1. Univ. Grenoble Alpes; CNRS, CEA, INRA, BIG-LPCV; 38054 Grenoble Cedex 9 France
2. Umeå Plant Science Centre; Department of Forest Genetics and Plant Physiology; Swedish University of Agricultural Sciences; Umeå SE S-901 83 Sweden
3. Umeå Plant Science Centre; Department of Plant Physiology; Umeå University; Umeå Sweden