The novel Cladosporium fulvum lysin motif effector Ecp6 is a virulence factor with orthologues in other fungal species

Authors

  • Melvin D. Bolton,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    2. Department of Plant Pathology, North Dakota State University, Fargo, ND 58105-5012, USA.
    Search for more papers by this author
    • These authors contributed equally.

    • Present address: USDA – ARS, Northern Crop Science Laboratory, Fargo, ND 58105-5677, USA.

  • H. Peter Van Esse,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    2. Centre for BioSystems Genomics (CBSG), PO Box 98, 6700 AB Wageningen, the Netherlands.
    Search for more papers by this author
    • These authors contributed equally.

  • Jack H. Vossen,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    2. Swammerdam Institute for Life Sciences, Mass Spectrometry, Nieuwe Achtergracht 166, 1018 WV Amsterdam, the Netherlands.
    Search for more papers by this author
    • These authors contributed equally.

    • §

      Present address: Plant Research International BV, PO Box 16, 6700 AA Wageningen, the Netherlands.

  • Ronnie De Jonge,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    Search for more papers by this author
  • Ioannis Stergiopoulos,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    Search for more papers by this author
  • Iris J. E. Stulemeijer,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    Search for more papers by this author
  • Grardy C. M. Van Den Berg,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    Search for more papers by this author
  • Orlando Borrás-Hidalgo,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    2. Centre for Genetic Engineering and Biotechnology, PO Box 6162, Havana, 10600, Cuba.
    Search for more papers by this author
  • Henk L. Dekker,

    1. Swammerdam Institute for Life Sciences, Mass Spectrometry, Nieuwe Achtergracht 166, 1018 WV Amsterdam, the Netherlands.
    Search for more papers by this author
  • Chris G. De Koster,

    1. Swammerdam Institute for Life Sciences, Mass Spectrometry, Nieuwe Achtergracht 166, 1018 WV Amsterdam, the Netherlands.
    Search for more papers by this author
  • Pierre J. G. M. De Wit,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    2. Centre for BioSystems Genomics (CBSG), PO Box 98, 6700 AB Wageningen, the Netherlands.
    Search for more papers by this author
  • Matthieu H. A. J. Joosten,

    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    Search for more papers by this author
  • Bart P. H. J. Thomma

    Corresponding author
    1. Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, the Netherlands.
    2. Centre for BioSystems Genomics (CBSG), PO Box 98, 6700 AB Wageningen, the Netherlands.
    Search for more papers by this author

*E-mail bart.thomma@wur.nl; Tel. (+31) 317 484536; Fax (+31) 317 483412.

Summary

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.

Ancillary