HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (Papers in Press[PDF]) All Versions of this Article: vir.0.008193-0v1 90/6/1527    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Martín, S. Articles by Moreno, P. Search for Related Content PubMed PubMed Citation Articles by Martín, S. Articles by Moreno, P. Agricola Articles by Martín, S. Articles by Moreno, P.

Contribution of recombination and selection to molecular evolution of Citrus tristeza virus

¹ Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV);
² John Innes Centre;
³ Instituto Valenciano de Investigaciones Agrarias

⁴ E-mail: moreno_pedgom{at}ivia.gva.es

The genetic variation of Citrus tristeza virus (CTV) was analyzed comparing the predominant sequence variants in seven genomic regions (p33, p65, p61, p18, p13, p20, and p23) of 18 pathogenically distinct isolates from seven different countries. Analyses of the selective constraints acting on each codon suggest that most regions were under purifying selection. Phylogenetic analysis show diverse patterns of molecular evolution for different genomic regions. A first clade composed by isolates genetically close to the reference mild isolates T385 or T30 was inferred from all genomic regions. A second clade, mostly comprising virulent isolates, was defined from regions p33, p65, p13, p20, and p23. For regions p65, p61, p18, p13, and p23 a third clade that mostly included South American isolates could not be related with any reference genotype. Phylogenetic relationships among isolates did not reflect their geographical origin, suggesting significant gene flow between geographically distant areas. Incongruent phylogenetic trees for different genomic regions suggested recombination events, an extreme that was supported by several recombination-detecting methods. A phylogenetic network incorporating the effect of recombination showed an explosive radiation pattern for the evolution of some isolates and grouped isolates by virulence. Taken together, the above results suggest that negative selection, gene flow, sequence recombination, and virulence may be important factors driving CTV evolution.

Received 22 October 2008; accepted 12 February 2009.