A pospiviroid from symptomless portulaca plants closely related to iresine viroid 1

• Portulaca latent viroid (PoLVd) is a potentially new pospiviroid from Portulaca sp.
• The new viroid shows highest sequence identity with iresine viroid 1 (IrVd-1).
• PoLVd should be considered a new species based on its molecular properties.
• Biological differences between PoLVd and IrVd-1 have not yet been found.

In symptomless plants of portulaca a potential new pospiviroid was characterized. Analysis by both double and return PAGE showed the presence of a circular RNA. RT-PCR and sequencing revealed a genome of 351 nt with properties characteristic of members of the genus Pospiviroid and with highest sequence identity (circa 80%) with iresine viroid 1 (IrVd-1). The circular RNA from portulaca was shown to replicate independently in its original host, thus showing that it is indeed a viroid. Based on its molecular characteristics, it should be considered a new species. However, since no biological differences have yet been found with its closest relative IrVd-1, the viroid from portulaca does not fulfil all criteria for species demarcation of the ICTV.