5. Over past two decades many more gene sequences many more methods World Wide Web >> answers to more subtle questions

7. “The hypothesis is proposed that all plant viruses in Australia were introduced since European settlement of the Australia continent towards the end of the eighteenth century” N.H.White 1973.

9. Potyviruses genus Potyvirus in Potyviridae 150+ species 15%+ of all named plant virus species infect all types of plants, worldwide transmitted by aphids while probing many transmitted by seed flexuous filamentous particles (RNA 10kb) many potyviruses in Australia

11. 5500 potyvirus sequences in Genbank 100+ potyviruses recorded in Australia coat protein gene sequences of 40+ Australian potyvirus species

12. Why are there so many potyviruses? Where did the Australian potyviruses come from?

22. Hibbertia virus Y

25. Australian potyviruses > two groups Australia and overseas (17) - mostly in crops - twigs of world population (0.2-4.2% var n ) - close to overseas populations (1.1-7.5%) - represent 13 different lineages Australia only (18) – mostly in wild and weeds - branches of word pop n (0.7-15.9% var n ) - distant from nearest (11-26%) - 14/18 are from the BCMV lineage

26. x10 -4 ns/s/yr plum pox virus90y1.4 Oz potyviruses75y1.173

27. 250,000 species of flowering plants 1,800 species ‘domesticated’ (+/-) 100 species important Before 1492 only two of these species found in both Old World and New World coconut and calabash gourd

32. x10 -4 ns/s/yr plum pox virus90y1.4 Oz potyviruses75y1.173 cowpea aphid-borne mosaic virus500y1.397 papaya ringspot virus300y1.25 1.15x10 -4 ns/s/yr radiation 6,600 YBP assuming lineage-specific rates (‘relaxed clock’)

33. potyviruses radiated 6,600 years ago when agriculture was spreading fast especially in Eurasia - agriculture provided large populations of genetically uniform host plants - agriculture thereby fostered aphidines and potyviruses

34. Why are most Australian endemic potyviruses from the BCMV lineage? When did they enter Australia? How did they enter Australia?

35. Hosts of bean common mosaic virus lineage aroids (dasheen, taro, yam) cucurbits (cucumber, melon, squashes) legumes (beans, cowpea, soybean) orchids (vanilla) passifloras

39. Why > 2000YBP? - humans crossed the Wallace line and arrived in Greater Australia 30-40,000ya - climate stable after ice age ended 14-9,000ya - Australia and P-NG separated 6,000ya - Europeans arrived 400ya Macassarese 200ya - Austronesian expansion from 6,000ya

42. Austronesians - adventurers, fishermen, farmers - chickens, pigs, dogs - aroids, nuts, fruits, fibres, woods, etc

43. SUMMARY Potyviruses radiated 6,600 years ago when agriculture was spreading in Eurasia Australian potyviruses came in two waves: - some were carried across the Wallace line >2000ya, probably in Austronesian crops, then spread by aphids and in seed - others arrived in plant materials imported during the past 200 years by the Europeans from all regions of the world

44. The potyviruses of Australia. Archives of Virology DOI 10.1007/s00705-008-0134-6 Gibbs, A. J., Mackenzie, A. M., Wei, K.-J. and Gibbs, M. J. (2008) The Prehistory of Potyviruses: Their Initial Radiation Was during the Dawn of Agriculture. PLoS ONE 3(6): e2523. doi:10.1371/journal.pone.0002523 Gibbs, A.J., Ohshima, K., Phillips, M.J., Gibbs, M.J. (2008) The bean common mosaic virus lineage of potyviruses; where did it arise and when? Archives of Virology? Gibbs, A.J., Trueman, J., Gibbs, M.J. John Armstrong, Carlye Baker, Lute Bos, Mark Clements, Vic Eastop, Denis Fargette, Mathieu Fourment, Pat Gibbs, Bryan Harrison, Roger Jones, Ramon Jordan, Terry Macfarlane, Rick Mumford, Denis Persley, Brendan Rodoni, Len Tessorerio, Anupam Varma, Colin Ward, Les Watson, Josef Vetten.

45. So what? 20 potyviruses entered Australia in <200 yrs 3 potyviruses entered UK during 1970-2004 = c. one significant potyvirus/decade 1970-2004 a total of 234 plant pathogen species arrived in the UK: 157 fungi, 27 oomycetes, 26 viruses, 23 bacteria, one phytoplasma; 53% infect ornamentals, 16% horts, 15% wild, 12% agrics, 2% pasture, 2% trees