Transcriptional activator of part of the trichothecene biosynthesis cluster that mediates the production of the antimicrobial trichothecene harzianum A (HA) that plays a role in Botrytis cinerea antagonistic activity and plant defense priming (PubMed:21642405, PubMed:30121242). Regulates expression of both trichothecene and mevalonate pathway genes (PubMed:30121242).