Estimation of the size of genetic bottlenecks in cell-to-cell movement of soil-borne wheat mosaic virus and the possible role of the bottlenecks in speeding up selection of variations in trans-acting genes or elements.
Genetic bottlenecks facilitate the fixation and extinction of variants in populations, and viral populations are no exception to this theory. To examine the existence of genetic bottlenecks in cell-to-cell movement of plant RNA viruses, we prepared constructs for Soil-borne wheat mosaic virus RNA2 vectors carrying two different fluorescent proteins, yellow fluorescent protein (YFP) and cyan fluorescent protein (CFP). Coinoculation of host plant leaves with the two RNA2 vectors and the wild-type RNA1 showed separation of the two vector RNA2s, mostly within seven to nine cell-to-cell movements from individual initially coinfected cells. Our statistical analysis showed that the number of viral RNA genomes establishing infection in adjacent cells after the first cell-to-cell movement from an initially infected cell was 5.97 +/- 0.22 on average and 5.02 +/- 0.29 after the second cell-to-cell movement. These results indicate that plant RNA viruses may generally face narrow genetic bottlenecks in every cell-to-cell movement. Furthermore, our model suggests that, rather than suffering from fitness losses caused by the bottlenecks, the plant RNA viruses are utilizing the repeated genetic bottlenecks as an essential element of rapid selection of their adaptive variants in trans-acting genes or elements to respond to host shifting and changes in the growth conditions of the hosts.
Miyashita
Shuhei
S
Asian Natural Environmental Science Center (ANESC), University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. smiyashita@live.jp
Kishino
Hirohisa
H
D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D027465:Chenopodium quinoa / Q000821:virology; D017931:DNA Primers / Q000235:genetics; D019143:Evolution, Molecular; D014644:Genetic Variation; D005822:Genetic Vectors; D016679:Genome, Viral; D049452:Green Fluorescent Proteins / Q000235:genetics; D008164:Luminescent Proteins / Q000235:genetics; D008957:Models, Genetic; D009029:Mosaic Viruses / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D009154:Mutation; D011994:Recombinant Proteins / Q000235:genetics; D012641:Selection, Genetic; D012988:Soil Microbiology; D014908:Triticum / Q000821:virology*
D001426:Bacterial Proteins; C485182:Cyan Fluorescent Protein; D017931:DNA Primers; D008164:Luminescent Proteins; D011994:Recombinant Proteins; C054562:yellow fluorescent protein, Bacteria; D049452:Green Fluorescent Proteins