The contribution of electron transfer after photosystem I to balancing photosynthesis

Abstract

Light excitation at photosystem II and photosystem I drives assimilation and biosynthesis. This process is inherently dangerous, and a limitation in electron acceptors can result in damage by free radicals to photosystem II, and in extreme cases to photosystem I. This chapter deals with how regulation of electron transport events that occur after photosystem I can control the partitioning of these electrons into different metabolic pathways and sinks, and how this partitioning has the potential to influence protective quenching mechanisms. We focus on events in higher plants, and discuss the primary acceptor at photosystem I, ferredoxin, and how the diversity of ferredoxin iso-proteins can contribute to controlling electron flux into various pathways. In addition, we consider how electron flux into various alternative electron sinks and quenching pathways can be regulated to protect the plant, while maintaining competitive assimilation and biosynthesis. The integration of metabolic and reductive signals will be taken as a particular example. © 2018 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.