Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2005
Publication Date: June 19, 2005
Citation: French, R.C., Stenger, D.C. 2005. Patterns of temporal variation in parallel wheat streak mosaic virus lineages passaged at high mo1 suggest that genetic bottlenecks are intrinsic to serial transmission. American Society for Virology Meeting. Oral presentation, not published in journal. Technical Abstract: Compositions of Wheat streak mosaic virus (WSMV) populations, derived from a common founding event and subjected to serial passage at high multiplicity of infection (MOI), were evaluated. Limiting dilution inoculation generated a founding population. Parallel lineages derived from this were sampled at passage 9 and at passage 15, with or without mixing of lineages at passage 10. Temporal changes in sequence polymorphism within each population were assessed by sequencing 17-21 clones each of a 1371 nt region encompassing the entire coat protein cistron and 3' UTR. The frequency of unique substitutions (singletons) within populations ranged from 1.4 to 8.0 X 10-4/nt, but did not consistently increase or decrease with passage. Shared substitutions (19 nonsynonymous, 10 synonymous, and 3 noncoding) occurred at 32 sites among 44 haplotypes, although only four substitutions became fixed within a population and nearly one third (10/32) remained at frequencies of 10% or less. Shared substitutions were randomly distributed along the entire genomic region. Transitions exceeded transversions by 5.4 : 1, and A to G and U to C transitions were clearly favored. Haplotype composition of each population was unique but the complexity of each population varied unpredictably, in that the number and frequency of haplotypes within a lineage were not correlated with number of passages removed from the founding population or whether the population was derived from a single or mixed lineage. The simplest explanation is that plant virus lineages, even those propagated at high MOI, are subject to frequent and stringent genetic bottlenecks during systemic movement that result in stochastic changes in population structure upon serial passage.