Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2006
Publication Date: 9/1/2006
Citation: Ali, A., Li, H., Schneider, W.L., Sherman, D.J., Gray, S.M., Smith, D., Roossinck, M.J. 2006. Analysis of genetic bottlenecks during horizontal transmission of cucumber mosaic virus. Journal of Virology. 80:8345-8350 Interpretive Summary: RNA viruses are known to be incredibly adaptable, making them difficult pathogens to combat. In plant viruses this adaptability often results in the breakdown of host resistance. This adaptability is due in part to high levels of genetic variability in viral populations. However, the amount of variability in viral populations is limited by “bottlenecks” in the viral life cycle. Bottlenecks occur when a small number of individuals from a large population are used to initiate a new population. This paper describes experiments that demonstrate that aphid transmission of cucumber mosaic virus (CMV) acts as a bottleneck, reducing the overall population variation. In addition, the experiments described demonstrate that the bottleneck effect does not take place during aphid feeding on the CMV infected source plant. Rather, the bottleneck appears to occur when the aphid inoculates a healthy plant.
Technical Abstract: Genetic bottlenecks may occur in virus populations when only a few individuals are transferred horizontally from one host to another, or when a viral population moves systemically through the vascular system to initiate infection in a new leaf. Genetic bottlenecks during the systemic movement of an RNA plant virus population were reported previously. In this study, we inoculated an artificial population consisting of twelve restriction marker mutants of Cucumber mosaic virus (CMV) onto young leaves of squash plants and used two aphid species, Aphis gossypii and Myzus persicae, to transmit the virus populations from infected source plants to new healthy squash plants. Horizontal transmission by aphid was a significant bottleneck, as the populations in the aphid inoculated plants contained far fewer mutants than the original inoculum source. Additional experiments demonstrated that genetic variation in the artificial population of CMV is not reduced during the acquisition of the virus, but is significantly reduced during the inoculation period.