Southern blot detection of CLCuMV in inoculated Nicotiana plants. The DNA samples loaded on the gel were extracted from leaves of plants (as indicated above each well) inoculated with CLCuMV. The leaves sampled were developing at the time of, or developed after, inoculation and were sampled at 25 dpi. An approximately equal amount of DNA (10 μg) was loaded in each case. The blot was probed with a DIG-labeled CLCuMV fragment. The positions of replicative forms of viral DNA are indicated as open circular (oc), linear (lin), super coiled (sc) and single stranded (ss). A photograph of the genomic DNA bands on the ethidium bromide stained agarose gel to confirm equal loading is shown at the base.