Cyclic electron flow provides acclimatory plasticity for the photosynthetic machinery under various environmental conditions and developmental stages.

Marjaana Suorsa

doi:10.3389/fpls.2015.00800

Abstract

Photosynthetic electron flow operates in two modes, linear and cyclic. In cyclic electron flow (CEF), electrons are recycled around photosystem I. As a result, a transthylakoid proton gradient (ΔpH) is generated, leading to the production of ATP without concomitant production of NADPH, thus increasing the ATP/NADPH ratio within the chloroplast. At least two routes for CEF exist: a PROTON GRADIENT REGULATION5–PGRL1–and a chloroplast NDH-like complex mediated pathway. This review focuses on recent findings concerning the characteristics of both CEF routes in higher plants, with special emphasis paid on the crucial role of CEF in under challenging environmental conditions and developmental stages.

Highlights

Marjaana Suorsa*Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland
Photosynthetic light reactions occur in four thylakoid membrane-embedded multiprotein complexes; photosystem (PS) II, cytochrome b6f (Cytb6f ), PSI and ATP synthase
This review focuses on the recent findings concerning the characteristics of both cyclic electron flow (CEF) routes, with special emphasis paid on the crucial role of CEF in higher plants under challenging environmental and developmental conditions

Summary

Marjaana Suorsa*

Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland. Reviewed by: Wah Soon Chow, The Australian National University, Australia Jean Alric, Centre National de la Recherche Scientifique, France. Photosynthetic electron flow operates in two modes, linear and cyclic. In cyclic electron flow (CEF), electrons are recycled around photosystem I. A transthylakoid proton gradient ( pH) is generated, leading to the production of ATP without concomitant production of NADPH, increasing the ATP/NADPH ratio within the chloroplast. At least two routes for CEF exist: a PROTON GRADIENT REGULATION5–PGRL1–and a chloroplast NDH-like complex mediated pathway. This review focuses on recent findings concerning the characteristics of both CEF routes in higher plants, with special emphasis paid on the crucial role of CEF in under challenging environmental conditions and developmental stages

Introduction

The Chloroplast NDH Complex

Involvement of CEF Upon Drought and Extreme Temperatures

CEF Plays an Important Role under Early Developmental Phases

Concluding Remarks