Evolution and diversity of plant metabolism

Emergence of the phenolic metabolism was a critical step in plant transition from water to land, and the subsequent colonization of terrestrial habitats. It provides plants with antioxidant and UV-absorbing molecules, and precursors of structural biopolymers (e.g. lignin), thus promoting the adaptation to terrestrial conditions. We investigate the evolutionary mechanisms that led to the emergence and diversification of the phenolic metabolism in land plants, and the related physiological and metabolic functions. To reach our scientific goals, we employ a unique set of model plants, including Arabidopsis thaliana (dicot), Brachypodium distachyon (monocot), Physcomitrella patens (moss) and Marchantia polymorpha (liverwort). We also implement a metabolic engineering approach, aimed at the production of phenolic antioxidants in moss.

During evolution, biosynthetic pathways seem to organize in dynamic and transient protein complexes, called metabolons. This supramolecular organization acts as another layer of cellular compartmentation and might be another level of metabolism regulation. However, the mechanism of their formations and their impacts on the metabolism are usually not taken in consideration. We study more in depth the modalities of the metabolon formation, their composition and their organization, as well as their importance in the regulation and on the plasticity of the plant specialized metabolism. For this purpose, we use the model plant P. patens and the phenylpropanoid biosynthetic pathway. Keywords: Metabolon, Phenylpropanoid metabolism, Metabolic plasticity, Physcomitrella Patens (moss), Imaging

Cutin and suberin are barriers that protect plants against different stresses like drought, pathogens, UV. They also represent a reservoir of fatty acids derivatives exhibiting diverse biological properties. Our work aims at understanding the setting of these structures constituted of poly-hydroxylated or epoxidized fatty acids linked together in a tridimensional network. Using biochemical and reverse genetic approaches, we are involved in the characterization of cytochrome P450s and epoxide hydrolases responsible for these oxidized fatty acids formation. Models: Arabidopsis, crops, legumes.

Interaction with insects is one of the many selection pressures thought to have sculpted plant metabolism, notably since many specialized metabolites act as repellents or attractants for insect species. Trade-offs between the defense-related and the intrinsic growth-related functions of metabolic pathways likely provide important selection pressures contributing to the diversity of specialized metabolism in plants. Using plant-insect interactions as a paradigm to the multi-functionality of metabolic pathways, the objective of this project is to understand the biochemistry and evolution of defense-related metabolic innovations inferred from comparative metabolomics studies. Current model systems within the Solanaceae include tomato and its wild relatives as well as Nicotiana species.

The oxidative metabolism of monoterpenes, sesquiterpenes and in particular monoterpenols such as linalool and geraniol generates numerous bioactive compounds, including iridoid antioxidants and drugs, aromatic cyclic linalool derivatives and plant defense compounds. We investigate the pathways leading to these metabolites, their role in the plant and the regulation of their production. Our model plants are grapevine for aroma studies, Arabidopsis thaliana and different Asteraceae species for defense compounds, iridoids and other active molecules.

Currently funded projects  ANR InteGrape, LabCom TerpFactory

Jasmonates (JAs) are a class of fatty acid-derived hormones acting in plant developmental steps, including the coordination of flower development for fertility, or the orchestration of inducible defence responses to attacks by microbes or insects.

We aim to determine when and how plants activate and inactivate distinct JAs to adapt their physiology to environmental cues. Based on our recent elucidation of two inactivation mechanisms of the key hormone JA-Isoleucine by CYP94s or amidohydrolases, we explore new metabolic steps having signaling potential in the JA pathway. The research will uncover metabolic regulatory networks and provide tools for targeted JA modification with agronomic or pharmaceutical interests. Models : Arabidopsis, rice.