Characteristics of PSTVd

Viroid plant diseases are similar to virus diseases. Today at least 30 such diseases are known. Potato spindel tuber viroid (PSTVd), causing spindle-shaped potato tubers, was the first described viroid. It was discovered by Diener in 1971 in the northern part of USA and in Canada, where it still causes significant damage to production.

Viroids are smaller than viruses and may therefore not be seen even by means of electronic microscopy. They are parasites, living exclusively in plant cells. PSTVd is a typical viroid, which are significant for their accumulating inside a cell in the nucleus and along cytoplasmatic membrane. First diagnosticts was unreliable and possible only on the basis of symptoms, chemical analysis of secondary metabolites and tests on test plants. Today, many molecular methods for determination of viroid RNA are available.