Development and use of a reverse transcription-PCR assay to study expression of Tri5 by Fusarium species in vitro and in planta

The Tri5 gene encodes trichodiene synthase, which catalyzes the first react ion in the trichothecene biosynthetic pathway. In vitro, a direct relations hip was observed between Tri5 expression and the increase in deoxunivalenol production over time. We developed a reverse transcription (RT)-PCR assay to quantify Tri5 gene expression in trichothecene-producing strains of Fusa rium species. We observed an increase in Tri5 expression following treatmen t of Fusarium culmorum with fungicides, and we also observed an inverse rel ationship between Tri5 expression and biomass, as measured by beta-D-glucur onidase activity, during colonization of wheat (cv. Avalon) seedlings by F. culmorum. RT-PCR analysis also showed that for ears of wheat cv. Avalon in oculated with F. culmorum, there were different levels of Tri5 expression i n grain and chaff at later growth stages. We used the Tri5-specific primers to develop a PCR assay to detect trichothecene-producing Fusarium species in infected plant material.