,Feng Zhu,Ming Yuan,Wen-Juan Liu,Hao-Tian Mao,Nan Wu,Yan-Qiu Su,Zhong-Wei Zhang

doi:10.3389/fpls.2018.01811

Abstract

It has been known that PSI and PSII supercomplexes are involved in the linear and cyclic electron transfer, dynamics of light capture, and the repair cycle of PSII under environmental stresses. However, evolutions of photosystem (PS) complexes from evolutionarily divergent species are largely unknown. Here, we improved the blue native polyacrylamide gel electrophoresis (BN-PAGE) separation method and successfully separated PS complexes from all terrestrial plants. It is well known that reversible D1 protein phosphorylation is an important protective mechanism against oxidative damages to chloroplasts through the PSII photoinhibition-repair cycle. The results indicate that antibody-detectable phosphorylation of D1 protein is the latest event in the evolution of PS protein phosphorylation and occurs exclusively in seed plants. Compared to angiosperms, other terrestrial plant species presented much lower contents of PS supercomplexes. The amount of light-harvesting complexes II (LHCII) trimers was higher than that of LHCII monomers in angiosperms, whereas it was opposite in gymnosperms, pteridophytes, and bryophytes. LHCII assembly may be one of the evolutionary characteristics of vascular plants. In vivo chloroplast fluorescence measurements indicated that lower plants (bryophytes especially) showed slower changes in state transition and nonphotochemical quenching (NPQ) in response to light shifts. Therefore, the evolution of PS supercomplexes may be correlated with their acclimations to environments.

Highlights

Chloroplasts are plant cell organelles in which photosynthesis and other biosynthetic pathways occur
To further test whether our previous optimized method for thylakoid extraction is suitable for different plants, photosynthetic oxygen-evolving activities and 2,6-dichlorophenol indophenol (DCPIP) photoreduction of the thylakoid membranes were compared among 15 different plant species (Figure 2)
The results indicated that thylakoid membranes from all plants are functional and the thylakoid extraction method is still suitable for lower plants

Summary

Introduction

Chloroplasts are plant cell organelles in which photosynthesis and other biosynthetic pathways occur. There are four major multimeric protein complexes in thylakoid membranes: photosystem I (PSI), photosystem II (PSII), the cytochrome b6/f complex, and the ATP synthase (Caffarri et al, 2009; Nevo et al, 2012; Nelson and Junge, 2015). PSI-NDH (NAD(P)H dehydrogenase) and PSI-LHCII complexes were shown to be involved with NDH-dependent cyclic electron transfer-specific megacomplexes and state transition in Arabidopsis thaliana, respectively (Peng et al, 2009; Armbruster et al, 2013). It is unknown whether thylakoid membrane protein complexes in evolutionarily divergent organisms present evolutionary differences under natural conditions

Methods

Results

Conclusion