IDENTIFICATION OF STRAIN A OF MAIZE-DWARF MOSAIC-VIRUS INFECTING SORGHUM IN VENEZUELA

A sorghum virus isolate collected in an experimental crop at Maracay, Aragua State, was mechanically inoculated to some differential hosts f or identification. The virus infected sorghum (Sorghum bicolor), maize (Zea mays), and johnsongrass (Sorghum halepense), but it didn't infec t oats (Avena sativa), barley (Hordeum vulgare), wheat (Triticum aesti vum), or sugarcane (Saccharum officinarum) cvs CP-31294 and CP-31588. The thermal inactivation point of the virus was 55-60 degrees C, the d ilution end point was 10(-3)-10(-4), and the longevity in vitro was 1- 2 days at 23 degrees C. The virus was transmitted from sorghum to sorg hum in the non-persistent manner by Rhopalosiphum maidis, but it was n ot transmitted through sorghum seed. The virus was purified by a proto col that featured clarification with 5% chloroform, precipitating with 4% polyethylene glycol in 0.3 M NaCl, and centrifugation in 10-40% su crose density gradients. Yield of 10.20 Mg/g of infected corn leaves w ere obtained. The A260/A280 ratio were 1.28. The virus particles appea red as flexuous rods with a mean of 726.80 nm. In agar double-diffusio n tests the viral isolate reacted positively with maize dwarf mosaic v irus strain A (MDMV-A) antiserum, but it didn't react with MDMV-B anti serum. On the basis of these criterions, the sorghum virus isolate cor responds to MDMV-A. This is the first report of this strain in Venezue la.