1. Department of Plant Biology and Forest Genetics; Uppsala BioCentre; Linnean Centre of Plant Biology in Uppsala; Swedish University of Agricultural Sciences; Box 7080, SE-750 07 Uppsala Sweden
2. Department of Crop Production Ecology; Swedish University of Agricultural Sciences; Box 7043, SE-750 07 Uppsala Sweden
3. Department of Forest Mycology and Plant Pathology; Uppsala BioCentre; Swedish University of Agricultural Sciences; Box 7026, SE-750 07 Uppsala Sweden