Pepino mosaic virus and Tomato chlorosis virus causing mixed infection in protected tomato crops in Sicily

Abstract

An unusual virus-like yellow leaf disorder associated with fruit marbling was observed during the winter of 2005 in some greenhouse tomato crops in the province of Ragusa Sicily (Southern Italy). Leaf samples from 250 symptomatic tomato plants were serologically tested by DAS-ELISA technique for 5 viruses: Tomato spotted wilt virus (TSWV), Impatiens necrotic spot virus (INSV), Tobacco mosaic virus (TMV), Cucumber mosaic virus (CMV) and Pepino mosaic virus (PepMV). PepMV was detected in 215 of the samples. The virus was mechanically transmitted to cucumber, wild metel, wild tobacco and ‘Rio Grande’ tomato. The experimental host range of PepMV-Ragusa differed from that of the PepMV found in Sardinia in 2001, which infected ‘Camone’ tomato. By applying RT-PCR to 25 PepMV-infected tomato plants, the expected 844 bp DNA fragment for PepMV and the expected 439 bp DNA fragment for Tomato chlororis virus (ToCV) were obtained from all the samples tested. Sequences of the obtained amplicons were used to study the phylogenetic relationships of the viruses with isolates from other countries. Nucleotide sequence alignments showed that the sequence CP-PepMV-Ragusa (Genbank acc. No. DQ 517884) were 99% homologous with both US2 and Spain-Murcia isolates, while those of ToCV-Ragusa (Genbank acc. No. DQ517885) isolate HSP70, were 99% homologous with the Florida isolate, and 98% with the Lebanon isolate. The results proved that the unusual disorder found in greenhouse tomatoes in Sicily can be associated with infections by PepMV and ToCV, reported for the first time in a mixed infection.