1. Plant Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1090GE Amsterdam, The Netherlands
2. Biosystematics Group, Wageningen University, 6708 PB Wageningen, The Netherlands
3. Laboratory of Plant Physiology, Wageningen University, 6708 PB Wageningen, The Netherlands
4. Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1090GE Amsterdam, The Netherlands
5. DuPont Pioneer, Johnston, Iowa 50131
6. Department of Biology, Duke University, Durham, North Carolina 27708