1. The New Zealand Institute for Plant and Food Research Limited; Private Bag 4704 Christchurch 8140 New Zealand
2. Department of Microbiology and Immunology; University of Otago; PO Box 56 Dunedin 9054 New Zealand
3. Bioprotection Research Centre; Lincoln University; PO Box 84 Canterbury 7647 New Zealand
4. James Hutton Institute; Invergowrie Dundee DD2 5DA UK