1. Laboratory of Plant Genetics, Institute for Molecular Biology and Biotechnology; Vrije Universiteit Brussel (VUB); Pleinlaan 2 B-1050 Brussels Belgium
2. Department of Chemistry, Faculty of Science; Vrije Universiteit Brussel (VUB); Pleinlaan 2 B-1050 Brussels Belgium
3. Department of Molecular Biosciences; University of Oslo; P.O. Box 1041, Blindern 0316 Oslo Norway