Title: Fusarium verticillioides chitin synthases CHS5 and CHS7 are required for normal growth and pathogenicity Authors
Submitted to: Current Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 3, 2011
Publication Date: January 19, 2011
Repository URL: http://hdl.handle.net/10113/49686
Citation: Larson, T.M., Kendra, D.F., Busman, M., Brown, D.W. 2011. Fusarium verticillioides chitin synthases CHS5 and CHS7 are required for normal growth and pathogenicity. Current Genetics. 57(3):177-189. Interpretive Summary: This research determined that eight genes were present in a fungal pathogen of corn, Fusarium verticillioides, encoding chitin synthases belonging to seven defined classes. Chitin synthases are enzymes which synthesize chitin which is used in the building of fungal cell walls. These enzymes are necessary for proper growth and development of the fungi. We specifically deleted two of the genes in order to determine the function of the genes. Deletion of the targeted genes reduced the ability of the fungus to cause disease on corn. The deletion of these genes also caused the fungus to be more sensitive to chemical stresses. This will allow for greater specificity in the design and use of antifungal chemicals to help control the fungus on corn crops.
Technical Abstract: Fusarium verticillioides is both an endophyte and a pathogen of maize and is a health threat in many areas of the world because it can contaminate maize with fumonisins, a toxic secondary metabolite. We identified eight putative chitin synthase (CHS) genes in F. verticillioides genomic sequence and phylogenetic evidence show they group to seven established CHS gene classes. We targeted two CHSs (CHS5 and CHS7) for deletion analysis and found that both are required for normal hyphal growth and maximal disease of maize seedlings and ears. CHS5 and CHS7 encode a putative class V and class VII fungal chitin synthase respectively and are located adjacent to each other and are divergently transcribed. Fluorescent microscopy found that both CHS deficient strains produce balloon shaped hyphae while growth assays indicated that they were more sensitive to cell wall stressing compounds (e.g. the antifungal compound Nikkomycin Z) than wild type. Pathogenicity assays on maize seedlings and ears indicated that both strains were significantly reduced in their ability to cause disease. Our results demonstrate the both CHS5 and CHS7 are necessary for proper hyphal growth and pathogenicity of F. verticillioides on maize.