Microbial-type terpene synthase genes occur widely in nonseed land plants, but not in seed plants

Significance Terpenoids are ubiquitous products made by land plants with diverse biological functions. Their formation in seed plants is catalyzed by typical plant terpene synthases (TPSs), a well-characterized group of enzymes. In contrast, our knowledge of terpenoid biosynthesis in nonseed plants is very limited. By systematically analyzing the transcriptomes and/or genomes of more than 1000 plant species, we report that microbial terpene synthase-like genes, which are only distantly related to typical plant TPS genes, are widely distributed in nonseed plants, but virtually absent in seed plants. The study provides insights into the evolution of TPS genes in early land plants and opens the door to investigating the diversity and functions of terpenoids in nonseed plants.