Environmentally-Induced Oxidative Stress and Its Signaling

Several reactive oxygen species (ROS) are continuously produced in plants as byproducts of aerobic metabolism. Chloroplasts are a major site of ROS generation in plants. Many environmental changes such as light, temperature, drought, pathogens or nutrient stresses affect the efficiency of photosynthesis and result in ROS production. Over the last few years, a wide range of plant responses have been found to be triggered by ROS. Several examples of how changes in ROS concentrations are perceived and transferred into signals that change the transcription of genes have been described. Moreover, the chemical identity of a given ROS seems to affect the specificity of its biological activity, thus increasing further the complexity of ROS signaling within the plant. Although the mechanisms that control ROS signaling remain to be established more precisely, we are beginning to understand how ROS signals are integrated to finally regulate biological processes such as development, acclimation, hypersensitive reactions and programmed cell death.