[1
]Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology,
Ghent University, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium; email:
[2
]U.S. Dairy Forage Research Center, USDA-Agricultural Research Service, Madison, Wisconsin,
53706; email:
[3
]Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, 1850 Chaussée
de Wavre, B-1160 Brussels, Belgium; email: