title: The novel Cladosporium fulvum lysin motif effector Ecp6 is a virulence factor with orthologues in other fungal species.
abstract: During tomato leaf colonization, the biotrophic fungus Cladosporium fulvum secretes several effector proteins into the apoplast. Eight effectors have previously been characterized and show no significant homology to each other or to other fungal genes. To discover novel C. fulvum effectors that might play a role in virulence, we utilized two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) to visualize proteins secreted during C. fulvum-tomato interactions. Three novel C. fulvum proteins were identified: CfPhiA, Ecp6 and Ecp7. CfPhiA shows homology to proteins found on fungal sporogenous cells called phialides. Ecp6 contains lysin motifs (LysM domains) that are recognized as carbohydrate-binding modules. Ecp7 encodes a small, cysteine-rich protein with no homology to known proteins. Heterologous expression of Ecp6 significantly increased the virulence of the vascular pathogen Fusarium oxysporum on tomato. Furthermore, by RNA interference (RNAi)-mediated gene silencing we demonstrate that Ecp6 is instrumental for C. fulvum virulence on tomato. Hardly any allelic variation was observed in the Ecp6 coding region of a worldwide collection of C. fulvum strains. Although none of the C. fulvum effectors identified so far have obvious orthologues in other organisms, conserved Ecp6 orthologues were identified in various fungal species. Homology-based modelling suggests that the LysM domains of C. fulvum Ecp6 may be involved in chitin binding.
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, Wageningen, The Netherlands.
authors.forename: Melvin D
authors.initials: MD
authors.lastname: Bolton
authors.forename: H Peter
authors.initials: HP
authors.lastname: van Esse
authors.forename: Jack H
authors.initials: JH
authors.lastname: Vossen
authors.forename: Ronnie
authors.initials: R
authors.lastname: de Jonge
authors.forename: Ioannis
authors.initials: I
authors.lastname: Stergiopoulos
authors.forename: Iris J E
authors.initials: IJ
authors.lastname: Stulemeijer
authors.forename: Grardy C M
authors.initials: GC
authors.lastname: van den Berg
authors.forename: Orlando
authors.initials: O
authors.lastname: Borrás-Hidalgo
authors.forename: Henk L
authors.initials: HL
authors.lastname: Dekker
authors.forename: Chris G
authors.initials: CG
authors.lastname: de Koster
authors.forename: Pierre J G M
authors.initials: PJ
authors.lastname: de Wit
authors.forename: Matthieu H A J
authors.initials: MH
authors.lastname: Joosten
authors.forename: Bart P H J
authors.initials: BP
authors.lastname: Thomma
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D018533:Biomass; D002963:Cladosporium / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D003001:Cloning, Molecular; D015180:Electrophoresis, Gel, Two-Dimensional; D005658:Fungi / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D015966:Gene Expression Regulation, Fungal; D018551:Solanum lycopersicum / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D020543:Proteome / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D037521:Virulence Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D020543:Proteome; D037521:Virulence Factors