Identification,eDNA cloning and sequencing of a virus causing tobacco veinal necrosis

Identification , cDNA cloning and sequencing of a virus causing tobacco veinal necrosis were carried out during 1 990一1993. The obvious symptom of the infected tobacco was veinal necrosis. Aphid(Myzus persicae)was demonstrated as transmitting vector. The virus only in-fected 8 species of tobacco and Physalis floridana form solanaceae,out of 35 species from 13 families tested.It's thermal inactivation point was 50一55℃,dilution end point was 1 0(-3)-10(-4),and longevity in vitro was 48-72 hours. The virus particles were flexous rods with Sizeof 720×12nm. Scroll,pinwhell and boundle inclusion were found in cytoplasm of leaf tissues of infected tobacco. The virus could react with the antiserum of PVY￣0 by immunoelec-trophoresis test.Purified virus had A_(280)/A_(260)ratio of 0. 82. Using a pair of primers specific to PVY￣N,reverse transcription and PCR were performed.A specific fragment of 0. 80kb corre-sponding in size to the PVY￣N coat protein gene was amplified. T he products of PCR were cloned in plasmid