Metabolomic analysis of the plant pathogenic microbes Fusarium graminearum and F. culmorum

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Many micro-organisms specialise in attacking plants and agricultural crops to complete their lifecycle. Some microbial infections lower crop yields, whilst others lower the quality of the harvested product, for example, causing spots on apples. Both these situations can seriously affect farm profit margins and may in certain countries lead to food shortages. Another group of micro-organisms which attack plants are of even greater concern. This is because during the infection of plant tissue they produce specific toxins, called mycotoxins, which are harmful to human and animal health even when eaten in only modest quantities. The accurate testing for the presence of these mycotoxins in bulk grain as well as raw fruit and vegetable products is very difficult and is also expensive. A micro-organism called the Fusarium scab fungus is of growing international concern (http://www.scabusa.org) because it infects the flowers of all cereal plant species (wheat, barley, maize and rice) and during these infections the cereal grain becomes contaminated with a highly toxic, water soluble, mycotoxin called DON, commonly known as vomitoxin because of the effects it causes on humans when ingested. Interestingly the Fusarium fungus only produces mycotoxins when it grows inside plant tissue or under conditions in the laboratory which mimic the carbon and nitrogen rich interior of the plant. In this project we wish to understand how the Fusarium fungus switches on mycotoxin production. This has already been explored, by determining whether the expression of each of the 11,640 Fusarium genes is specifically switched on, off or do not alter under mycotoxin inducing conditions. To complement this study, we plan to investigate under precise laboratory conditions what happens to the biochemistry inside the Fusarium fungus as DON production is switched on. We plan to explore in detail the global changes in the small water soluble chemical molecules made inside the Fusarium fungus. To increase our understanding of this process, we also plan to test under the identical conditions up to 100 different mutant strains of the Fusarium fungus which each have a single gene removed. The Fusarium fungus is predicted to have in total 11,640 genes. Therefore we intend only to focus on gene deletion strains which remove different key internal regulators, and other which are known to compromise DON production or plant infection processes. To help interpretation the complex Fusarium results we will modelling the changes in small molecules observed and thereby generate working hypotheses to test by subsequent experimentation. In addition to assist us in interpreting the Fusarium results we will include some comparable experiments with two well/studied species of fungi, namely baker's yeast which grows by budding and a free living filamentous fungus called Neurospora. The research should help us to devise various ways either to stop the Fusarium fungus from infecting cereal crops or from producing mycotoxins in the developing grain.