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UBC Theses and Dissertations

Raman microspectroscopy in the analysis of plant cuticular membranes Okuda Andersen, Kadek


The outside of plants, including fruit, are covered by a cuticular membrane (CM). This membrane serves as protection from environmental factors. The basic composition of the CM is well understood, however, there are always variations among different species. The CM consists of a cutin matrix, which is the structural component, and cuticular waxes. The study of the CM for both structural and compositional features has been accomplished for a variety of species. The instrumentation methods used to complete these analyses have been mostly destructive and at most been able to provide spatial distribution information along the vertical axis. Raman microspectroscopy has been used previously to quantify and map triterpenoid concentrations in Prunus laurocerasus leaf CMs. This data showed transverse variations in concentration across the CM. The goal of the current work is to explore the viability of using Raman microspectroscopy to analyze other species and classes of compounds. Initially, alkylresorcinols in rye leaf waxes, artificial wax mixtures, and rye leaf CMs were examined. Using the current instrumentation it was not possible to quantify and detect alkylresorcinols in rye CMs, but it may become a viable option in the future. Based on the previous work with triterpenoids, this class of compounds was attempted next. Triterpenoids in tomato CMs were investigated resulting in the discovery that, while triterpenoids are not detectable in the tomato CM due to the presence of polysaccharides, lycopene can be detected. It was found that it is present in the remains of the epidermal cells after digestion of the cell walls (epidermal remnants), but not in the CM itself. The analysis of other species for triterpenoids was attempted including the leaves of Rosa canina, Ligustum vulgare, Kalanchoe daigremontiana, and the fruit of the Prunus avium and Prunus laurocerasus. While quantification of triterpenoids was not successful, a lot was learned about the variables which go into a successful Raman analysis of triterpenoids in plant CMs. These variables include the relative amount of triterpenoids to wax and wax to CM, along with the wax coverage (µg/cm²). These results will aid in future attempts at Raman analysis of triterpenoids in CMs.

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