1. Laboratoire de Biologie Cellulaire, Institut Jean Pierre Bourgin, Institut National de la Recherche Agronomique (INRA), 78026 Versailles Cedex, France.
2. Plateforme de Cytologie et d'Imagerie Végétale, Institut Jean Pierre Bourgin, INRA, 78026 Versailles Cedex, France.
3. Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
4. Department of Genetics and Biotechnology, University of Aarhus, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.