Metabolomic variability of four macroalgal species of the genus <i>Lobophora</i> using diverse approaches

International audience13 14 Among comparative metabolomic studies used in marine sciences, only few of them are dedicated to macroalgae 15 despite their ecological importance in marine ecosystems. Therefore, experimental data are needed to assess the 16 scopes and limitations of different metabolomic techniques applied to macroalgal models. Species of the genus 17 Lobophora belong to marine brown algae (Family: Dictyotaceae) and are widely distributed, especially in 18 tropical coral reefs. The species richness of this genus has only been unveiled recently and it includes species of 19 diverse morphologies and habitats, with some species interacting with corals. This study aims to assess the 20 potential of different metabolomic fingerprinting approaches in the discrimination of four well known 21 Lobophora species (L. rosacea, L. sonderii, L. obscura and L. monticola). These species present distinct 22 morphologies and are found in various habitats in the New Caledonian lagoon (South-Western Pacific).We 23 compared and combined different untargeted metabolomic techniques: liquid chromatography-mass 24 spectrometry (LC-MS), nuclear magnetic resonance (1 H-NMR) and gas chromatography (GC-MS). 25 Metabolomic separations were observed between each Lobophora species, with significant differences according 26 to the techniques used. LC-MS was the best approach for metabotype distinction but a combination of 27 approaches was also useful and allowed identification of chemomarkers for some species. These comparisons 28 provide important data on the use of metabolomic approaches in the Lobophora genus and will pave the way for 29 further studies on the sources of metabolomic variations for this ecologically important macroalgae. 30 3