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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Mycotoxin Prevention and Applied Microbiology Research » Research » Publications at this Location » Publication #194975
Title: GBP1, A PUTATIVE MONOMERIC G-PROTEIN, IS NEGATIVELY ASSOCIATED WITH FUMONISIN B1 PRODUCTION IN FUSARIUM VERTICILLIOIDES

Author
item SAGARAM, UMA SHANKAR - TEXAS A&M UNIVERSITY
item Butchko, Robert
item SHIM, WON-BO - TEXAS A&M UNIVERSITY

Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2006
Publication Date: 7/1/2006
Citation: Shankar, S.U., Butchko, R.A.E., Shim, W.-B. 2006. The putative monomeric G-protein GBP1 is negatively associated with fumonisin B1 production in Fusarium verticillioides. Molecular Plant Pathology.

Interpretive Summary: Fumonisin is a carcinogenic toxin produced by the fungus Fusarium verticillioides. F. verticillioides can cause ear rot of corn and can contaminate the corn with fumonisin. In an effort to reduce or eliminate fumonisin contamination from corn, we are studying the biochemistry and underlying genetics of the fungus. We know there are a number of genes in the fungus which are required for toxin production. Through a process called gene knock-out (eliminating the gene under investigation), we have been able to study and understand the roles of many of the genes involved in toxin production. However, we are still studying the genetic components that regulate (control) the genes we know are required for toxin production. In this study, we have utilized a combination of techniques to identify a new gene which may have a role in regulating toxin production when F. verticillioides causes ear rot on corn. We have determined through gene knock-out that this gene is required to keep the fumonisin genes turned off. Understanding how this gene functions to suppress toxin production may lead to novel methods of preventing fumonisin contamination of corn.

Technical Abstract: Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium verticillioides that contaminates maize. FB1 has been linked to a number of human and animal mycotoxicoses worldwide. Despite its significance, our understanding of the FB1 biosynthesis regulatory mechanisms is limited. Here we describe the F. verticillioides GBP1, a monomeric G-protein, and its role in FB1 biosynthesis. GBP1 was discovered as an expressed sequence tag (EST) up-regulated in F. verticillioides fcc1 mutant that showed reduced conidiation and no FB1 biosynthesis when grown on maize kernels. Sequence analysis showed that GBP1 encodes a putative 368-amino acid protein with similarity to DRG and Obg sub-classes of G-proteins that are involved in development and stress responses. GBP1 knockout mutant (delta gbp1) exhibited normal growth, however increased FB1 production (>58%) than the wild type when grown on corn kernels. Complementation of 'gbp1 with wild-type GBP1 gene restored FB1 production to that of wild type. Our data indicate that GBP1 is negatively associated with FB1 biosynthesis but not with conidiation in F. verticillioides. The deletion of GBP1 led to up-regulation of key FB1 biosynthetic genes, FUM1 and FUM8, suggesting that the increased FB1 production in delta gbp1 is due to over-expression of FUM genes.