Biosynthetic investigation of $\gamma$-lactones in Sextonia rubra wood using in situ TOF-SIMS MS/MS imaging to localize and characterize biosynthetic intermediates

Tingting Fu (1, 2, 3) , Emeline Houël , Nadine Amusant , David Touboul (3) , Grégory Genta-Jouve (4) , Serge Della-Negra (2) , Gregory L. Fisher (5) , Alain Brunelle (3) , Christophe Duplais

1 UP11 - Université Paris-Sud - Paris 11
2 IPNO - Institut de Physique Nucléaire d'Orsay
3 ICSN - Institut de Chimie des Substances Naturelles
4 UPD5 - Université Paris Descartes - Paris 5
5 PHI - Physical electronics

Molecular analysis by parallel tandem mass spectrometry (MS/MS) imaging contributes to the in situ characterization of biosynthetic intermediates which is crucial for deciphering the metabolic pathways in living organisms. We report the first use of TOF-SIMS MS/MS imaging for the cellular localization and characterization of biosynthetic intermediates of bioactive γ-lactones rubrynolide and rubrenolide in the Amazonian tree Sextonia rubra (Lauraceae). Five γ-lactones, including previously reported rubrynolide and rubrenolide, were isolated using a conventional approach and their structural characterization and localization at a lateral resolution of ~400 nm was later achieved using TOF-SIMS MS/MS imaging analysis. 2D/3D MS imaging at subcellular level reveals that putative biosynthetic γ-lactones intermediates are localized in the same cell types (ray parenchyma cells and oil cells) as rubrynolide and rubrenolide. Consequently, a revised metabolic pathway of rubrynolide was proposed, which involves the reaction between 2-hydroxysuccinic acid and 3-oxotetradecanoic acid, contrary to previous studies suggesting a single polyketide precursor. Our results provide insights into plant metabolite production in wood tissues and, overall, demonstrate that combining high spatial resolution TOF-SIMS imaging and MS/MS structural characterization offers new opportunities for studying molecular and cellular biochemistry in plants.

Mots clés: ion mass-spectrometry; alkene-alkyne pair; stem wood; heartwood; rubrynolide; resolution

Mots clés: rubrenolide; butanolides; constituents; metabolites

Domaines: Chimie analytique; Chemo-informatique

Tingting Fu, Emeline Houël, Nadine Amusant, David Touboul, Grégory Genta-Jouve, et al.. Biosynthetic investigation of $\gamma$-lactones in Sextonia rubra wood using in situ TOF-SIMS MS/MS imaging to localize and characterize biosynthetic intermediates. Scientific Reports, 2019, 9 (1), pp.1928. ⟨10.1038/s41598-018-37577-5⟩. ⟨hal-02066013⟩