1. Department of Plant Biology, University of California, Berkeley, CA 94720, USA.
2. Department of Genetics, Harvard Medical School, Boston, MA 02115, USA, and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA.
3. Plant Gene Expression Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA 94710, USA
4. CSIRO Division of Plant Industry and Cooperative Research Centre for Plant Science, Canberra, A.C.T., Australia.
5. Sainsbury Laboratory, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK.