## 1 Introduction  
_Vitis vinifera_ is an economical and useful grape vine, and its numerous varieties facilitate the making of high-quality wines. Terpenenoids, especially monoterepenoids and sesquiterpenoids, greatly contribute to characteristic varietal aroma of the grapes and wines. Based on the level of free monoterepenoids produced in the berries, [PERSON] and [PERSON] proposed that grape varieties could be generally classified into muscat varieties (up to 6 mg/L of free monoterepenoids), non-muscat aromatic varieties (between 1-4 mg/L) and neutral varieties (less than 1 mg/L) [1]. Typical monoterepanol components of aroma-rich grape varieties are linalool, geraniol, nerol, citronello and \(\alpha\)-terpineol. In particular, linalool is one of the most odour-active odorants [2, 3] and has been shown as a crucial constituent of grape berry aroma. For example, in Burgundy region, \"Chardonnay 809\" is featured \"muscat\" aroma as a result of its very high concentration of linalool, which is distinguished from \"Chardonnay 76\" specified as being neutral variety [4]. Linalool also represents the characteristic varietal aroma of non-muscat \"Riesling\" berries [5, 6]. So it is necessary to explore the mechanism of linalool accumulation during the development of grape berries. Much evidence has demonstrated that higher plants like grape produce terpenenoid precursor, isopentenyl diphosphate (IPP), through two distinct routes: cytosolic mexulonic acid (MVA) pathway and plastidial 2C-methyl-d-erythitro1 4-phosphate (MEP) pathway [7, 8]. The condensation of IPP and its allylic isomer dimethylallyl diphosphate (DMAPP) yields geranyl diphosphate (GPP), farnesyl diphosphate (FPP) and geranylgeranyl diphosphate (GGPP) under the action of GPP synthase, FPP synthase and GGPP synthase, respectively. Afterwards, these products successively convert into different kinds of terpenoids, such as monoterepenes (C10), sesquiterpenes (C15), diterpenes (C20), triterpenes (C30), carotenoids (C40), and so on [8]. In this process, terpene synthase (TPS) plays a critical role in the formation of monoterepenes and sesquiterpenes [9, 10]. According to previous reports on phylogenetic analysis of TPS amino acid sequences [11, 12, 13], TPS family is classified into seven subfamilies designated as TPS-a, TPS-b, TPS-c, TPS-d, TPS-e/f, TPS-g and TPS-h [10]. Among these, the members of TPS-g and TPS-b have been _in vitro_ demonstrated to convert GPP, FPP and GGPP into monoterepenes, sesquiterpene and diterpene, respectively [10, 13, 14, 15]. Two natural types of linalool isomers (\(3S\) and \(3R\)) exist in higher plants, while the \(3S\)-type are the predominant in grape berries [16]. The genes encoding linalool synthase, have been isolated and characterized from many angiosperms, such as _Clarkia breweri_[17], _Arabidopsis thaliana_[18], rice [19], snapdragon [15], strawberry, poplar and others [20]. According to the stereochemistry of their catalytic products, these known linalool synthases in plants are classified into two groups: \(3S\)-linalool synthase (EC 4.2.3.25) and \(3R\)-linalool synthase (EC 4.2.3.26). The former one belongs to the TPS-g subfamily, which includes nearly all the group I LIS responsible for the synthesizing \(3S\) isomer of linalool. And the latter one belongs to the TPS-b subfamily responsible for the synthesis of \(3R\)-linalool. In _Vitis vinifera_ groups, multiple terpene synthases (VvTPS) have been functionally identified [14]. The researchers have provided comprehensive annotation of the large _VvTPS_ gene family, including chromosomal localization, enzyme functions and phylogeny relevant to the overall plant _TPS_ gene family. Several genes of the TPS-g sub family from Pinot Noir and Cabernet Sauvignon have been considered to be potential 3\(S\)-linalool synthases. _In vitro_ experiments showed that VvPNLinNer1, VvPNLinNer2 and VvCSLinNer were bi-functional enzymes and they could convert not only GPP to 3\(S\)-linalool but also FPP to (\(E\))-nerolidol.