ANTISENSE DNA INHIBITS INFECTION OF POTATO SPINDLE TUBER VIROID

The effect of oligodeoxyribonucleotides complementary to the region of the so-called pathogenicity domain (nucleotides 42-78) of the upper R NA strand of potato spindle tuber viroid (PSTVd) (severe) on viroid in fection was investigated. The oligonucleotides were allowed to form hy brids with PSTVd in the infection mixtures before inoculation. Infecti vity tests were performed using intact plants and plant protoplasts. I t was found that the DNA oligonucleotides caused significant reduction of viroid infection at plant and single cell levels. The 200-fold mol ar excess of antisense DNA over viroid RNA is usually sufficient for t he complete blocking of viroid infection. The inhibitory effect is str ongly sequence specific. Inhibition by corresponding antisense RNA was much less efficient than that caused by antisense DNA.