Metabolite Profiling and Transcriptome Analysis Revealed the Chemical Contributions of Tea Trichomes to Tea Flavors and Tea Plant Defenses

Tea trichomes contain special flavor-determining metabolites; however, little is known about how and why tea trichomes produce them. Integrated metabolite and transcriptome profiling on tea trichomes in comparison with that on leaves showed that trichomes contribute to tea plant defense and tea flavor and nutritional quality. These unicellular, nonglandular, and unbranched tea trichomes produce a wide array of tea characteristic metabolites, such as UV-protective flavonoids, insect-toxic caffeine, herbivore-defensive volatiles, and theanine, as evidenced by the expression of whole sets of genes involved in different metabolic pathways. Both dry and fresh trichomes contain several volatiles and flavonols that were not found or at much low levels in trichome-removed leaves, including benzoic acid derivatives, lipid oxidation derivatives, and monoterpene derivatives. Trichomes also specifically expressed many disease signaling genes and various antiherbivore or antiabiotic peptides. Trichomes are one of the domestication traits in tea plants. Tea trichomes contribute to tea plant defenses and tea flavors.