NEW POTATO SPINDLE TUBER VIROID AND TOMATO LEAF CURL GEMINIVIRUS STRAINS FROM A WILD SOLANUM SP

Three distinct viruslike agents were isolated from a wild, symptomless Solanum sp. suspected of being a natural reservoir of tomato leaf cur l geminivirus. Two of these contained circular DNA genomes of approxim ately 2.7 kb and were identified as geminiviruses. Restriction analysi s and partial sequencing of viral DNA indicated that the two geminivir uses are related to, but distinct from, the Australian strain of tomat o leaf curl virus. These viruses were not mechanically transmissible; however, a mechanically transmissible disease agent was also present, which caused stunting of infected tomato plants followed by shoot elon gation and hairlessness. Analysis of nucleic acids from sap-inoculated tomato plants revealed the presence of a circular RNA, which was isol ated and shown to be the causal agent of the transmissible disease. Th e complete nucleotide sequence of this 356-nucleotide RNA revealed tha t it was a sequence variant of potato spindle tuber viroid.