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Herbivore‐induced plant volatiles (HIPVs) are critical compounds that directly or indirectly regulate the tritrophic interactions among herbivores, natural enemies and plants. The synthesis and release of HIPVs are regulated by many biotic and abiotic factors. However, the mechanism by which multiple factors synergistically affect HIPVs release remains unclear. Tea plant (Camellia sinensis) is the object of this study because of its rich and varied volatile metabolites. In this study, benzyl nitrile was released from herbivore‐attacked tea plants more in the daytime than at night, which was consistent with the feeding behaviour of tea geometrid (Ectropis grisescens Warren) larvae. The Y‐tube olfactometer assay and insect resistance analysis revealed that benzyl nitrile can repel tea geometrid larvae and inhibit their growth. On the basis of enzyme activities in transiently transformed Nicotiana benthamiana plants, CsCYP79 was identified as a crucial regulator in the benzyl nitrile biosynthetic pathway. Light signalling‐related transcription factor CsPIF1‐like and the jasmonic acid (JA) signalling‐related transcription factor CsMYC2 serve as the activator of CsCYP79 under light and damage conditions. Our study revealed that light (abiotic factor) and herbivore‐induced damage (biotic stress) synergistically regulate the synthesis and release of benzyl nitrile to protect plants from diurnal herbivorous tea geometrid larvae. Summary statement: Tea geometrid‐induced volatile benzyl nitrile (BN) emission has a diurnal pattern, which is consistent with the feeding of tea geometrids. Light and damage induce the emission of BN and the CsCYP79 expression which is promote by the CsMYC2 and CsPIFs‐like. [ABSTRACT FROM AUTHOR]

Jasmonic acid (JA) is reportedly involved in the interaction between insects and the vegetative parts of horticultural crops; less attention has, however, been paid to its involvement in the interaction between insects and the floral parts of horticultural crops. Previously, we investigated the allene oxide synthase 2 (AOS2) gene that was found to be the only JA synthesis gene upregulated in tea (Camellia sinensis) flowers exposed to insect (Thrips hawaiiensis (Morgan)) attacks. In our present study, transient expression analysis in Nicotiana benthamiana plants confirmed that CsAOS2 functioned in JA synthesis and was located in the chloroplast membrane. In contrast to tea leaves, the metabolite profiles of tea flowers were not significantly affected by 10 h JA (2.5 mM) treatment as determined using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry, and gas chromatography-mass spectrometry. Moreover, JA treatment did not significantly influence ethylene formation in tea flowers. These results suggest that JA in tea flowers may have different functions from JA in tea leaves and other flowers. [ABSTRACT FROM AUTHOR]