Affiliation: | (1) School of Biological Sciences, Royal Holloway University of London, Egham Hill, Egham, Surrey, TW20 OEX, UK;(2) Zeneca Seeds, Jealott's Hill Research Station, Bracknell, Berks, RG12 6EY, UK;(3) Present address: School of Pure and Applied Biology, University of Wales, Cardiff, P.O. Box 915, Cardiff, CF1 3TL, UK |