Experimental evidence indicating that mastreviruses probably did not co-diverge with their hosts

Gordon W. Harkins, Wayne Delport, Siobain Duffy, Natasha Wood, Adérito L. Monjane, Betty E. Owor, Lara Donaldson, Salem Saumtally, Guy Triton, Rob W. Briddon, Dionne N. Shepherd, Edward P. Rybicki, Darren P. Martin, Arvind Varsani

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38 Scopus citations

Abstract

Background. Despite the demonstration that geminiviruses, like many other single stranded DNA viruses, are evolving at rates similar to those of RNA viruses, a recent study has suggested that grass-infecting species in the genus Mastrevirus may have co-diverged with their hosts over millions of years. This "co-divergence hypothesis" requires that long-term mastrevirus substitution rates be at least 100,000-fold lower than their basal mutation rates and 10,000-fold lower than their observable short-term substitution rates. The credibility of this hypothesis, therefore, hinges on the testable claim that negative selection during mastrevirus evolution is so potent that it effectively purges 99.999% of all mutations that occur. Results. We have conducted long-term evolution experiments lasting between 6 and 32 years, where we have determined substitution rates of between 2 and 3 × 10 -4substitutions/site/year for the mastreviruses Maize streak virus (MSV) and Sugarcane streak Réunion virus (SSRV). We further show that mutation biases are similar for different geminivirus genera, suggesting that mutational processes that drive high basal mutation rates are conserved across the family. Rather than displaying signs of extremely severe negative selection as implied by the co-divergence hypothesis, our evolution experiments indicate that MSV and SSRV are predominantly evolving under neutral genetic drift. Conclusion. The absence of strong negative selection signals within our evolution experiments and the uniformly high geminivirus substitution rates that we and others have reported suggest that mastreviruses cannot have co-diverged with their hosts.

Original languageEnglish (US)
Article number104
JournalVirology Journal
Volume6
DOIs
StatePublished - Aug 20 2009

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ASJC Scopus subject areas

  • Virology
  • Infectious Diseases

Cite this

Harkins, G. W., Delport, W., Duffy, S., Wood, N., Monjane, A. L., Owor, B. E., Donaldson, L., Saumtally, S., Triton, G., Briddon, R. W., Shepherd, D. N., Rybicki, E. P., Martin, D. P., & Varsani, A. (2009). Experimental evidence indicating that mastreviruses probably did not co-diverge with their hosts. Virology Journal, 6, [104]. https://doi.org/10.1186/1743-422X-6-104