1. Department of Biology, Ghent University, 9000 Ghent, Belgium
2. Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
3. VIB-UGent Center for Plant Systems Biology, B-9052 Ghent, Belgium
4. Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium