MOLECULAR DETECTION OF A CLOSTEROVIRUS ASSOCIATED WITH APRICOT STEM PITTING IN SOUTHERN ITALY
N. Abou Ghanem-Sabanadzovic, M. Mahboubi, B. Di Terlizzi, S. Sabanadzovic, V. Savino, J.K. Uyemoto, G.P. Martelli
Electrophoretic analysis of cortical and leaf tissue extracts from apricot trees of cv. ‘Tyrinthos’ from Apulia (southern Italy) affected by stem pitting, contained multiple double-stranded RNA (dsRNA) species, the largest with an estimated size of 15 kbp. A segment of 590 nucleotides, showing sequence homology with the HSP70 homologue gene of members of the family Closteroviridae was amplified by RT-PCR from symptomatic trees using degenerated primers designed on the conserved phosphate 1 and 2 motifs of the HSP70 gene sequence. Computer-assisted analysis showed that the 590 nt fragment from Italian apricot trees had 97% sequence homology with Plum bark necrosis stem pittingassociated virus (PBNSPaV), a recently reported closterovirus infecting Black Beaut plum (Prunus salicina) in California. A set of primers that amplified a 290 nt virus-specific fragment was designed and a cRNA probe was generated. This riboprobe and RT-PCR assays with these primers detected PBNSPaV in diseased but not in healthy apricot trees.