FIRST REPORT OF PEPINO MOSAIC VIRUS ON TOMATO IN APULIA, ITALY

Abstract

In October 2013, unusual chlorotic patches were observed on the middle leaves of a few tomato plants cv. Lotty grown in a greenhouse located in the countryside of Fasano (Apulia, southern Italy). Younger leaves and fruits were symptomless and no aggravation of symptoms was detected as time went by. Electron microscope observations of leaf dips revealed the presence of filamentous virus particles ca. 520 nm in length. Mechanical inoculations with leaf extracts from symptomatic tomatoes elicited a mosaic reaction in Nicotiana benthamiana, but not in tomato plants cv. UC82, which, however, were systemically infected, as shown by RT-PCR. A RT-PCR product of the expected size (ca. 700 bp) was obtained using the degenerate broad-spectrum potexvirus primers Potex5/Potex1RC (van der Vlugt and Berendsen, 2002). The amplicon was custom sequenced (BMR Genomics, Italy) and the sequence deposited in GenBank under the accession No. KM923762. BLAST alignment showed that the 700 bp amplicon shared 97-99% homology with the RNA-dependent RNA polymerase (RdRp) gene of several isolates of Pepino mosaic virus (PepMV) genotype CH2, 82% homology with the LP and EU genotypes, and 79-80% with the US genotype. A RT-PCR-restriction fragment length polymorphism (RFLP) analysis of the RdRp amplicon with EcoRI and BglII restriction endonucleases confirmed that our isolate, designated PUG1, belongs to the CH2 genotype (Hanssen, 2010). Our observations and assays are consistent with the presence of PepMV in the tomato plants tested, and the fact that PUG1 is a mild isolate of the virus. PepMV has previously been recorded from tomato in three Italian regions, i.e. Sardinia, Sicily and Campania, but this the first report from Apulia.