1. Institut National de la Recherche Agronomique, UAGPF, 2163 Avenue de la Pomme de Pin, BP 20619‐Ardon, 45166 Olivet Cedex, France;
2. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden;
3. Universität Hamburg, Zentrum Holzwirtschaft, Abteilung Holzbiologie, Leuschnerstr. 91, 21031 Hamburg, Germany