Identification of the genome-wide TPS gene family of Cinnamomum camphora var. linaloolifera and functional validation of linalool

Background Cinnamomum camphora var. linaloolifera is known for its richness in linalool, which is an acyclic monoterpene widely used in the fragrance and flavour industries. However, limited information is available regarding the genome-wide identification and characterization of the key genes for linalool synthesis in C. camphora var. linaloolifera . Results Here, based on the whole genome data of Nan’an 1, a variety of C. camphora var. linaloolifera , a total of 46 CcTPS genes were identified and were classified into five subfamilies, among which TPS-b (28 members) and TPS-g (four members) clustered closely together. Functional annotation results indicated that all members of the TPS-b and TPS-g groups were associated with the synthesis of monoterpenes. Multiple sequence alignment analysis results showed that the RRX8W domain, which is mainly involved in cyclic isomerization, is relatively conserved in TPS-b and completely lost in TPS-g, suggesting that genes in the TPS-g subfamily are involved in the biosynthesis of acyclic monoterpenes. Expression analysis revealed that the expression levels of CcTPS14 , CcTPS15 , CcTPS16 and CcTPS32 from TPS-g subfamily were higher in stems and leaves than in fruits. Further results of gene function validation confirmed that these four genes all produced linalool at levels higher than 30%. Conclusion our research found that some of the ancient members of TPS-b resulted from the loss of the RRX8W structural domain responsible for cyclic isomerization, resulting in the TPS-g subfamily, which is responsible for the biosynthesis of the acyclic monoterpene linalool. Theresults provide a basis for further exploration of linalool biosynthesis and accumulation.