A previously undescribed potyvirus isolated and characterized from arborescent Brugmansia.

A suspected virus disease was identified from an arborescent Brugmansia x candida Pers. (syn. Datura candida Pers.) tree. The causal agent was aphid transmissible at low rates. Viral particles were purified from infected tobacco tissue, analyzed, and purified virions were inoculated into healthy tobacco plants to recreate the symptoms. The virions had a mean length of 720-729 nm, and infected cells contained inclusion bodies typical of potyvirus infections. Analysis of infected tissues and purified virions with a panel of potyvirus-specific antibodies confirmed identification as a potyvirus. Viral host range, dilution end point, thermal tolerance and aphid transmission characteristics were examined. The viral genome (9761 nt) is typical of potyviruses, with the closest related potyvirus being pepper mottle virus, at 72 % nt sequence identity. Based on conventions for naming novel potyviruses, the virus was determined to be a member of a previously undescribed species, tentatively named "Brugmansia mosaic virus" (BruMV).

Environment determines fidelity for an RNA virus replicase.

The rate of insertion and deletion mutations of the replicase of Cucumber mosaic virus (CMV) was determined in planta by using a parasitic satellite RNA (satRNA) as a reporter. We found that the CMV replicase had different fidelity in different environments, with important implications in viral disease evolution. Insertions were very rare events, irrespective of the region of the satRNA genome assayed and independent of the hosts tested. On the other hand, deletion events were more frequent but were restricted to a highly structured region of the reporter. Deletion mutation rates were different for the two hosts tested, although the mutation distribution was not influenced by the hosts. Moreover, hot spots with high mutation rates were identified on the satRNA genome.