Characterization of two different apricot latent virus variants associatedwith peach asteroid spot and peach sooty ringspot diseases

Peach asteroid spot (PAS) and peach sooty ringspot (PSRS) are two diseases of stone fruit trees of unknown aetiology. The use of a cRNA probe of the n ewly described Apricot latent virus (ApLV), a tentative member of the Fovea virus genus, indicated the presence of cross-hybridizing agents in PAS isol ate LA2 and in PSRS isolates Caserta 12 and Clava J4. Analysis of dsRNA pat terns revealed in each case the presence of a major dsRNA band of about 9.6 kbp. The purified dsRNAs were used to obtain cDNA clones for isolates LA2 and Caserta 12. Sequence analysis of a 1.1 kbp cDNA clone from isolate LA2 showed very high homology with the known ApLV sequence, indicating that thi s isolate represents a closely related variant of ApLV Sequence analysis of a 3.06 kbp Caserta 12 cDNA clone representing the 3' region of the genome revealed a genomic organization similar to that reported for other members of the Foveavirus genus, including the triple gene block and a large, 43.6 kDa coat protein. Sequence comparison with the CP gene of ApLV, the only se quenced region so far for this virus, showed an overall homology of 78%. Th ese results indicate that the foveavirus represented by the Caserta 12 isol ate of PSRS disease may be regarded as a distant variant of ApLV The presen t results indicate that the viral agents associated with peach asteroid spo t and peach sooty ringspot diseases might be variants of the recently descr ibed ApLV