Chitin Synthase with a Myosin-Like Motor Domain Is Essential for Hyphal Growth, Appressorium Differentiation, and Pathogenicity of the Maize Anthracnose Fungus Colletotrichum graminicola

• Published in: Molecular plant-microbe interactions Vol. 20; no. 12; pp. 1555 - 1567
• Main Authors: Werner, S, Sugui, J.A, Steinberg, G, Deising, H.B
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01.12.2007; The American Phytopathological Society
• Subjects: appressoria; Base Sequence; Biological and medical sciences; cell invasion; cell walls; chitin synthase; Chitin Synthase - chemistry; Chitin Synthase - genetics; Chitin Synthase - physiology; Colletotrichum - enzymology; Colletotrichum - growth & development; Colletotrichum - pathogenicity; Colletotrichum graminicola; disease course; force measurement; Fundamental and applied biological sciences. Psychology; fungal cell wall; Fungal plant pathogens; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - physiology; gene expression; Glomerella graminicola; host plants; hyphae; Hyphae - enzymology; Hyphae - growth & development; Hyphae - ultrastructure; infection; microbial growth; mutants; myosin; myosin-like motor domains; pathogenicity; Phytopathology. Animal pests. Plant and forest protection; Protein Structure, Tertiary; Sequence Deletion; Zea mays; Zea mays - microbiology; Colletotrichum graminicola; Monocotyledones; Yeast; Plant pathogen; Microbiology; force measurement; Glycosyltransferases; Chitin synthase; fungal cell wall; Cereal crop; Cell wall; Fungi; Gene; Gramineae; Angiospermae; Myosin; Fungi Imperfecti; Class I histocompatibility antigen; Zea mays; Enzyme; Transferases; Pathogenicity; Isolate; Hexosyltransferases; Spermatophyta; Mutation
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI-20-12-1555

Chitin synthesis contributes to cell wall biogenesis and is essential for invasion of solid substrata and pathogenicity of filamentous fungi. In contrast to yeasts, filamentous fungi contain up to 10 chitin synthases (CHS), which might reflect overlapping functions and indicate their complex lifestyle. Previous studies have shown that a class VI CHS of the maize anthracnose fungus Colletotrichum graminicola is essential for cell wall synthesis of conidia and vegetative hyphae. Here, we report on cloning and characterization of three additional CHS genes, CgChsI, CgChsIII, and CgChsV, encoding class I, III, and V CHS, respectively. All CHS genes are expressed during vegetative and pathogenic development. delta CgChsI and delta CgChsIII mutants did not differ significantly from the wild-type isolate with respect to hyphal growth and pathogenicity. In contrast, null mutants in the CgChsV gene, which encodes a CHS with an N-terminal myosin-like motor domain, are strongly impaired in vegetative growth and pathogenicity. Even in osmotically stabilized media, vegetative hyphae of delta CgChsV mutants exhibited large balloon-like swellings, appressorial walls appeared to disintegrate during maturation, and infection cells were nonfunctional. Surprisingly, delta CgChsV mutants were able to form dome-shaped hyphopodia that exerted force and showed host cell wall penetration rates comparable with the wild type. However, infection hyphae that formed within the plant cells exhibited severe swellings and were not able to proceed with plant colonization efficiently. Consequently, delta CgChsV mutants did not develop macroscopically visible anthracnose disease symptoms and, thus, were nonpathogenic.