Chapter 5 - Abiotic stress and adaptation of electron transport: Regulation of the production and processing of ROS signals in chloroplasts

Abstract

Chloroplasts are photosynthetic organelles that fix carbon dioxide from the atmosphere into sugars using energy from sunlight, whilst releasing oxygen as a by-product. They are also crucial sensors for environmental change that produce a vast array of signalling molecules, perhaps the most important of which are reactive oxygen species (ROS) such as singlet oxygen, superoxide, and hydrogen peroxide. Whilst efficient regulation of the photosynthetic electron transport chain limits ROS production and hence the extent of associated redox signalling under optimal conditions, exposure to environmental stresses causes increased ROS production and accumulation. The benefits of stress induced ROS signalling and redox regulation more than offset any collateral damage that may be caused. We provide an overview of current knowledge and concepts, including recent findings concerning the regulation of photosynthetic electron transport and the fine tuning of ROS production in response to changing environmental conditions, a process that controls the signalling functions of chloroplasts.