Molecular characterisation of the full-length genome of olive latent virus 1 isolated from tomato.

Olive latent virus 1 (OLV-1) is a species of the Necrovirus genus. So far, it has been reported to infect olive, citrus tree and tulip. Here, we determined and analysed the complete genomic sequence of an isolate designated as CM1, which was collected from tomato plant in the Wielkopolska region of Poland and represents the prevalent isolate of OLV-1. The CM1 genome consists of monopartite single-stranded positive-sense RNA genome sized 3,699 nt with five open reading frames (ORFs) and small inter-cistronic regions. ORF1 encodes a polypeptide with a molecular weight of 23 kDa and the read-through (RT) of its amber stop codon results in ORF1 RT that encodes the virus RNA-dependent RNA polymerase. ORF2 and ORF3 encode two peptides, with 8 kDa and 6 kDa, respectively, which appear to be involved in cell-to-cell movement. ORF4 is located in the 3' terminal and encodes a protein with 30 kDa identified as the viral coat protein (CP). The differences in CP region of four OLV-1 isolates whose sequences have been deposited in GenBank were observed. Nucleotide sequence identities of the CP of tomato CM1 isolate with those of olive, citrus and tulip isolates were 91.8%, 89.5% and 92.5%, respectively. In contrast to other OLV-1 isolates, CM1 induced necrotic spots on tomato plants and elicited necrotic local lesions on Nicotiana benthamiana, followed by systemic infection. This is the third complete genomic sequence of OLV-1 reported and the first one from tomato.