[1] John Innes Ctr Plant Sci Res, Norwich NR4 7UH, Norfolk, England
[2] Univ Nottingham, NASC, Div Plant Sci UP, Nottingham NG7 2RD, England
[3] Scottish Crop Res Inst, Dundee DD2 5DA, Scotland
[4] Cornell Univ, Dept Plant Breeding, Ithaca, NY 14853 USA
[5] AFRC, Inst Grassland & Environm Res, Aberystwyth SY23 3EB, Ceredigion, Wales