Fig. 3.
Northern blot hybridization analysis of transgenic Arabidopsis expressing different dimeric (+) viroid RNAs. Viroid-enriched RNA preparations, obtained by chromatography on nonionic cellulose, were fractionated by single denaturing PAGE in duplicated gels and blotted to nylon membranes that were hybridized with 32P-labeled riboprobes for detecting the (+) and (-) strands of CEVd (A and B), HSVd (C and D), and ASBVd (E and F), respectively. Lanes 1, controls of CEVd-infected gynura (A and B), HSVd-infected cucumber (C and D), and ASBVd-infected avocado (E and F); lanes 2, nontransformed Arabidopsis control; lanes 3-5, transgenic Arabidopsis expressing dimeric (+) RNAs of CEVd (A and B), HSVd (C and D), and ASBVd (E and F). Positions of linear RNA markers, with their size in nucleotides, are indicated on the left in A, C, and E. Positions of circular and linear CEVd, HSVd, and ASBVd monomeric RNAs are indicated on the right in A, C, and E, respectively. Both riboprobes for each viroid were equalized in acid-precipitable counts, and the films were exposed for the same time. For facilitating detection of CEVd and HSVd (-) strands, the volume of applied extract was 10-fold higher.