DisplayTitle

Genetic Variation and Possible Mechanisms Driving the Evolution of Worldwide Fig mosaic virus Isolates

First author: Department of Plant Pathology, University of California, Davis 95616, and Nebraska Centre for Virology, University of Nebraska, Lincoln 68583; second author: Instituto de Biología Molecular y Celular de Plantas-CSIC-UPV, Valencia, Spain; third and fourth authors: Department of Plant Protection, Agriculture Faculty, Mustafa Kemal University, 31034 Antakya-Hatay, Turkey; fifth author: Department of Plant Pathology, University of California, Davis; and sixth author: Instituto Valenciano de Investigaciones Agrarias, 46113 Moncada, Valencia, Spain.

Fig mosaic virus (FMV) is a multipartite negative-sense RNA virus infecting fig trees worldwide. FMV is transmitted by vegetative propagation and grafting of plant materials, and by the eriophyid mite Aceria ficus. In this work, the genetic variation and evolutionary mechanisms shaping FMV populations were characterized. Nucleotide sequences from four genomic regions (each within the genomic RNAs 1, 2, 3, and 4) from FMV isolates from different countries were determined and analyzed. FMV genetic variation was low, as is seen for many other plant viruses. Phylogenetic analysis showed some geographically distant FMV isolates which clustered together, suggesting long-distance migration. The extent of migration was limited, although varied, between countries, such that FMV populations of different countries were genetically differentiated. Analysis using several recombination algorithms suggests that genomes of some FMV isolates originated by reassortment of genomic RNAs from different genetically similar isolates. Comparison between nonsynonymous and synonymous substitutions showed selection acting on some amino acids; however, most evolved neutrally. This and neutrality tests together with the limited gene flow suggest that genetic drift plays an important role in shaping FMV populations.