two types of enzymes that mediate prenylation and cyclization reactions are identified, respectively. These newly discovered enzymes complete the last missing steps in linear/angular PC and FC biosynthesis. The acid/base-assisted epoxide ring opening mediated the chemical diversity and the formation of disfavored 6-endo-tet cyclization products further expanding our knowledge regarding the classical Baldwin’s rules. This study provides a suitable explanation for the generation of chemical diversity in plants. Further efforts to probe the specific and precise acid/base-assisted cyclization mechanisms at the protein structural level are ongoing.