Some potyviruses Adrian Gibbs

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• Over past two decades
• many more gene sequences
• many more methods
• World Wide Web
• gtgt answers to more subtle questions

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• 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.

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• 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

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

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

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Hibbertia virus Y
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Hibbertia virus Y
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• Australian potyviruses gt two groups
• Australia and overseas (17) - mostly in crops
• - twigs of world population (0.2-4.2 varn)
• - close to overseas populations (1.1-7.5)
• - represent 13 different lineages
• Australia only (18) mostly in wild and weeds
• - branches of word popn (0.7-15.9 varn)
• - distant from nearest (11-26)
• - 14/18 are from the BCMV lineage

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• x10-4
  ns/s/yr
• plum pox virus 90y 1.4
• Oz potyviruses 75y 1.173

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• 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

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• 
  x10-4 ns/s/yr
• plum pox virus 90y 1.4
• Oz potyviruses 75y 1.173
• cowpea aphid-borne mosaic virus 500y 1.397
• papaya ringspot virus 300y 1.25
• 1.15x10-4 ns/s/yr radiation
  6,600 YBP
• assuming lineage-specific
  rates
• (relaxed clock)

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• 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

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

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

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• Why gt 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

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

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• 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
  gt2000ya, 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

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• 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. doi10.1371/journal.pone.000
  2523
• 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.

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• So what?
• 20 potyviruses entered Australia in lt200 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