1. Department of Botany, PO Box 118526, University of Florida, Gainesville, Florida 32611–8526, USA;
2. Plant Molecular and Cellular Biology Program, PO Box 118526, University of Florida, Gainesville, Florida 32611–8526, USA;
3. San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093–0537, USA;
4. Department of Cell Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd. La Jolla, California 92037, USA