molecular and biological characterization of the iranian isolate of the australian grapevine viroid

australian grapevine viroid (agvd), an apscaviroid of the family pospiviroidae, was recently identified in vineyards of southern iran. it had a relatively wide host range and caused stunting, leaf deformation, mottling and vein clearing in experimental hosts upon mechanical inoculation of nucleic acid extracts or agroinfiltration of the viroid infectious cloned dna. predicted secondary structure of the agvd-ir showed a difference from the predicted structure of the type isolate in the viroid pathogenicity domain. mutational analyses showed sequence changes introduced into that domain of the agvd-ir clone decreased the viroid’s replication efficiency in planta but did not show any effects on its movement.