Single-stranded DNA genome in a whitefly-transmitted plant virus.

Bean golden yellow mosaic virus (GYMV) DNA sedimented in sucrose density gradients and in an analytical ultracentrifuge as a single component. Values of s(20,w) which depended upon ionic strength (i) and pH, were 16.0 (pH = 7.0, i = 0.1); 16.3 (pH = 7.0, i = 1.0); 9.0 (pH = 13, i = 0.1); and 12.0 (0.1 N NaOH, i = 1.0). GYMV-DNA banded in CsCl as a single component with a buoyant density of 1.7170 g/ml and exhibited hyperchromicity when heated between 20 and 70 degrees . Hyperchromicity and a shift in the ultraviolet light absorption maximum were observed when the DNA was treated with formaldehyde (1.8%) at room temperature. Nuclease sensitivity tests showed that the DNA was susceptible to hydrolysis by DNase I and nuclease S1 (specific for single-stranded DNA) but not to hydrolysis by RNase A or by 0.3 N NaOH. Molecular weight values calculated from sedimentation velocity and CsCl equilibrium data were in the range of 0.66 to 0.95 x 10(6) daltons GYMV thus contains DNA with the properties of a predominantly single-stranded molecule and represents the first reported single-stranded DNA virus from plants.