1 INRAE, UNICAEN, Normandie Université, UMR 950 Ecophysiologie Végétale, Agronomie et Nutritions N.C.S., SFR Normandie Végétal (FED 4277), Esplanade de la Paix, Caen, France.
2 Department of Plant Breeding, Swedish University of Agricultural Sciences, Lomma, Sweden.
3 Pollen Biotechnology of Crop Plants Group, Biological Research Center Margarita Salas, CIB-CSIC, Madrid, Spain.