Elucidation of the Regular Emission Mechanism of Volatile beta-Ocimene with Anti-insect Function from Tea Plants (Camellia sinensis) Exposed to Herbivore Attack

Herbivore-induced plant volatiles (HIPVs) play an important role in insect resistance. As a common HIPV in tea plants (Camellia sinensis), beta-ocimene has shown anti-insect function in other plants. However, whether beta-ocimene in tea plants also provides insect resistance, and its mechanism of synthesis and emission are unknown. In this study, beta-ocimene was confirmed to interfere with tea geometrid growth via signaling. Light was identified as the key factor controlling regular emission of beta-ocimene induced by the wounding from tea geometrids. beta-Ocimene synthase (CsBOS1) was located in plastids and catalyzed beta-ocimene formation in overexpressed tobacco. CsBOS1 expression in tea leaves attacked by tea geometrids showed a day-low and night-high variation pattern, while CsABCG expression involved in volatile emission showed the opposite pattern. These two genes might regulate the regular beta-ocimene emission from tea plants induced by tea geometrid attack. This study advances the understanding on HIPV emission and signaling in tea plants.