A mosaic disease of Senna hirsuta induced by a potyvirus in Nigeria.

A virus inducing mosaic and severe leaf malformation, isolated from Senna hirsuta in Nigeria, was studied. The virus had a rather narrow host range, infecting a few species in Caesalpinaceae, Chenopodiaceae and Fabaceae families. The virus was widespread in southern Nigeria with prevalence ranging from 74% to 86.4% in some locations. It was transmitted mechanically and in a non-persistent manner by Myzuspersicae, Aphis craccivora and A. spiraecola. There was no evidence of transmission by seeds. Electron microscopy of leaf dip preparations revealed flexuous rod-shaped particles. The viral coat protein had Mr of 32.5 K. The virus reacted positively with a monoclonal antibody (MAb) to peanut stripe virus specific for potyviruses (members of the Potvvirus genus) and with antisera to turnip mosaic virus (TuMV), potato virus Y (PVY), TuMV, potato virus A (PVA), potato virus V (PVV) and bean yellow mosaic virus (BYMV), but it failed to react with antisera to celery mosaic virrus (CeMV), bean common mosaic virus (BCMV), soybean mosaic virus (SMV), and clover yellow mosaic virus (ClYMV) in plate-trapped ELISA (PTA-ELISA). No positive reaction was obtained when the virus was tested against any of the antisera in double-antibody sandwich ELISA (DAS-ELISA). This is the first report of natural infection of Senna species in Nigeria. The virus, tentatively designated as Senna mosaic virus (SeMV), seems to differ from other viruses previously described from Senna species in the literature and indeed other legume potyviruses in Nigeria.