Start Date: Apr 25, 2006
End Date: Apr 24, 2011
Objective 1: Pre-harvest control of fumonisin production will be conducted under controlled conditions of soil moisture, soil inoculum content, over time using corn seedlings and plants of three cultivars that will be inoculated with and without our patented bacterial endophyte, Bacillus mojavensis or Trichoderma koningii, each co-inoculated with strains of Fusarium moniliforme. Fumonisin and fusaric acid, and plant performance will be determined under the above conditions. Objective 2: To address the importance of fumonisin on corn development and virulence factor as well as its translocation by plants, several commercial and experimental corn lines will be screened for tolerance or sensitivity to fumonisin, and identified tolerance and sensitive corn lines will be tested for their ability to translocate fumonisin. All plants will be analyzed for fumonisin content using standard chemical procedures and fungal biomass determined by real-time PCR. The mechanism of corn tolerance will be determined with suppression subtraction hybridization of cDNAs and microarray analyses of sensitive and tolerant lines of corn seedlings. Additionally, a specific approach will target corn genes involved in sphingolipid biosynthesis, such as ASC1. Objective 3: Sterile nematode assays, using two or more nematode species, will be used to determine toxic fractions from the tall fescue endophyte-grass association. The nematode assay will be used both with wild-type and novel endophyte-infected tall fescues. Chemical extracts from infected grasses will be used in the bioassay, and all positive extracts will be separated into specific chemical fractions for chemical identification of the toxin responsible for nematode toxicity. Objective 4: Survey both egg and broiler houses (feed, and litter) for the black-spored Aspergillus niger complex, determine if any of these can produce ochratoxin A on one of several media, including corn, and identify positive isolates to species using molecular techniques. Infect corn seedlings with positive A. niger isolates and determine host-parasite interactions, as well as the effects on toxin accumulation in planta, especially when co-infected with fumonisin producing and non-producing strains of F. verticillioides.