1. Department of Plant Pathology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
2. Laboratoire des Interactions Plantes Microorganismes, CNRS-INRA UMR215, Chemin de Borde Rouge BP27, 31326 Castanet-Tolosan, Cedex, France.
3. Institute of Genetics, Biological Research Center of the Hungarian Academy of Sciences, H-6701 Szeged, Post Office Box 521, Hungary.
4. Institute of Genetics, Agricultural Biotechnology Centre, H-2100 Godollo, Hungary.
5. Department of Biological Sciences, Stanford University, Palo Alto, CA 94305, USA.