1. Dpto. Ciencias del Medio Natural; Universidad Pública de Navarra; 31006 Pamplona Spain
2. Laboratory of Plant Physiology; Wageningen University; Wageningen 6703 HA The Netherlands
3. Department of Molecular Systems Biology; University of Vienna; Vienna 1090 Austria
4. Institut de Recherche en Horticulture et Semences; University of Angers; Angers F-49045 France
5. Institut de Recherche en Horticulture et Semences; INRA; Beaucouzé F-49071 France