Detection of cherry leaf roll nepovirus (CLRV) in birch, beech and petunia by immuno-capture RT-PCR using a conserved primer pair

Viruses in woody forest plants are known to be difficult to detect owing to phenolic compounds in plant extracts and an often irregular distribution of the pathogens within the plants. We describe a modified immunocapture reverse transcription polymerase chain reaction (RT-PCR) to detect cherry leaf roll virus (CLRV) in forest trees. The application of a conserved primer pair is shown to be suitable for the detection of different isolates of CLRV from birch from distant forest stands in Germany and also in strains of CLRV from other host plants, including beech, walnut and petunia hybrids. The CLRV isolates and strains could be distinguished by direct sequencing of their PCR products. CLRV was easily detectable throughout the year in tissue of male inflorescences, leaf buds, leaves, single seeds, cortical tissues of young twigs and also in single aphids and bugs (Kleidocerys resedae) collected from a CLRV-infected birch-tree.