Project Number: 5010-42000-050-000-D
Project Type: In-House Appropriated
Start Date: Jan 19, 2016
End Date: Jan 4, 2021
Objective 1: Use comparative phylogenomic approaches to enable accurate identification of mycotoxigenic Fusarium and to elucidate components of Fusarium genomes that are responsible for variation in mycotoxin production. Sub-objectives 1.1 through 1.3 are as follows: 1.1 – Develop a DNA sequence database that facilitates accurate identification of all toxigenic Fusarium species; 1.2 – Determine whether mycotoxin biosynthetic gene clusters and genetic networks that regulate cluster expression differ in their distributions among Fusarium species; 1.3 – Determine whether F. verticillioides has genes that repress fumonisin production. Objective 2: Develop and utilize liquid chromatography-mass spectrometry (LC-MS) approaches for metabolomic analysis of Fusarium verticillioides infection of maize. Sub-objective 2.1 and 2.2 are as follows: 2.1 – Develop workflows for untargeted analyses of the metabolomes of maize, F. verticillioides, and the maize-F. verticillioides interaction; and 2.2 – Identify metabolic biomarkers for high and low levels of F. verticillioides-induced disease in maize. Objective 3: Identify and characterize plant and fungal factors that can impact mycotoxin contamination via their effects on plant disease development. Sub-Objective 3.1 through 3.4 are as follows: 3.1 – Determine how primary sequence and secondary structure of fungal polyglycine hydrolases affect the inhibitory activity of this class of proteases against plant chitinases; 3.2 – Isolate and identify ChitA alloform-specific proteases secreted by the fungi Stenocarpella maydis and Trichoderma viride; 3.3 – Elucidate the role of plant class IV chitinases in maize-fungus interactions; and 3.4 – Identify candidate receptor and regulatory genes that mediate oxylipin-induced changes in expression of fumonisin biosynthetic genes and fumonisin production in F. verticillioides. Objective 4: Identify and characterize components of fungus-fungus interactions that contribute to or inhibit mycotoxin contamination of crops. Sub-objective 4.1 through 4.3 are as follows: 4.1 – Sample across different climate zones to identify novel fungal endophytes of maize that inhibit growth and/or fumonisin production in F. verticillioides; 4.2 – Identify candidate genes in Talaromyces that are responsible for inhibition of growth in F. verticillioides; and 4.3 – Determine whether production of fumonisins and other mycotoxins contributes to the competitiveness of F. verticillioides with other Fusarium species.
The fungus Fusarium is of concern to agriculture because it can cause crop diseases and produce mycotoxins, including three (fumonisins, trichothecenes, and zearalenone) that are among the mycotoxins of greatest concern to food and feed safety. Mycotoxin contamination and crop diseases caused by Fusarium result from a combination of factors, including species of Fusarium, crop species/cultivar, other microbes, and the environment. We will use multiple approaches to identify critical components of Fusarium biology that contribute to crop diseases and mycotoxin contamination, with an emphasis on fumonisins produced by Fusarium verticillioides. We will use genomics to identify genetic markers that provide an unprecedented ability to identify diverse Fusarium species and to resolve phylogenetic relationships among species. We will also use genomics to elucidate the genetic potential of diverse Fusarium species to produce mycotoxins as well as the genetic mechanisms that affect distribution of mycotoxin biosynthetic genes. In addition, we will use mutagenesis to identify genes that suppress fumonisin production in F. verticillioides. Interactions of Fusarium and crops that lead to mycotoxin contamination likely result, in part, from metabolites produced by each organism. Thus, we will use mass spectrometry-based metabolomics to identify metabolites formed during the interaction of F. verticillioides and maize to determine which metabolites are critical for fumonisin contamination. We will also employ a transcriptomics approach to elucidate the effects of one class of plant metabolites, oxylipins, on fumonisin production in F. verticillioides. Because Fusarium mycotoxin levels are typically higher in crops with high levels of Fusarium-incited diseases, improving crop disease resistance will likely reduce mycotoxin contamination as well. Plant chitinases are enzymes that degrade chitin, an essential component of fungal cell walls, and likely contribute to fungal disease resistance. To elucidate how chitinases can be manipulated to improve this resistance, we will use proteomics to study the interaction of maize chitinases and fungal proteases that inactivate chitinases. We will also use classical mycological methods and DNA-based phylogenetic analyses to evaluate the range of fungal endophytes that occur in maize under diverse environmental conditions and to identify endophytes that can inhibit growth and/or fumonisin production in F. verticillioides. We will also use transcriptomics to determine the mechanism by which the fungal endophyte Talaromyces inhibits F. verticillioides. Finally, we will use quantitative polymerase chain reaction (PCR) to determine whether mycotoxin contamination contributes to the ability of F. verticillioides to compete with other maize-associated fungi.