1. Department of Chemistry, University of Durham, Science Laboratories, South Road, Durham, DH1 3LE, UK
2. Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, UK
3. Syngenta, Jealott's Hill International Research Station, Bracknell, Berks RG42 6EY, UK
4. Department of Biosciences, University of Durham, Science Laboratories, South Road, Durham, DH1 3LE, UK
5. Agriculture, School of Natural and Environmental Sciences, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, UK