1985 Volume 51 Issue 4 Pages 459-464
Both type A and type B viruses isolated from downy mildew-diseased rice plants contained single-stranded RNA (ssRNA) as determined by susceptibility to formaldehyde and RNase A, resistance to DNase I and fluorescence with two dyes, Hoechst 33258 and acridine orange. Type A virus had two species of polypeptides with molecular weights (MWs) 43×103 and 39×103 and three segments of ssRNA with WMs 1.1×106, 0.7×106, and 0.33×106. The relative amounts of the largest two RNAs were similar in all isolates but that of the smallest RNA varied among the isolates. Type B virus had one species of polypeptide with MW 41×103 and one ssRNA with MW 1.8×106.