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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Toxicology & Mycotoxin Research » Research » Research Project #430468

Research Project: Eliminating Fusarium Mycotoxin Contamination of Corn by Targeting Fungal Mechanisms and Adaptations Conferring Fitness in Corn and Toxicology and Toxinology Studies of Mycotoxins

Location: Toxicology & Mycotoxin Research

Project Number: 6040-42000-043-00-D
Project Type: In-House Appropriated

Start Date: Mar 17, 2016
End Date: Mar 16, 2021

Objective:
1. Determine the evolutionary history and molecular genetics of metabolic and developmental features enhancing the fitness of mycotoxigenic Fusarium (F.) species, including such areas as xenobiotic tolerance, denitrification, and nitric oxide detoxification and the contribution to greenhouse gas emission. 1.1. Identify and characterize hydrolytic lactamases conferring adaptive advantages to F. verticillioides. 1.2. Determine if F. verticillioides produces quorum sensing or quorum sensing inhibitory compounds in vitro and during endophytic colonization of corn. 1.3. Evaluate denitrification by Fusarium species and its impact on competitive fitness, in planta production of mycotoxins, and the production of the potent greenhouse gas, nitrous oxide (N2O). 2. Evaluate the influence of a common niche on the evolution and adaptation of two co-occurring, seed-borne, metabolically active maize endophytes, Acremonium (A.) zeae and Fusarium (F.) verticillioides. 2.1. Utilize comparative genomics to determine if F. verticillioides and A. zeae share gene clusters or other features that correlate to corn as their common host. 2.2. Evaluate competitive interactions between F. verticillioides and A. zeae and profile their transcriptional and metabolic responses. 3. Develop and improve control strategies for mycotoxin contamination by targeting fungal-specific enzymatic activities, using molecular technologies such as host-induced gene silencing. 3.1. Develop and express RNAi silencing constructs for in vitro growth inhibition of F. verticillioides. 3.2. Develop and transform into corn functional vector(s) for host-induced gene silencing (HIGS). 3.3. Testing transgenic corn lines for resistance to F. verticillioides. 4. Determine the interactions between fumonisin exposure and dietary factors on fetal and postnatal development using animal models to provide basic information for ongoing translational human studies. 5. Determine the efficacy of cooking methods to detoxify mycotoxins in co-contaminated corn using an in vivo rodent bioassay approach incorporating biomarkers.

Approach:
1. Lactamase genes in Fusarium (F.) verticillioides confer resistance to environmental lactam-containing antibiotic compounds. F. verticillioides metabolites impact quorum sensing related activities. Fusarium species, notably F. verticillioides, have an active denitrification pathway that is linked to nitric oxide detoxification. 2. Association of F. verticillioides and Acremonium (A.) zeae with the common host (corn) resulted in the two fungi sharing highly homologous genes or gene clusters. F. verticillioides and A. zeae antagonistically interact with distinct transcriptional and metabolic reprogramming. 3. Construct silencing vectors, express in vitro, and conduct assays exposing F. verticillioides to the RNAi transcripts. Silencing constructs having in vitro efficacy will be transformed into corn. Lines of transformed corn will be screened for reduced infection, disease, and fumonisin accumulation. 4. Compare dose-response in mouse strains sensitive (LM/Bc) and insensitive (SWV) to neural tube defect induction by fumonisin B1. Compare dose-response for neural tube defect induction and selected gene expressions in fumonisin B1-exposed mice fed folate deficient or folate sufficient diets. Compare neonatal growth rates in offspring of mice fed diets containing fumonisins. 5. Determine the efficacy of alkaline cooking (nixtamalization) to detoxify corn contaminated with aflatoxin alone or co-contaminated with aflatoxin and fumonisin using a rat feeding bioassay.