Identification and characterization of virus associated with yellow mosaic disease of Ageratum in Himachal Pradesh

Investigations carried out on yellow mosaic disease of Ageratum houstonianum occurring widely in different districts of Himachal Pradesh revealed that the disease is caused by a virus. The infected plants exhibited vein yellowing followed by yellow vein mosaic pattern, severely infected plants showed necrosis, poor flowering and less seed formation. However, seed germination was not affected by the virus. The virus under study was transmitted through whitefly (Bemisia tabaci) and grafting only to A. houstonianum, A. conyzoides and Abelmoschus esculentus. Immuno-diagnostic studies (ISEM and ELISA) showed positive reaction between the virus under study and the antiserum of Indian cassava mosaic virus revealing the association of Geminivirus with the disease. Electron microscopy of the infected leaves revealed the presence of geminate particles measuring 17-28nm in diameter similar to the virus particles associated with the disease caused by whitefly transmitted gemininvirus.