Redox signal transduction in plant metabolism

Abstract

The advent of oxygenic photosynthesis was probably the second major event in the history of life on our planet, after the inception of life itself. The ability to use staples such as water and light as energy sources for the assimilation of carbon unleashed the potential of primary producers. At the same time, oxygen released as a by-product of the photosynthetic process became an effective electron acceptor for respiration. However, organisms that perform this particular type of reaction play, literally, with fire. Molecular oxygen is particularly prone to yield reduced and highly unstable reactive oxygen species (ROS), which avidly react with the electron-rich organic molecules. Oxygen builds up in the light, precisely at the same time as light-excited photosystems and transport chains handle a rich pool of free electrons. Whenever the abundance of suitable acceptors fails to match the rate of production, several mechanisms tend to transfer these electrons directly to oxygen.