Identification of Volatile Compounds and Terpene Synthase (_TPS_) Genes Reveals ZcTPS02 Involved in \(\beta\)-Ocimene Biosynthesis in _Zehyrarnthes candidia_  
Guo Wei  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. );  
ssw19990119613.com (X.S. ); [EMAIL_ADDRESS] (J.W.) Yang Xu  
College of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou 225009, China;  
[EMAIL_ADDRESS] (G.W. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (M.X. natural enemies [7; 8; 9; 10]. While the cytoplasmic mevalonate (MVA) pathway produces precursors for sesquiterpene and triterpene biosynthesis, the plastic 2-C-methyl-d-erythitol 4-phosphate (MEP) pathway generates precursors that are responsible for monoterpene and diterpene biosynthesis [11; 12]. Terpene synthases (TPSs) are pivotal enzymes in terpene biosynthesis, catalyzing the conversion of geranyl diphosphate (GPP, C\({}_{10}\)), famesyl diphosphate (FPP, C\({}_{15}\)), geranylgeranyl diphosphate (GGPP, C\({}_{20}\)), and geranylfamesyl diphosphate (GFPP, C\({}_{25}\)) into monoterpenes, sesquiterpenes, diterpenes, and sesterterpenes, respectively [13; 14; 15; 16]. While the number of _TPS_ genes in a plant's family varies among species, they share a common evolutionary origin [17; 18; 19]. Based on phylogenetic analysis, the TPS family can be divided into seven subfamilies (TPS-a to TPS-g) which possess distinct functions and taxonomic distributions. In Angiosperms, proteins encoded by TPS-a produce sesquiterpenes, whereas those encoded by TPS-b and TPS-g produce monoterpenes [18]. TPS enzymes are classified into two types: type I and type II. Type I TPS enzymes have an aspartate-rich DDxx(D,E) motif in their C-terminal domains, which is essential for binding a metal cofactor (Mg\({}^{2+}\) or Mn\({}^{2+}\)) [5].