1. Laboratory of Genetics, Wageningen Agricultural University, Dreyenlaan 2, 6703 HA Wageningen, The Netherlands
2. Department of Environmental Sciences, Section Soil Science and Plant Nutrition, P.O. Box 8005, 6700 EC Wageningen, The Netherlands
3. Centraalbureau voor Schimmelcultures, Julianalaan 67, 2628 BC Delft, The Netherlands