Solanaceae specialized metabolism in a non-model plant: trichome acylinositol biosynthesis

Plants make hundreds of thousands of biologically active specialized metabolites varying widely in structure, biosynthesis and the processes that they influence. An increasing number of these compounds are documented to protect plants from harmful insects, pathogens, or herbivores, or mediate interactions with beneficial organisms including pollinators and nitrogen fixing microbes. Acylsugars - one class of protective compounds - are made in glandular trichomes of plants across the Solanaceae family. While most described acylsugars are acylsucroses, published examples also include acylsugars with hexose cores. The South American fruit crop Solanum quitoense (Naranjilla) produces acylsugars that contain a myo-inositol core. We identified an enzyme that acetylates triacylinositols, a function homologous to the last step in the Solanum lycopersicum acylsucrose biosynthetic pathway. Our analysis reveals parallels between S. lycopersicum acylsucrose and S. quitoense acylinositol biosynthesis, suggesting a common evolutionary origin.