1. Genetics; Department of Biology I; Ludwig-Maximilians-University Munich; D-82152 Martinsried Germany
2. Institute of Biology; Department of Genetics; Martin-Luther-University Halle-Wittenberg; D-06099 Halle (Saale) Germany
3. Julius Kühn Institute; Messeweg 11/12 D-38104 Braunschweig Germany