Duoduo Wang1, Graham B Seymour2. 1. University of Nottingham, School of Biosciences, Division of Plant and Crop Science, Sutton Bonington, Lough, Leics LE12 5RD, UK. 2. University of Nottingham, School of Biosciences, Division of Plant and Crop Science, Sutton Bonington, Lough, Leics LE12 5RD, UK. Electronic address: graham.seymour@nottingham.ac.uk.