Sequence analysis of minute amounts of viroid RNA using the polymerase chain reaction (PCR). Rapid communication.

The amount of viroid RNA required for sequence analysis can be reduced by five to six orders of magnitude when a modified "polymerase chain reaction" (PCR) is used for the amplification of the reversely transcribed, overlapping viroid cDNAs. By applying this procedure it is possible to establish the molecular structure also of those viroids which are present only in extremely low amounts in various crop plants and ornamentals.