1. Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, Wageningen 6700 EE, Netherlands.
2. Institute of Sugar Beet Research, Van Konijnenburgweg 24, Bergen op Zoom 4611 HL, Netherlands.
3. Ecology Department, Lawrence Berkeley National Lab, Cyclotron Road 1, Berkeley, CA 94720, USA.
4. Second Genome, Inc., Owens Street 1700, San Francisco, CA 94158, USA.
5. Plant-Microbe Interactions, Department of Biology, Utrecht University, Padualaan 8, Utrecht 3584 CH, Netherlands.