Plant are sessile organisms and thus permanently need to modulate their growth in order to optimize their exposure to light or access to nutrients. They also need to efficiently react to the pathogenic pressure. In agriculture in particular, plant growth, adaptation and resistance is a major challenge as they directly impact the yield and the quality of the output food. Better understanding the fine regulation leading to plant fitness is thus an important undertaking with huge implication in real-life economy.
Plant growth regulators, such as phytohormones, are key factors for communication between parts of the plant, allowing a coordinated response of the whole plant to environmental challenges. These phytohormones are produced by specific biosynthetic pathways involving a cascade of enzymatic reactions. Currently, only a limited number of compounds have been characterized as plant growth regulators. They usually have drastic effects on plant development and have, for most of them, been known for many years. However, beside these players, recent works show that other signaling compounds with more subtle effects are also necessary for normal plant growth. The chemical natures of these compounds are yet unknown. In this project, we propose to study biosynthesis and action of overlooked plant hormones and signaling pathways using a reverse genetic approach in the model plant Arabidopsis thaliana (mouse-ear cress). In particular, we are focusing on genes coding for oxygenase enzymes belonging to the cytochrome P450 (P450) family. The P450 family plays a pivotal role in the known phytohormone biosynthesis or degradation, as all of their biosynthetic pathways, except one, require at least one P450 action to form a bioactive compound.
Our main objectives in this project is (1) to select candidate genes and test their implication on plant development as a putative actor in phytohormone biosynthesis, (2) identify the chemical compounds that are being produced by the P450s of interest and more generally (3) to apprehend how the putative signaling pathways regulates plant growth.
