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United States Department of Agriculture

Agricultural Research Service

Title: Viral Rna Quasispecies Generated by Transgenically-Expressed Viral Replicase

Authors
item Taylor, M - NOBLE FOUNDATION
item Schneider, William
item Roossinck, M - NOBLE FOUNDATION
item Flasinski, S - MONSANTO

Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2002
Publication Date: June 20, 2002

Technical Abstract: RNA viruses can exist as diverse populations known as quasispecies. The level of diversity (quasispecies cloud size) is characteristic for a give virus-host system. Previously w examined the quasispecies cloud size of Fny-CMV in Nicotiana tabacum as well as several other host species. Here we analyze Fny-CMV populations in transgenic N. tabacum expressing the replicase components 1a and 2a of Fny-CMV to determine if a transgenically expressed replicase would generate a quasispecies that differed from the wt virus quasispecies. Plants were inoculated with transcripts of either RNAs 1, 2 and 3 (the complete viral genome), or RNA 3 alone. The level of diversity was measured by sequence analysis of 1200 nucleotides from about 15 cDNA clones of each population. Both mutation frequency and bias were examined. The populations generated by the transgenic replicase differed from those generated by the wt virus. These studies have important implications Eight species of aphids collected from a peach orchard in Adams Co., PA, were tested for their ability to transmit two Pennsylvania isolates of plum pox potyvirus recovered from infected trees in Adams (PPV-R1) or Franklin Co. (PPV-FF). Clones of each aphid species were reared on herbaceous host plants. Several acquisition and inoculation protocols were tested to enhance non-persistent transmission of PPV. Four species, Myzus persicae, Brachycaudus persicae, Aphis spiraecola, and A. fabae consistently transmitted PPV. Rhopalosiphum padi transmitted occasionally, and Macrosiphum euphorbiae, A. pisum and A. glycines did not transmit PPV in replicated tests. M. persicae and B. persicae consistently transmitted PPV to peach seedlings from mature peach fruits collected from ELISA positive trees in orchards. Results prove that PA isolates of PPV can be transmitted by aphid species occurring in Prunus orchards and verifies the ability of these aphids to transmit PPV from infected fruits for the use of transgenically expressed virus-induced resistance and the effect that wide spread dissemination of such plants may have on the evolution of plant viruses.

Last Modified: 7/23/2014
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