Abstract
Trichothecenes are a family of toxic metabolites produced by multiple fungal species. All trichothecene analogs include an epoxide-containing tricyclic structure known as 12,13-epoxytrichothec-9-ene (EPT) but differ by the presence, absence and types of substituents attached to EPT. Among the 21 known genes associated with trichothecene biosynthesis, tri14 is one of only three that are universally found in all trichothecene-producing fungi. Recent studies have revealed that the tri14-encoded protein, Tri14, enhances the biosynthetic reaction that forms EPT, a reaction previously thought to occur spontaneously. In our study, we assessed the impact of tri14 deletion on the biology of Trichoderma arundinaceum, a producer of the trichothecene harzianum A (HA). The results revealed that tri14 deletion reduced HA production by 69%, an outcome that was associated with diminished antifungal activity. To our knowledge, this is the first study showing that tri14 is required for wild-type production of a trichothecene analog by a fungal organism. tri14 deletion also had moderate effects on the expression of some other trichothecene biosynthetic genes, as well as in the production of metabolites beyond HA. These results suggest that Tri14 plays a crucial role in EPT formation, leading to diverse downstream effects on the biology of T. arundinaceum.