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Stress oxydant, signalisation redox et chromatine

Plants are sessile organisms that have to adapt to their ever-changing environment. It is therefore essential for them to develop strategies to be able to respond rapidly and flexibly for their adaptation and survival. Numerous studies that date back three decades have established that oxidative stress and related redox signaling are important factors in plant responses to the environment, particularly stress. Thus, increased production of oxidizing molecules such as reactive oxygen species (ROS), decreased activity of ROS-metabolizing pathways, or both, can mediate a wide range of cellular responses to stress. These are manifest at the phenotypic level by such responses as modified and development involving processes such as cell death. They can also be observed as changes in the plant transcriptome, proteome, and metabolome.

The accumulation of ROS is determined by their rates of production and their rates of removal by the antioxidative system, a complex network involving several hundred genes. As well as determining the extent of ROS accumulation, certain antioxidant enzymes may be involved in coupling enhanced rates of ROS removal to oxidative signaling, analogous to processes described in other organisms such as yeast. More generally, redox signaling is known to be crucial in plant responses to changes in the environment and in the regulation of metabolism. For example, thioredoxins are small redox-active proteins that are crucial in adjusting chloroplast metabolism to the prevailing light conditions. Other key components in redox metabolism and signaling are NADPH and glutathione, small molecules that largely dictate the cellular redox state. All of these factors are encoded by or associated with multiple genes involved in their oxidation or reduction in response to stress and other environmental factors.