ARS | Publication request: Acid and neutral trehalase activities in mutants of the corn rot fungus Fusarium verticillioides

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 26, 2012
Publication Date: N/A

Technical Abstract: Fusarium verticillioides is a fungal pathogen known to cause corn rot and other plant diseases and to contaminate grain with toxic metabolites. We are characterizing trehalose metabolism in F. verticillioides with the hope that this pathway might serve as a target for controlling Fusarium disease. Trehalose is a disaccharide that is accumulated by fungi in response to stress but is present in only trace levels in most plants. In fungi, hydrolysis of trehalose to two molecules of glucose is catalyzed by a “neutral” trehalase, which acts on endogenous trehalose, and an “acid” trehalase, which acts on extracellular trehalose. The goal of this project is to measure the activities of both trehalases in extracts of F. verticillioides deletion mutants lacking one or more enzymes involved in trehalose metabolism. In the wild-type strain, trehalase activity is significantly higher in mycelia than in spores, and is not significantly affected by a reduction in glucose content of the growth medium. As expected, deletion of both the neutral and acid trehalase genes reduces trehalase activity to undetectable levels in mycelial and spore extracts, but has negligible effects on trehalose content. In extracts from a strain that lacks the gene for neutral trehalase but retains the acid trehalase gene, we detected pH dependent trehalase activity with an optimum near pH 4, which can be attributed to acid trehalase. In contrast, we are unable to observe neutral trehalase activity at any pH in extracts of a strain in which only the acid trehalase gene has been deleted. We are currently exploring the effects of media composition, stress conditions, or treatment with validamycin A (a trehalose analog and antifungal agent) on acid trehalase activity and whether these factors might also lead to observable neutral trehalase activity.