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Article

  • The EMBO Journal (2004) 23, 2156 - 2165
  • doi:10.1038/sj.emboj.7600224

Published online: 6 May 2004

CITRX thioredoxin interacts with the tomato Cf-9 resistance protein and negatively regulates defence

Susana Rivasa, Alejandra Rougon-Cardoso, Matthew Smoker, Leif Schauserb, Hirofumi Yoshiokac and Jonathan D G Jones

  1. The Sainsbury Laboratory, John Innes Centre, Norwich Research Park, Norwich, UK

Correspondence to:

Jonathan D G Jones, The Sainsbury Laboratory, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK. Tel.: +44 1603 452471; Fax: +44 1603 450011; E-mail: jonathan.jones@sainsbury-laboratory.ac.uk

aPresent address: Institut des Interactions Plantes-Microorganismes, UMR CNRS/INRA, BP 27, Castanet-Tolosan Cedex, France

bPresent address: Department of Computer Science, Bioinformatics Research Center, University of Aarhus, Ny Munkegade, Building 540, 8000 Århus C, Denmark

cPresent address: Plant Pathology Laboratory, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan

Received 10 February 2004; Accepted 6 April 2004

To identify proteins involved in tomato Cf-9 resistance protein function, a yeast two-hybrid screen was undertaken using the cytoplasmic C-terminus of Cf-9 as bait. A thioredoxin-homologous clone, interacting specifically with Cf-9, was identified and called CITRX (Cf-9-interacting thioredoxin). Virus-induced gene silencing (VIGS) of CITRX resulted in an accelerated Cf-9/Avr9-triggered hypersensitive response in both tomato and Nicotiana benthamiana, accompanied by enhanced accumulation of reactive oxygen species, alteration of protein kinase activity and induction of defence-related genes. VIGS of CITRX also conferred increased resistance to the fungal pathogen Cladosporium fulvum in the otherwise susceptible Cf0 tomato. CITRX acts as a negative regulator of the cell death and defence responses induced through Cf-9, but not Cf-2. Recognition of the Cf-9 C-terminus by CITRX is necessary and sufficient for this negative regulation. This is the first study that implicates thioredoxin activity in the regulation of plant disease resistance.

  • Keywords:

    • cell death,
    • Cladosporium fulvum,
    • plant defence,
    • thioredoxin,
    • tomato