SORGHUM VERTICILLIFLORUM: A NATURAL HOST OF SORGHUM YELLOW BANDING VIRUS IN VENEZUELA
M.J. Garrido, R.M. Cuello, F. Centeno, G.E. Trujillo
Apparently virus- infected Sorghum verticilliflorum (wild sorghum) plants were observed at Maracay, Aragua State. These plants showed yellow speckles, chlorotic streaks and bands, stunting, and light necrosis. Symptomatic plants were collected, and extracts from these plants were mechanically inoculated to a range of plant species. A virus was transmitted at relatively low rate (7%) to wild sorghum and sorghum (S. bicolor) plants. Symptoms appeared 17-24 days after inoculation. Infected wild sorghum plants were sterile or had only a few spikelets. The virus was not transmitted by Rhopalosiphum maidis or Peregrinus maidis, nor was it found in progeny of seed from an infected plant. In agar double immunodiffusion tests forty-two isolates from wild sorghum reacted positively with antiserum to Sorghum yellow banding virus, SrYBV (Garrido et al., 2000). Examination of clarified viral concentrate of some isolates consistently revealed isometric particles 25 nm in diameter. SDS-PAGE analysis of protein extracted from these preparations yielded a single band with a mol. wt. of approximately 29 kDa. Based on these results, the virus is considered to be SrYBV (Garrido et al., 2000; Klaassen and Falk, 1989). Probably, S. verticilliflorum is an important host in the epidemiology of SrYBV in Venezuela, since it is a widely distributed weed in the country. This is the first report of S. verticilliflorum as natural host of SrYBV.