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United States Department of Agriculture

Agricultural Research Service

Research Project: Physiology and Genetic Improvement of Small Fruit Crops Title: Transmission biology of Raspberry latent virus, a plant reovirus vectored by the aphid Amphorophora agathonica

Authors
item Quito-Avila, D -
item Lightle, D -
item Lee, Jana
item Martin, Robert

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 6, 2012
Publication Date: May 1, 2012
Citation: Quito-Avila, D.F., Lightle, D., Lee, J.C., Martin, R.R. 2012. Transmission biology of Raspberry latent virus, a plant reovirus vectored by the aphid Amphorophora agathonica. Phytopathology. 102:547-553.

Interpretive Summary: Raspberry latent virus (RpLV) is a newly characterized reovirus found in commercial raspberry fields in the Pacific Northwest (PNW) that is involved in causing severe crumbly fruit in red raspberry. RpLV is in the family Reoviridae and related most closely to Rice ragged stunt virus (RRSV), the type member of the genus Oryzavirus. All known plant viruses in the Reoviridae are transmitted by leafhoppers or plant hoppers. The sequence of RpLV varied from RRSV or other plant reoviruses, suggesting that RpLV is a possible member of a new genus in the Reoviridae. After several failed attempts to transmit RpLV using leafhoppers found on raspberry plants, the large raspberry aphid was tested as a vector of the virus. In three separate tests this aphid was able to transmit RpLV from raspberry to raspberry, albeit at a low frequency. Using absolute and relative quantification methods, it was shown that the virus titer in aphids continued to increase after the acquisition period even when aphids were serially transferred onto fresh healthy plants on a daily basis, which shows that the virus replicates in the aphid. Transmission experiments determined that RpLV has a 6-day latent period in the aphid before it becomes transmissible; however, it was not transmitted transovarially to the next generation. To our knowledge, this is the first report of a plant reovirus transmitted by an aphid, and we propose RpLV represent a new virus genus in the Reoviridae family. The proposed genus name is Raslavirus for Raspberry latent virus. Knowing that the aphid transmits this virus will aid in developing effective management strategies to control its spread.

Technical Abstract: Raspberry latent virus (RpLV) is a newly characterized reovirus found in commercial raspberry fields in the Pacific Northwest (PNW). Phylogenetic analyses showed that RpLV is related most closely to Rice ragged stunt virus (RRSV), the type member of the genus Oryzavirus. However, the conserved nucleotide termini of the genomic segments of RpLV did not match those of RRSV or other plant reoviruses, suggesting that RpLV is a possible member of a new genus in the Reoviridae. Thus far, all members of the plant reoviruses are transmitted in a replicative persistent manner by several species of leafhoppers or planthoppers. After several failed attempts to transmit RpLV using leafhoppers found on raspberry plants, Amphorophora agathonica Hottes, the large raspberry aphid commonly found in the PNW, was tested as a vector of the virus. Few plants tested positive for the virus when inoculated with groups of 50 viruliferous aphids, suggesting that aphids are inefficient vectors of RpLV. Using absolute and relative quantification methods, it was shown that the virus titer in aphids continued to increase after the acquisition period even when aphids were serially transferred onto fresh healthy plants on a daily basis. Transmission experiments determined that RpLV has a 6-day latent period in the aphid before it becomes transmissible; however, it was not transmitted transovarially to the next generation. To our knowledge this is the first report of a plant reovirus transmitted by an aphid.

Last Modified: 12/21/2014
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