1. Ghent University, Department of Plant Biotechnology and Bioinformatics, B-9052 Gent, Belgium
2. VIB Center for Plant Systems Biology, VIB, B-9052 Gent, Belgium
3. Department of Plant Production, Faculty of Bioscience Engineering, Ghent University, B-9000 Gent, Belgium
4. Carlsberg Research Laboratories, 1799 Copenhagen V, Denmark
5. Department of Biology, The University of Copenhagen, Copenhagen DK-2200, Denmark