## 1 Introduction  
Tea infusions made from _Camellia sinensis_ are among the most consumed beverages around the world. The popularity of tea as a global beverage is due to its pleasant flavor and health benefits. Terpenoids belong to the largest class of natural compounds and have a significant influence on the formation of tea aroma due to their low odor thresholds and pleasant fragrances [1]. In semi-fermented and fermented teas, linalool and linalool oxides diastereomer are present in concentrations of up to 50% of the volatiles [2] and offer different flavor characteristics. Linalool and sesquiterpene nerolidol are potent odorants of black tea [3], as they impart tea products with a creamy, floral odor and have a low threshold of perception [3]. Both linalool and nerolidol are detectable in tea floral scent [4] and accumulate as non-odorous glycosides in fresh tea leaves [5]. Apart from the odorant properties, terpenoid volatiles also act as chemical messengers or attractants for pollinators [6], deterrents of herbivore predators [7], plant-plant signals [8] and other ecological function [9]. (\(E\))-Nerolidol and its derivative 4,8-dimethylnona-1,3,7-triene (DMNT) are vital for plants in response to herbivore attack [10]. Sesquiterpene farnesene was reported as an important and conserved alarm pheromone in response to a variety of aphids species, a major pest in agriculture, which seriously occurs in tea gardens in some countries that produce a great number of merchant tea [11,12]. Some attempts have been made to use synomones and kairomones in the manipulation of natural enemies to suppress pests [13]. Interestingly, several plants succeed in keeping away aphids by synthesizing farnesene, thus indicating that farnesene can be efficiently utilized as an aphid repellent [14]. Terpenoids are biosynthesized via two pathways: the cytosolic mevalonic acid (MVA) pathway and the plastid methylerythnitol phosphate (MEP) pathway (Figure 1). Both pathways lead to the formation of the C5 compounds isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). In the MEP pathway, IPP is synthesized from pyruvate and glyceraldehyde -3-phosphate [15], while in the cytosol, IPP is derived from acetyl-CoA [16]. The C5 compounds for monoterrene synthesis are derived from the plastidic pathway. Geranyl pyrophosphate (GPP) is the precursor for monoterrepenoids, and specific enzymes involved in the biosynthesis of monoterrepenoids have been identified and characterized in various plants. Terpene synthases (TPSs) in plants are extensively studied and have been divided into seven subfamilies. The biosynthesis of terpenoids in _Camellia sinensis_ is predicted based on the knowledge of the pathways elucidated in other plants, whereas the scenarios of genes to metabolites of terpen biosynthesis pathway in tea plants remain uninvestigated and most of the TPSs in tea plants, until now, are unknown, except the recently characterized TPSs involved in the formation of (_E_)-nerolidol, linalool [17, 18], ocimene [19] and \(\alpha\)-farnesene [20]. Figure 1: Pathway associated with terpenene synthesis in _Camellia sinensis_. The following enzymes and compounds are involved in the MVA pathway: AACT, acetoacetyl-CoA thiolase; HMGS, 3-hydroxy-3-methylglutaryl- coenzyme (a synthase); HMGR, 3-hydroxy-3-methylglutaryl coenzyme (a reductase); MVK, mevalonate kinase; PMK, 5-phosphatemovalonate kinase; MDC, mevalonate-5-phosphate decarboxylase; IPP, isopentenyl pyrophosphate; IDI, isopentenyl pyrophosphate isomerase; DMAPP, dimethylallyl pyrophosphate.