Genome-Wide Analysis of Terpene Synthase Gene Family in Mentha longifolia and Catalytic Activity Analysis of a Single Terpene Synthase

Terpenoids are a wide variety of natural products and terpene synthase (TPS) plays a key role in the biosynthesis of terpenoids. plants are rich in essential oils, whose main components are terpenoids, and their biosynthetic pathways have been basically elucidated. However, there is a lack of systematic identification and study of TPS in plants. In this work, we genome-widely identified and analyzed the gene family in , a model plant for functional genomic research in the genus . A total of 63 genes were identified in the genome sequence assembly, which could be divided into six subfamilies. The subfamily had the largest number of genes, which might be related to the abundant monoterpenoids in plants. The subfamily had 18 members and showed a significant species-specific expansion compared with other sequenced Lamiaceae plant species. The 63 genes could be mapped to nine scaffolds of the genome sequence assembly and the distribution of these genes is uneven. Tandem duplicates and fragment duplicates contributed greatly to the increase in the number of genes in . The conserved motifs (RR(X)8W, NSE/DTE, RXR, and DDXXD) were analyzed in TPSs, and significant differentiation was found between different subfamilies. Adaptive evolution analysis showed that were subjected to purifying selection after the species-specific expansion, and some amino acid residues under positive selection were identified. Furthermore, we also cloned and analyzed the catalytic activity of a single terpene synthase, , which belongs to the subfamily. could encode a limonene synthase and catalyze the biosynthesis of limonene, an important precursor of essential oils from the genus . This study provides useful information for the biosynthesis of terpenoids in the genus .