Master's Student Cornell University Ithaca, New York
Body of Abstract: Resin glycosides (RGs) are a class of plant natural products commonly found in Convolvulaceae family species. Structurally, they are acylsugar like compounds and have diverse pharmacological and agrochemical bioactivities. RGs possess diverse structures, consisting of oligosaccharide cores, hydroxyacyl chains, and aliphatic and aromatic acyl chains. Liquid chromatography mass spectrometry analysis revealed numerous RGs in leaves and roots, exhibiting significant diversification at organ, species, and genus levels. Structural variations include the length and types of sugars in the oligosaccharide core, esterified acyl groups, long-chain fatty acids (C14-C18), and the site of macrolactone formation. Using these fundamental properties, we computationally identified hundreds of RG structures across thirty species of the Convolvulaceae family from untargeted liquid chromatography mass spectrometry data. We selected two species with divergent RG profiles and performed RNA-seq from their roots and leaves. Differential expression analysis led to identification of multiple BAHD acyltransferase candidates for RG acylation on the sugar core. Heterologous expression and in vitro enzyme assays of these candidates identified ItBAHD5 performing acylation of RG core with butyryl CoA. For functional validation of candidate genes in plants, we attempted to perform Virus Induced Gene Silencing (VIGS) in Ipomoea plants but noticed dampened VIGS phenotypes, implying that Ipomoea plants may have antiviral action that limits viral speed throughout the leaf. To pursue this direction, we tested the antiviral efficacy of Ipomoea extract containing RGs in Nicotiana benthamiana against turnip mosaic virus. Surprisingly, we observed that spraying Ipomoea extracts significantly lowered viral spread in Nicotiana plants. Further research on the molecular mechanisms underlying the biosynthesis of RGs and the identification of their target proteins and pathways can unlock their potential as therapeutic agents. Our research suggests that the exploration of RGs from natural sources holds promise for drug discovery and the development of new pharmaceutical interventions.