DISTRIBUTION OF VIRUSES IN OLD COMMERCIAL AND ABANDONED ORCHARDS AND WILD APPLE TREES

Abstract

Samples from apple trees in old commercial and abandoned orchards as well as in wild apple trees in the outskirts of Prague in the Czech Republic were surveyed for the presence of Apple mosaic virus (ApMV), Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV) and Apple chlorotic leaf spot virus (ACLSV) using conventional and quantitative RT-PCR. Results revealed that ACLSV was the most frequent virus (70%) in old apple cultivars. ASPV together with ASGV were present in approximately half of the tested trees, and ApMV was found at the lowest frequency. Unexpectedly, the occurrence of ApMV, ASGV and ASPV was confirmed in wild-growing apple trees although the incidence was low. Sequence of the coat protein coding gene from several of these apple virus isolates provided insights into their population structure in Central Bohemia. Together, our molecular findings extend our knowledge on the distribution of apple viruses in populations of old cultivated apple trees in the Czech Republic and provide the first evidence of the presence of ApMV, ASGV and ASPV in wild apple trees. The latter finding raises the question on the origin of viruses in wild apple trees because their spread without human intervention is not known.