Herbivore‐induced plant volatiles play important ecological roles in defense against stresses. However, if and which volatile(s) are involved in the plant–plant communication in response to herbivorous insects in tea plants remains unknown. Here, plant–plant communication experiments confirm that volatiles emitted from insects‐attacked tea plants can trigger plant resistance and reduce the risk of herbivore damage by inducing jasmonic acid (JA) accumulation in neighboring plants. The emission of six compounds was significantly induced by geometrid Ectropis obliqua, one of the most common pests of the tea plant in China. Among them, (E)‐4,8‐dimethyl‐1,3,7‐nonatriene (DMNT) could induce the accumulation of JA and thus promotes the resistance of neighboring intact plants to herbivorous insects. CsCYP82D47 was identified for the first time as a P450 enzyme, which catalyzes the final step in the biosynthesis of DMNT from (E)‐nerolidol. Down‐regulation of CsCYP82D47 in tea plants resulted in a reduced accumulation of DMNT and significantly reduced the release of DMNT in response to the feeding of herbivorous insects. The first evidence for plant–plant communication in response to herbivores in tea plants will help to understand how plants respond to volatile cues in response to herbivores and provide new insight into the role(s) of DMNT in tea plants.

Herbivore-induced plant volatiles prime neighbouring plants to respond more strongly to subsequent attacks. However, the key volatiles that trigger this state and their priming mechanisms remain largely unknown. The tea geometrid Ectropis obliqua is one of the most devastating leaf-feeding pests of tea plants. Here, plant-plant communication experiments demonstrated that volatiles emitted from tea plants infested by E. obliqua larvae triggered neighbouring plants to release volatiles that repel E. obliqua adult, especially mated females. Volatile analyses revealed that the quantity of eight volatiles increased dramatically when plants were exposed to volatiles emitted by infested tea plants, including (Z)-3-hexenol, linalool, α-farnesene, β-Ocimene and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT). The results of behavioural bioassays demonstrated that β-Ocimene strongly repelled mated E. obliqua females. Individual volatile compound exposure experiments revealed that (Z)-3-hexenol, linalool, α-farnesene and DMNT triggered the emission of β-Ocimene from tea plants. Chemical inhibition experiments demonstrated that the emission of β-Ocimene induced by (Z)-3-hexenol, linalool, α-farnesene and DMNT were dependent on Ca 2+ and JA signalling. These findings help us to understand how E. obliqua moths respond to volatiles emitted from tea plants and provide new insight into volatile-mediated plant-plant interactions. They have potential significance for the development of novel insect and pest control strategies in crops. K E Y W O R D S calcium (Ca 2+ ), HIPVs, JA, mated moth, MPK signalling, tea plant 1 | INTRODUCTION As sedentary organisms, plants are under constant threat of attack from herbivores and pathogens. Throughout development, plants must adapt to their surroundings and respond to diverse environmental stimuli in ways that influence their interactions with other organisms. Thus, plants have evolved a broad range of surprisingly sophisticated mechanisms that allow them to deal with biotic and abiotic stressors (Conrath, Tingting Jing and Xiaona Qian contributed equally to this work.

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Xinyang Maojian (XYMJ) green tea is a famous high-grade Chinese green tea, but the key odorants contributing to its aroma have been poorly understood. In this study, solid-phase microextraction and solvent-assisted flavor evaporation were used for sample preparation, and gas chromatography–mass spectrometry (GC–MS) and gas chromatography–olfactometry (GC–O) were used for both qualitative and quantitative analysis. A total of 50 volatile compounds of five chemical classes were identified in XYMJ tea infusion. Among them, nine odorants including nonanal, β-ionone, octanal, E-nerolidol, linalool, cis-3-hexenyl hexanoate, geraniol, decanal, and β-cyclocitral were identified as key odorants of XYMJ based on GC–O, odor activity values, and aroma combination experiments. Changes in the content of these aroma-active compounds during the manufacturing process of XYMJ (fresh leaves, fixing, rolling, shaping, and drying) were also determined. Most aroma-active compounds decreased after the fixation process, with the exception of cis-3-hexenyl hexanoate. This is the first study to investigate the key odorants in XYMJ using the sensomics approach. The findings of this study provide novel information on the aroma quality of XYMJ.

Uridine-diphosphate dependent glycosyltransferases catalyse the glycosylation of small molecules and play an important role in maintaining cell homeostasis and regulating plant development. Glycosyltransferases are widely distributed, but their biological roles in regulating plant growth and development are largely unknown. In this study, we identified a UDP-glycosyltransferase CsUGT85A53 from Camellia sinensis, whose expression is strongly induced by various abiotic stress factors and its protein product distributed in both cytoplasm and nucleus. Ectopically over-expression of CsUGT85A53 in Arabidopsis resulted in an early flowering phenotype under both long-day and short-day conditions. The transcript accumulation of the flowering repressor genes FLC and ABI5, an activator of FLC in ABA-regulated flowering signaling, are all significantly repressed in transgenic Arabidopsis compared with wild-type plants. The decreased expression level of FLC gene might be associated with its increased DNA methylation level in CsUGT85A53-OE plants. Biochemical analyses show that CsUGT85A53 could glucosylate ABA to form inactive ABA-glycoside in vitro and in planta. Over-expression of CsUGT85A53 in Arabidopsis resulted in a decreased level of free ABA and increased level of ABA-glucoside. The early flowering phenotype in the CsUGT85A53-OE transgenic lines were restored due to ABA application. Further, CsUGT85A53 overexpressed plants displayed ABA-insensitive phenotype with higher germination rates compared with control in the presence of lower concentrations of exogenous ABA. Our findings revealed the first UGT in tea plants catalyzing ABA glucosylation and enhancing flowering transition as a positive regulator.