Biological and molecular characterization of Tunisian isolates of Potato leafroll virus

Nine Tunisian isolates of Potato leafroll virus (PLRV) were collected from potato plants (cv Spunta) with similar secondary leafroll symptoms. These PLRV isolates were readily transmitted by Myzus persicae (Sulzer) from potato plants to Physalis foridana test plants inducing symptoms of differing severities. In order to investigate the genetic variability between the PLRV isolates, the ORFO regions of the Tunisian PLRV isolates were sequenced and compared with that of a French isolate (Fr5) that induces mild symptoms and 24 ORFO PLRV sequences available in Genbank. The Tunisian isolate;; could be classified in two of the three groupings of the phylogenetic tree obtained. A tentative correlation b, tween symptom expression in P. foridana and specific changes in the ORFO sequences is discussed.