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An ancient bacterial heritage restrains photosynthesis in plants


​CNRS and AMU researchers associated with the CEA have demonstrated that an ancient signaling pathway that was inherited from bacteria affects growth and development in plants.

​The signaling pathway operates by regulating the function of the chloroplast, the site of photosynthesis in plants and algae. This​ work has the potential to lead to the development of new strategies for protecting crops from climate change and for enhancing photosynthesis to create biofuels and other valuable products.

These results are published in Plant Cell on February 25th 2016 and were highlighted as a press release in the French national press.​​

Published on 26 February 2016

In this study, researchers from the CEA, CNRS and Aix-Marseille University investigated a poorly understood plant signaling pathway that was inherited from the bacterial ancestor of the chloroplast. This signaling pathway is mediated by the molecule guanosine tetraphosphate, which is known to play an important role in the response of bacteria to stress. By using genetics to modify the amount of guanosine tetraphosphate in the chloroplast, the researchers were able to show that this molecule acts as a potent inhibitor of chloroplast function. Surprisingly, they also discovered that this bacterial signaling pathway is at the center of a dialogue between the chloroplast and the nucleus of the cell that controls the growth and development of the plant.

The guanosine tetraphosphate signaling pathway could be exploited to help optimize the photosynthetic yield and growth of plants under different conditions (for example water or nutrient deficiency) and has potential applications in agriculture, green chemistry, and enhancing the yield of biofuel extracted from algae.

Plant and algal chloroplasts originate from the endosymbiosis of an ancient photosynthetic bacterium by a eukaryotic cell (the common ancestor of animals and plants) that took place more than one billion years ago. Thanks to this extraordinary alliance the photosynthetic eukaryotes (green plants and algae) now sustain the different ecosystems of the planet.

BIAM : Biosciences and Biotechnologies Institute of Aix-Marseille
BVME : Department of Plant Biology and Environmental Microbiology
LISM : Laboratory for the Engineering of Macromolecular Systems​

Image Legend : A normal plant (top left) and a plant that over accumulates guanosine tetraphosphate (top right). The chlorophyll fluorescence image (bottom) shows a high basal response in the plant that over accumulates guanosine tetraphosphate. This is due to a malfunction in photosynthesis caused by a breakdown in communication between the chloroplast and the nucleus.

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