摘要Dear Editor,In plants,monoterpenes are a large family of volatiles that play essential roles in communicating with the surrounding environment,including pollinator attraction,pathogen defense,and plant-plant interactions (Sun et al.,2016).Dozens of monoterpene derivatives have been widely applied in the pharmaceutical,nutraceutical,flavor,and fragrance industries.Because of their high economic value,the biosynthesis of monoterpenes has been thoroughly studied (Degenhardt et al.,2009;Vranova et al.,2013).Typically,such biosynthesis reactions are accomplished by various monoterpene synthases,which convert the 10-carbon prenyl diphosphate (usually geranyl pyrophosphate [GPP]) into a large range of products (Tholl and Gershenzon,2015).A common carbocationic reaction mechanism for all monoterpene synthases starts with the ionization of GPP through removal of the pyrophosphate group,resulting in a carbocation intermediate that can undergo cyclization,hydride shifts,or other rearrangements (Degenhardt et al.,2009).