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  • The EMBO Journal (2000) 19, 3204 - 3214
  • doi:10.1093/emboj/19.13.3204



There is an Erratum (November 2000) associated with this Article.

Cultivar-specific avirulence and virulence functions assigned to avrPphF in Pseudomonas syringae pv. phaseolicola, the cause of bean halo-blight disease

George Tsiamis1, John W Mansfield1, Ruth Hockenhull1, Robert W Jackson2, Ane Sesma3, Evangelos Athanassopoulos1, Mark A Bennett1, Conrad Stevens1, Alan Vivian2, John D Taylor3 and Jesus Murillo4

  1. Department of Biological Sciences, Wye College, University of London, Ashford, Kent TN25 5AH UK
  2. Department of Biological and Biomedical Sciences, University of the West of England, Coldharbour Lane, Bristol BS16 1QY UK
  3. Horticulture Research International, Wellesbourne, Warwick CV35 9EF, UK
  4. Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra, 31006 Pamplona, Spain

Correspondence to:

John W Mansfield, E-mail: j.mansfield@wye.ac.uk

Received 6 March 2000; Accepted 10 May 2000; Revised 3 May 2000

The avrPphF gene was cloned from Pseudomonas syringae pathovar phaseolicola (Pph) races 5 and 7, based on its ability to confer avirulence towards bean cultivars carrying the R1 gene for halo-blight resistance, such as Red Mexican. avrPphF comprised two open reading frames, which were both required for function, and was located on a 154 kb plasmid (pAV511) in Pph. Strain RW60 of Pph, lacking pAV511, displayed a loss in virulence to a range of previously susceptible cultivars such as Tendergreen and Canadian Wonder. In Tendergreen virulence was restored to RW60 by avrPphF alone, whereas subcloned avrPphF in the absence of pAV511 greatly accelerated the hypersensitive resistance reaction caused by RW60 in Canadian Wonder. A second gene from pAV511, avrPphC, which controls avirulence to soybean, was found to block the activity of avrPphF in Canadian Wonder, but not in Red Mexican. avrPphF also conferred virulence in soybean. The multiple functions of avrPphF illustrate how effector proteins from plant pathogens have evolved to be recognized by R gene products and, therefore, be classified as encoded by avirulence genes.

  • Keywords:

    • avirulence,
    • disease resistance,
    • gene-for-gene interactions,
    • hypersensitive reaction,
    • virulence