# Functional Analysis of Two Terpene Synthase Genes Isolated from the Flowers of _Hosta_ 'So Sweet'
[PERSON]  
1 College of Life Sciences, Jilin Agricultural University, 2888 Xincheng Street, Changchun 130118, China; [EMAIL_ADDRESS] (B.C. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (S.Q. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Z.H. ); [EMAIL_ADDRESS] (Q.Y. ); [EMAIL_ADDRESS] (L.H. ); [EMAIL_ADDRESS] (S.L.) Zhilin Han  
1 College of Life Sciences, Jilin Agricultural University, 2888 Xincheng Street, Changchun 130118, China; [EMAIL_ADDRESS] (B.C. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (S.Q. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Z.H. ); [EMAIL_ADDRESS] (Q.Y. ); [EMAIL_ADDRESS] (L.H. ); [EMAIL_ADDRESS] (S.L.) Zhilin Han  
1 College of Life Sciences, Jilin Agricultural University, 2888 Xincheng Street, Changchun 130118, China; [EMAIL_ADDRESS] (B.C. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (S.Q. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Z.H. ); [EMAIL_ADDRESS] (Q.Y. ); [EMAIL_ADDRESS] (L.H. ); [EMAIL_ADDRESS] (S.L.) Zhilin Han  
1 College of Life Sciences, Jilin Agricultural University, 2888 Xincheng Street, Changchun 130118, China; [EMAIL_ADDRESS] (B.C. ); zhaoxue20190418@163.comdiphosphate (FPP), and geranylgeranyl diphosphate (GGPP) by preanyl-PP synthases [9]. GPP and GGPP are localized in plastids, while FPP is localized in the cytosol. The key enzymes in the biosynthetic pathways of terpenoids [10] convert the above substrates into various terpenoids with different types and structures [11; 12]. In the study of [PERSON] et al., the FaNES1 enzyme produced in _E. coli_ was capable of generating both linalool and nerolidol when supplied by in vitro enzyme activity with GPP or FPP [13]. In a recent study, three rose monoterpene synthases were functionally characterized in vitro; one had linalool synthase activity, whereas the other two had dual linalool/nerolidol synthase activity [14]. So far, numerous _TPS_ genes have been isolated from a variety of plants, and their ecological roles have been extensively studied. To our knowledge, previous studies on _TPS_ genes were mainly derived from dicotyledons, with only a few derived from monocotyledons, such as _Alstroemeria_[15], _Hedychium coronarium_[16], and _Freesia_ and _Lilium_ cultivars [17; 18]. Given the importance of floral fragrances in speciation and evolution [19; 20], more _TPS_ genes derived from monocotyledons should be studied. Plants from the genus _Hosta_ belonging to the Liliaceae family are the most well-known plants and irreplaceable resources for applied gardening and landscaping [21]. They were later classified by botanists as Asparagaceae [22]. _H. plantaginea_ (Lam.) [PERSON], the most famous species of the genus, originally from China, is widely cultivated worldwide for its leaves and flowers, along with strong adaptability to different environments, as well as a long blooming period [23; 24; 25]. _H._ 'So Sweet' originated from the hybridization of _H. plantaginea_ with _H._ 'Fragrant Bouquet' [26; 27]. These plants are also important in traditional Chinese medicine [28; 29]. The main floral components of _Hosta_ are terpen, of which monoterpene account for the majority. The main objectives of the present study were to isolate and clone the two _TPS_ genes of \(H\). 'So Sweet', and to functionally express and characterize the recombinant terpene synthases using in vitro systems. The expression pattern of the _TPS_ involved in the formation and emission of terpenoids in different flower development stages was also elucidated. This research is expected to lay the foundation for the study of _Hosta plantaginea_ terpene synthase genes. We hope that these results can provide new insight into terpene biosynthesis in monocotyledons.