Submitted to: International Fusarium Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 12/15/2004
Publication Date: 12/15/2004
Citation: Harris, L., Alexander, N.J., Saparno, A., Blackwell, B., Mcalpin, C.E., Desjardins, A.E., Robert, L., Tinker, N., Ouellet, T. 2004. Functional genomics of fusarium graminearum [abstract]. Proceedings of the 2nd International Symposium on Fusarium Head Blight. p. 567. Interpretive Summary:
Technical Abstract: We are conducting gene profiling experiments using Fusarium graminearum, approximately 4.5K uniEST cDNA microarrays and targeted gene disruptions to identify and functionally test candidate genes suspected to be involved in F. graminearum (Fg) pathogenicity. Fourteen F. graminearum cDNA libraries have been constructed from fungal cultures grown under a variety of conditions to generate a collection of approximately 10,000 expressed sequence tags (ESTs) which group into approximately 5,500 contigs/singletons. A 4.5K unigene F. graminearum cDNA microarray has been printed in-house and array hybridization experiments are underway to explore metabolite biosynthesis and genes induced upon plant contact. Initial array hybridizations have compared expression profiles of Fg grown in liquid culture under conditions of trichothecene production over a 12-day period versus Fg under the same conditions at time 0. Metabolite analysis (HPLC/NMR) of ethyl acetate extracts of these liquid cultures has indicated the production of near equimolar amounts of 15A-DON and butenolide. Functional analysis of candidate genes through gene disruption or modification is the focus of a collaborative project between the USDA and Agriculture & Agri-Food Canada. For example, an analysis of Fg ESTs revealed a hotspot of gene expression from a putative biosynthetic gene cluster on Fg genome contig 1.324. Eight consecutive predicted genes, FG08077-FG08084, are represented by a total of 51 Fg ESTs isolated from trichothecene-producing culture conditions. In addition, five of the genes are represented by six ESTs originating from Fg-infected wheat or barley libraries, suggesting these genes are expressed in planta. These genes include an oxidoreductase, a cytochrome P450, an oxygenase, an acetyltransferase, and a transporter. Northern analysis conducted on seven of the eight genes showed coordinated induction of gene expression, beginning at 4 days post induction and peaking at approximately 10 days post induction in liquid culture. Expression analysis of the eighth gene is in progress. Four of these genes have been initially targeted for gene disruption.