ARS | Publication request: Myrothecium Roridum Tri4 Encodes a Lethal Factor for Host Bacterium

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract
Publication Acceptance Date: August 2, 2006
Publication Date: August 2, 2006
Citation: Alexander, N.J., Mc Cormick, S.P. 2006. Myrothecium roridum tri4 encodes a lethal factor for host bacterium [abstract]. Phytopathology. 96:S4.

Technical Abstract: The biosynthesis of trichothecene mycotoxins in Fusarium graminearum and Myrothecium roridum involve complex biochemical pathways that share a common beginning, the cyclization of farnesyl pyrophosphate to the sesquiterpene hydrocarbon trichodiene. While most of the steps in the Fusarium pathways have been identified, there are still some questions regarding Myrothecium toxin biosynthesis. We have successfully used a transgenic system for studying the function of F. graminearum Tri4 (FgTri4) by heterologous expression of FgTri4 in F. verticillioides, which does not produce trichothecenes. Transgenic F. verticillioides, carrying FgTri4 under the control of a F. verticillioides fumonisin biosynthetic gene (FUM8) promoter, converted exogenous trichodiene to isotrichodermin showing that the FgTRI4 protein is a multifunctional monooxygenase. To determine the function of M. roridum Tri4 (MrTri4), we used the same transgenic approach but found that this construct, in one orientation, was lethal to the host bacterium. Another construct carrying a truncated MrTri4 without the F. verticillioides Fum8 promoter, was also lethal. This suggests that certain segments of MrTri4 may encode an antimicrobial peptide.