LaMYC7, a positive regulator of linalool and caryophyllene biosynthesis, confers plant resistance to Pseudomonas syringae

Linalool and caryophyllene are the main monoterpene and sesquiterpene compounds in lavender; however, the genes regulating their biosynthesis still remain many unknowns. Here, we identified LaMYC7, a positive regulator of linalool and caryophyllene biosynthesis, confers plant resistance to . was highly expressed in glandular trichomes, and overexpression could significantly increase the linalool and caryophyllene contents and reduce susceptibility to in . In addition, the linalool possessed antimicrobial activity against growth and acted dose-dependently. Further analysis demonstrated that LaMYC7 directly bound to the promoter region of , which encodes the terpene synthase (TPS) for caryophyllene biosynthesis, and that was highly expressed in glandular trichomes. Notably, the promoter contained hormone and stress-responsive regulatory elements and responded to various treatments, including ultraviolet, low temperature, salt, drought, methyl jasmonate, and infection treatments. Under these treatments, the changes in the linalool and caryophyllene contents were similar to those in transcript abundance. Based on the results, LaMYC7 could respond to infection in addition to being involved in linalool and caryophyllene biosynthesis. Thus, the MYC transcription factor gene can be used in the breeding of high-yielding linalool and caryophyllene lavender varieties with pathogen resistance.