1. Danish Institute of Agricultural Sciences, Research Centre Foulum, P.O. Box 50, DK-8830 Tjele, Denmark, and Sorbisense, Agro Business Park, Niels Pedersens Allé 2, DK-8830 Tjele, Denmark
2. van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands