title: Mutations to LmIFRD affect cell wall integrity, development and pathogenicity of the ascomycete Leptosphaeria maculans.
abstract: Maintaining cell wall integrity is essential for fungal growth and development. We describe two mutants with altered expression of a gene, LmIFRD, from the ascomycete Leptosphaeria maculans. Truncation of the LmIFRD transcript in a T-DNA insertional mutant led to slower germination, less sporulation and loss-of-pathogenicity towards Brassica napus, whereas silencing of the LmIFRD transcript led to increased germination, sporulation and earlier infection. The increased tolerance to cell wall lysing enzymes and cell wall-disrupting compounds of the T-DNA mutant contrasts with decreased tolerance of the silenced mutant and suggests altered cell wall integrity and accessibility to 1,3-linked glucan and chitin. Lectin binding experiments and monosaccharide analysis revealed altered polysaccharide content and structure within the cell wall of the LmIFRD mutants, notably increased 1,3-linked galactose and chitin within the cell wall of the T-DNA mutant. This is the first analysis of monosaccharide linkage composition of cell walls of spores and mycelia for any dothideomycete.
authors.affiliation: School of Botany, The University of Melbourne, Vic., Australia.
authors.forename: Angela P
authors.initials: AP
authors.lastname: Van de Wouw
authors.forename: Filomena A
authors.initials: FA
authors.lastname: Pettolino
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Howlett
authors.forename: Candace E
authors.initials: CE
authors.lastname: Elliott
mesh_terms: D001203:Ascomycota / Q000737:chemistry / Q000472:pathogenicity* / Q000502:physiology* / Q000648:ultrastructure; D029688:Brassica napus / Q000382:microbiology*; D002236:Carbohydrate Conformation; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D002686:Chitin / Q000737:chemistry / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D005800:Genes, Fungal; D037102:Lectins / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D009005:Monosaccharides / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D025282:Mycelium / Q000737:chemistry / Q000648:ultrastructure; D013172:Spores, Fungal / Q000737:chemistry / Q000648:ultrastructure; D014774:Virulence
chemical_list: D004269:DNA, Bacterial; D037102:Lectins; D009005:Monosaccharides; C036483:T-DNA; D002686:Chitin