title: Rho1 has distinct functions in morphogenesis, cell wall biosynthesis and virulence of Fusarium oxysporum.
abstract: Rho-type GTPases regulate polarized growth in yeast by reorganization of the actin cytoskeleton and through signalling pathways that control the expression of cell wall biosynthetic genes. We report the cloning and functional analysis of rho1 from Fusarium oxysporum, a soilborne fungal pathogen causing vascular wilt on plants and opportunistic infections in humans. F. oxysporum strains carrying either a Deltarho1 loss-of-function mutation or a rho1(G14V) gain-of-function allele were viable, but displayed a severely restricted colony phenotype which was partially relieved by the osmotic stabilizer sorbitol, indicating structural alterations in the cell wall. Consistent with this hypothesis, Deltarho1 strains showed increased resistance to cell wall-degrading enzymes and staining with Calcofluor white, as well as changes in chitin and glucan synthase gene expression and enzymatic activity. Re-introduction of a functional rho1 allele into the Deltarho1 mutant fully restored the wild-type phenotype. The Deltarho1 strain had dramatically reduced virulence on tomato plants, but was as virulent as the wild type on immunodepressed mice. Thus, Rho1 plays a key role during fungal infection of plants, but not of mammalian hosts.
authors.affiliation: Departamento de Genetica, Universidad de Córdoba, Campus de Rabanales, Edificio Gregor Mendel, 14071 Córdoba, Spain.
authors.forename: Ana Lilia
authors.initials: AL
authors.lastname: Martínez-Rocha
authors.forename: M Isabel G
authors.initials: MI
authors.lastname: Roncero
authors.forename: Adriana
authors.initials: A
authors.lastname: López-Ramirez
authors.forename: Marçal
authors.initials: M
authors.lastname: Mariné
authors.forename: Josep
authors.initials: J
authors.lastname: Guarro
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Martínez-Cadena
authors.forename: Antonio
authors.initials: A
authors.lastname: Di Pietro
mesh_terms: D000483:Alleles; D000818:Animals; D002473:Cell Wall / Q000378:metabolism*; D002687:Chitin Synthase / Q000378:metabolism; D003470:Culture Media; D003520:Cyclophosphamide / Q000009:adverse effects; D005656:Fungal Proteins / Q000502:physiology*; D005670:Fusarium / Q000166:cytology / Q000201:enzymology / Q000254:growth & development / Q000472:pathogenicity; D005800:Genes, Fungal; D005964:Glucosyltransferases / Q000378:metabolism; D025301:Hyphae / Q000254:growth & development; D016867:Immunocompromised Host; D018551:Solanum lycopersicum / Q000382:microbiology; D051379:Mice; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009181:Mycoses / Q000382:microbiology*; D020741:rho GTP-Binding Proteins / Q000502:physiology*
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D003520:Cyclophosphamide; D005964:Glucosyltransferases; C040232:glucan synthase; D002687:Chitin Synthase; D020741:rho GTP-Binding Proteins