School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK. Paul.Wilkinson@bristol.ac.uk.|School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK.|School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK.|The Genome Analysis Centre (TGAC), Norwich Research Park, Norwich, UK.|The Genome Analysis Centre (TGAC), Norwich Research Park, Norwich, UK.|School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK.|School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK.|School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK.|School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK.|National Institute of Agricultural Botany (NIAB), Huntingdon Road, Cambridge, UK.|The Genome Analysis Centre (TGAC), Norwich Research Park, Norwich, UK.|School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK.