Roles of trichomes in tea plant resistance against multiple abiotic and biotic stresses

Tea trichomes contribute significantly to tea flavors by providing diverse and specific flavor-determining metabolites,including catechins,caffeine,theanine,and volatiles.However,not much is known about the physiological functions of tea trichomes in tea plant adaptation to complex environments,nor the trichome development.Tea trichomes not only build up chemical defenses,but also act as the first physical barrier protecting herbivore attacks,reflecting high light and UV-B radiation,and preventing water loss.Moreover,transcriptome profiling on the tea trichomes compared with the trichome-removed leaves also showed that tea trichomes highly expressed numerous defense-related genes involved in protection from high light and UV-B radiation,cold stress,disease resistance signal transduction,anti-herbivore or anti-abiotic peptide biosynthesis,and other defense responses.Several pieces of experimental evidence supported the notes,highlighting the roles of tea trichomes in plant defenses against both abiotic and biotic stresses.The study provides fresh insights into the multiple protective functions of tea trichome for tea plant adaptation to harsh environments.The new understanding on tea trichomes could benefit the development of better breading strategy for new tea varieties with greater adaption and tolerance to changing environmental challenges.