Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/21/2017
Publication Date: N/A
Technical Abstract: Due to the health and economic costs of mycotoxins produced by Fusarium species, there is a compelling need for improved understanding of these fungi, from across diverse perspectives and disciplinary approaches. Current research at the USDA ARS Mycotoxin Prevention unit addresses Fusarium mycotoxins via research in chemistry, genomics and phylogenetics, fungal biology, plant-pathogen-environment interactions, and the phytobiome. Chemistry: We are active in screening isolates for toxin production to define the phylogenetic boundaries of trichothecene production, and in the identification of biotransformations that may limit the toxicity of trichothecenes. Acetylation of the C-3 oxygen helps protect Fusarium from the toxic effects of the trichothecenes during biosynthesis but toxins are deacetylated in infected plant tissue. Glycosyltransferases in plants can convert trichothecenes into less toxic glycosides. Microbial biotransformations of trichothecenes include acetylation, deacetylation, oxidation, de-epoxidation, epimerization, and glucosylation. Genomics & phylogenetics: We are using comparative genomic analyses to assess relationships among Fusarium species, to develop genetic markers to distinguish between species, and to determine genetic potential for production of mycotoxins and other secondary metabolites. The distribution of mycotoxin biosynthetic genes varies widely among Fusarium species, and has been shaped by vertical inheritance, gene loss, horizontal transfer, and gene duplication. Phylogenetic species delineation has resolved relationships among many taxa, and revealed the presence of additional taxa compared to classifications based on morphological and biological species concepts. Fungal biology: We are investigating the potential for reducing mycotoxin accumulation by manipulating Fusarium genetic regulatory mechanisms. We are testing RNA interference (RNAi) technology as a means of downregulating deoxynivalenol biosynthesis. Plant-pathogen-environment: Epidemiology of Fusarium head blight and accumulation of mycotoxins are directly related to climate. We have found that growth at elevated CO2 concentrations alters the accumulation of wheat defense signaling phytohormones and pathogenesis-related (PR) gene transcript levels following Fusarium inoculation. Phytobiome: Fusarium species interact not only with plants, but also with a host of other organisms in the phytobiome. We are using amplicon sequencing to profile microbiomes associated with wheat and with Fusarium, with the expectation of revealing novel potential biocontrol organisms, or community-level characteristics that could impede pathogen success.