1. Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology (VIB), Ghent University, B–9052 Gent, Belgium (R.M.B., K.V.P., L.D.V., D.I.); Plant Research International, NL–6700 AA Wageningen, The Netherlands (J.H.W.B., S.P.C.G.); and Laboratoire Associé de l'Institut National de la Recherche Agronomique (France), Ghent University, B–9000 Gent, Belgium (G.E.)