Atreya, C.D., Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, United States
Raccah, B., Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, United States
Pirone, T.P., Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, United States

A nonaphid transmissible (NAT) variant of tobacco vein mottling virus (TVMV) was used to test the hypothesis that the viral coat protein (CP) plays a role in determining aphid transmissibility. Comparison of the nucleotide sequences in the coat protein cistron of an aphid transmissible isolate (TVMV-AT) with that of TVMV-NAT revealed a single nucleotide difference (G → A) at position 8445; this alters a single amino acid residue (G → E) at position 2747. A cDNA fragment representing the CP region of TVMV-NAT was substituted into the CP region of a full-length cDNA clone of TVMV-AT, and transcribed RNA was inoculated to tobacco plants. Aphids were unable to transmit the resultant hybrid virus which had the TVMV-NAT coat protein, although the concentration and infectivity of the hybrid virus in the source plants were similar to those of TVMV-AT. This is the first direct demonstration that a CP mutation affects aphid transmissibility of a potyvirus. © 1990.