PCR-detection of apple stem pitting virus from pome fruit hosts and sequence variability among viral isolates

A relatively simple and rapid PCR assay has been developed for the detection of apple stem pitting virus (ASPV) from apples and its pear strain known as pear vein yellows virus (PVYV), from pears. The assay allows accurate diagnosis of ASPV and PVYV from leaf, bark and bud tissues of stem pitting or pear vein yellows diseased apple and pear trees, respectively. Nucleotide sequences of the cloned PCR products, derived from different ASPV isolates, have been obtained and analyzed; inserts were used to generate ASPV-and PVYV-specific DIG-labeled cRNA probes. Sequencing and hybridization analyses revealed a potentially high level of molecular variability among the isolates of the virus.