EVOLUTION OF THE CHEMICAL COMPOSITION OF GINKGO BILOBA EXTERNAL AND INTERNAL LEAF LIPIDS THROUGH SENESCENCE AND LITTER FORMATION

Abstract

External and internal lipids were analysed in fresh, senescent and litter leaves of Ginkgo biloba to derive qualitative and quantitative information on the changes that occur during the very early stages of diagenesis, and to identify potential biomarkers of the only living Ginkgoale. Analysis of fresh leaves led to the identification of additional compounds, including several series of phenolic constituents, and showed differences between the external and internal lipids (absence/presence of some components, relative abundances and distributions of some series). Pronounced differences concerned with the evolution of content (as wt.% of whole leaves) were observed between the internal lipids (regular decrease from fresh to senescent and to litter leaves) and the external lipids (no significant changes in content). Molecular studies showed variations in the relative abundances and distributions of most constituents of G. biloba leaf lipids which reflect different degrees of stability during the first stages of diagenesis. It also appeared that (i) the phenolic components and the co-occurrence of α-tocopherol and nonacosan-10-ol could be useful biomarkers of G. biloba, and (ii) most of the internal lipids continue to be exported to the leaf surface where they are further degraded during senescence and litter formation.