BIOEPOXY

Epoxy fatty acids can be used as precursors (synthons) in various chemical syntheses. Some of them have demonstrated antifungal activities. Their biosynthesis is however poorly known in plants, which hampers their production and biotechnological use. The aim of this project is to identify and characterize enzymes involved in the metabolism of epoxy fatty acids in plants and use this knowledge to boost the production of epoxy fatty acids in the epidermal cuticle, the « skin » of most aerial organs. The cuticle constitutes not only the first physical barriers encountered by many phytopathogens but also a major determinant of resistance to water losses. The overall goal is thus to investigate the production of epoxy fatty acids on plant aerial surfaces as a mean to improve the resistance of plants to pathogens while preserving or improving their water barrier function. Preliminary results of the two partners of the project have allowed to identify in the model plant Arabidopsis thaliana a cytochrome P450 responsible for the synthesis of epoxy fatty acids contained in the structural polymer of the cuticle (cutin polymer). In order to identify other enzymes of the cutin synthesis pathway and gain insights into the synthesis, trafficking and conversion of epoxy fatty acids, we propose to combine approaches based on transcriptomics, candidate genes and the isolation of Arabidopsis cutin mutants (domain of expertise of partner 1) and the detailed characterization of fatty acid-metabolizing P450 activities using yeast expression (domain of expertise of partner 2). Knowledge gained from these two complementary approaches will be used to select enzymes of epoxy fatty acid metabolism, overexpress them in Arabidopsis and generate transgenic plants with high amount of epoxy fatty acids in the protective cuticle layer, which could then be tested for resistance to pathogens and water losses. Previous results obtained by partner 1 and partner 2 showing the existence of a synergy between enzymes of the cutin biosynthesis pathway and the possibility to use it to produce new hydroxyl fatty acid in cutin (2007, PNAS 104:18339; 2009, PNAS 106:22008) suggest strongly that this strategy is likely to be also successful for epoxy fatty acids and is worth investigating.