The SlMYC1-TOR Module Regulates Trichome Formation and Terpene Biosynthesis in Tomatoes (Solanum lycopersicum L.)

Trichomes, which are special structures on the surfaces of plants, play an important role in plant defense. Trichomes in tomatoes are composed of multiple cells that are divided into glandular and non-glandular trichomes. Glandular trichomes can secrete a diverse array of specialized metabolites and terpenes are the main types. Previous studies have shown that JA and TOR signaling are associated with trichomes, and there may be an interaction between these, but the mechanism remains unclear. In this study, JA signaling and its key transcription factor SlMYC1 were shown to regulate the transcript levels of terpene synthesis precursor-related genes (MEP/MVA pathways). SlTOR positively regulated the formation of type VI trichomes through GC-MS, qRT-PCR, and transient transgenic assays, and the synthesis and accumulation of monoterpenes and sesquiterpenes were positively regulated through the expression of key genes for terpene synthesis. Subsequently, SlTOR was the direct target of SlMYC1 by yeast one-hybrid, GUS, and transient expression assays. Collectively, this study revealed that tomato trichomes were regulated by SlTOR, and SlMYC1 mediated the growth and development of trichomes and the synthesis of terpenes by directly binding the promoter of SlTOR to activate its expression. This lays the foundation for the molecular regulatory mechanism of multicellular trichomes.