Plum Pox Virus Mixed Infection Detected on Apricot in Pakistan

Sharka, caused by Plum pox virus (PPV), is the most detrimental viral disease of stone fruit trees. First reported from Bulgaria in 1917, the virus is now widespread in Europe, the Mediterranean Basin, and Asia Minor and is sporadically present in North and South America. On the basis of molecular and serological properties, six PPV subgroups are recognized, from which PPV-D, PPV-M, and PPV-Rec are the most common (1,2). Several apricot trees (Prunus armeniaca) showing mild, pale green rings and diffuse chlorotic spots on leaves were found in a small orchard in the Baltistan District in northern Pakistan at approximately 2,400 m above sea level. Dried leaf samples from one symptomatic tree randomly selected from the orchard were positive for PPV using double-antibody sandwich enzyme-linked immunosorbent assay with antisera prepared in the laboratory, immunoblot analysis, and reverse transcription-polymerase chain reaction (RT-PCR) targeting the capsid protein (CP) gene using standard procedures (1). To ch...