title: Expression of effector gene SIX1 of Fusarium oxysporum requires living plant cells.
abstract: Fusarium oxysporum is an asexual, soil inhabiting fungus that comprises many different formae speciales, each pathogenic towards a different host plant. In absence of a suitable host all F. oxysporum isolates appear to have a very similar lifestyle, feeding on plant debris and colonizing the rhizosphere of living plants. Upon infection F. oxysporum switches from a saprophytic to an infectious lifestyle, which probably includes the reprogramming of gene expression. In this work we show that the expression of the known effector gene SIX1 of F. oxysporum f. sp. lycopersici is strongly upregulated during colonization of the host plant. Using GFP (green fluorescent protein) as reporter, we show that induction of SIX1 expression starts immediately upon penetration of the root cortex. Induction requires living plant cells, but is not host specific and does not depend on morphological features of roots, since plant cells in culture can also induce SIX1 expression. Taken together, F. oxysporum seems to be able to distinguish between living and dead plant material, preventing unnecessary switches from a saprophytic to an infectious lifestyle.
authors.affiliation: Plant Pathology, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 318, 1098 SM Amsterdam, The Netherlands.
authors.forename: H Charlotte
authors.initials: HC
authors.lastname: van der Does
authors.forename: Roselinde G E
authors.initials: RG
authors.lastname: Duyvesteijn
authors.forename: Pieter M
authors.initials: PM
authors.lastname: Goltstein
authors.forename: Chris C N
authors.initials: CC
authors.lastname: van Schie
authors.forename: Erik M M
authors.initials: EM
authors.lastname: Manders
authors.forename: Ben J C
authors.initials: BJ
authors.lastname: Cornelissen
authors.forename: Martijn
authors.initials: M
authors.lastname: Rep
mesh_terms: D002478:Cells, Cultured; D005656:Fungal Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D005670:Fusarium / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D018551:Solanum lycopersicum / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D052584:Xylem / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins