Bioscience and Biotechnology Institute of Aix-Marseille
Chloroplasts are essential organelles that are the site of photosynthesis in green plants and algae. By capturing sunlight photosynthesis is the primary source of energy for the whole biosphere. Chloroplasts are at the heart of plant energy metabolism and are particularly sensitive to changes in the environment (such as light intensity) and the specific nutrient requirements of the plant. We want to find out how chloroplasts are involved in sensing environmental stress, and how they process and relay this information to the surrounding cytosol and the nucleus to mediate stress adaptationr.
Plants perceive light in the chloroplasts and also in the cytosol by photoreceptor proteins such as the phytochromes. We have shown that changes in light intensity leads to a translational response in the cytosol that affects the accumulation of nuclear-encoded chloroplast proteins such as the ELIPs and LHCs. We are currently investigating these and other posttranscriptional responses that follow changes in light intensity and quality .
Most environmental constraints lead to a situation where light energy is absorbed in excess, hence resulting in the overproduction of reactive oxygen species (ROS) inside the chloroplast. ROS originating from the chloroplast in response to high light and abiotic stress have been shown to activate specific nuclear genes. A genetic screen aimed at identifying signaling components that regulate ROS-responsive nuclear genes in
Arabidopsis thaliana, has revealed the central role of the plant topoisomerase VI (Topo VI) as a key regulator in the plant response to adverse environmental conditions (Baruah et al, 2009; Šimková et al., 2012). Our current research is aimed at elucidating the molecular mechanisms by which Topo VI and other associated chromatin factors regulate ROS-responsive gene expression changes in response to abiotic stresses of chloroplastic origin. Knowing that the production of ROS is a common feature of most abiotic stresses, results from the study of this model system may disclose widely-spread molecular mechanisms of the plant response and adaptation to adverse environmental conditions.
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.