Association of an unusual filamentous virus with leaf crinkle disease of urdbean in Himachal Pradesh.
Detailed studies were conducted to establish the etiology of leaf crinkle disease of urdbean (Vigna mungo) prevalent in Himachal Pradesh. The virus symptoms on artificially inoculated plants were exhibited on the first trifoliate leaves as mild mosaic, followed by leaf crinkling, puckering and enlargement of leaf lamina followed by plant degeneration. The virus was transmitted through seed, sap and aphid vector, Aphis craccivora. Among various virus purification methods, Cavileer buffer based method was found most suitable. Treatment of purified preparation with nucleases indicated the virus genome as RNA with molecular weight of 18.5 to 37.5 kDa. Electron microscopic observations of more than 100 disease samples across the state showed the presence of long filamentous virus particles measuring between 1600 to 2100 nm with a modal length of 1950 nm, thus indicating the involvement of a new virus with leaf crinkle disease though all other properties were almost similar to the earlier descriptions.