Detection of complementary RNA intermediates of viroid replication by Northern blot hybridization

Abstract

Molecular hybridization by the Northern blot technique in combination with 125I-labeled PSTV [potato spindle tuber viroid] (+) RNA and 32P-labeled PSTV cDNA as probes was applied to detect viroid-specific sequences in healthy and viroid (PSTV)-infected tomato plants. Conditions are described which allow differentiation of (+) and (-) viroid sequences on the basis of the different thermostabilities of the corresponding hybrid molecules. No viroid-specific DNA sequences were detected by this approach. Viroid replication apparently proceeds via complementary RNA intermediates. Of the 7 (-) RNA species found, 6 are apparently larger than the circular viroid (+) RNA and 1 is about the same size as the linear (+) RNA molecule.