Genome sequencing of four culinary herbs reveals terpenoid genes underlying chemodiversity in the Nepetoideae

Species within the mint family, Lamiaceae, are widely used for their culinary, cultural, and medicinal properties due to production of a wide variety of specialized metabolites, especially terpenoids. To further our understanding of genome diversity in the Lamiaceae and to provide a resource for mining biochemical pathways, we generated high-quality genome assemblies of four economically important culinary herbs, namely, sweet basil (Ocimum basilicum L.), sweet marjoram (Origanum majorana L.), oregano (Origanum vulgare L.), and rosemary (Rosmarinus officinalis L.), and characterized their terpenoid diversity through metabolite profiling and genomic analyses. A total 25 monoterpenes and 11 sesquiterpenes were identified in leaf tissue from the 4 species. Genes encoding enzymes responsible for the biosynthesis of precursors for mono- and sesqui-terpene synthases were identified in all four species. Across all 4 species, a total of 235 terpene synthases were identified, ranging from 27 in O. majorana to 137 in the tetraploid O. basilicum. This study provides valuable resources for further investigation of the genetic basis of chemodiversity in these important culinary herbs.