Interaction between photosynthetic electron transport and chloroplast sinks triggers protection and signalling important for plant productivity

Abstract

The photosynthetic light reactions provide energy that is consumed and stored in electron sinks, the products of photosynthesis. A balance between light reactions and electron consumption in the chloroplast is vital for plants, and is protected by several photosynthetic regulation mechanisms. Photosystem I (PSI) is particularly susceptible to photoinhibition when these factors become unbalanced, which can occur in low temperatures or in high light. In this study we used the pgr5 Arabidopsis mutant that lacks ΔpH-dependent regulation of photosynthetic electron transport as a model to study the consequences of PSI photoinhibition under high light. We found that PSI damage severely inhibits carbon fixation and starch accumulation, and attenuates enzymatic oxylipin synthesis and chloroplast regulation of nuclear gene expression after high light stress. This work shows that modifications to regulation of photosynthetic light reactions, which may be designed to improve yield in crop plants, can negatively impact metabolism and signalling, and thereby threaten plant growth and stress tolerance.This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.

Signaling interactions between mitochondria and chloroplasts in Nicotiana tabacum leaf

“…First, CET supports proton influx to the lumen and low lumen pH is important for the engagement of NPQ. Hence, particularly, under conditions where linear electron transport is being limited, as was the case here with all three inhibitors, the engagement of NPQ is dependent upon CET (Munekage et al , Miyake et al , Nishikawa et al , Shikanai , Gollan et al ). While MYXO (and OLIGO) treatment greatly increased NPQ, this did not occur with AA (Fig.…”

“…E). Several previous studies have suggested the acceptor‐side limitation of PSI as a source of chloroplast retrograde signals (Piippo et al , Bräutigam et al , Foyer et al , Pfalz et al , Gollan et al , , Bode et al ).…”

Consequences of photosystem‐I damage and repair on photosynthesis and carbon use in Arabidopsis thaliana

“…It has been postulated that in PSI photoinhibition conditions, molecular oxygen functions as an electron acceptor from PSI, leading to the generation of reactive oxygen species (ROS), which can react with FeS centres at PSI and lead to the inhibition of electron transport activity (reviewed in Sonoike, ). PSI photoinhibition can occur at low temperatures (Havaux and Davaud, ; Terashima et al ., ; Tjus et al ., ), but can also occur under fluctuating light conditions (Suorsa et al ., ; Kono et al ., ; Tikkanen and Grebe, ) as well as under high light conditions (Tiwari et al ., ; Gollan et al ., ).…”

Regulation of cyclic electron flow by chloroplast NADPH‐dependent thioredoxin system

“…Regularly occurring light variations induce long‐term acclimatory changes in the photosynthetic machinery via signaling mechanisms, while temporary fluctuation of light within a day transiently activates short‐term regulatory mechanisms (Armbruster et al., ; Bailey, Walters, Jansson, & Horton, ; Grieco, Tikkanen, Paakkarinen, Kangasjärvi, & Aro, ; Kono & Terashima, ). The short‐term mechanisms include nonphotochemical quenching (NPQ), photosynthetic control of electron flow between PSII and PSI, state transitions (ST), cyclic electron flow (CEF), and activation of photosynthetic enzymes both in light and carbon fixation (CBC) reactions (Balsera, Uberegui, Schürmann, & Buchanan, ; Demmig‐Adams, Cohu, Muller, & Adams, ; Gollan, Lima‐Melo, Tiwari, Tikkanen, & Aro, ; Tikkanen & Aro, ; Yamori, Makino, & Shikanai, ).…”