Molecular and biological characterization of pepino mosaic virus isolates occurring in the main tomato-producing areas in Mexico

Abstract

Pepino mosaic virus (PepMV) has caused major epidemics in tomatoes (Solanum lycopersicum L.) worldwide. Five genotypes have been identified: Peruvian (LP), European (EU), American (US1), Chilean (CH2), and Southern Peruvian (PES). The aim of this study was to determine the current distribution of PepMV in the main tomato-producing areas of Mexico, as well as to identify the predominant genotypes and their biological behavior in alternative hosts and indicator species. A total of 77 samples of tomato plants showing PepMV symptoms-like with leaf mottling, mosaic, and chlorosis symptoms, as well as marbled fruit, were analyzed by multiplex reverse transcription PCR (RT-PCR). Sequencing data confirmed the identification of PepMV genotypes in 15 samples from six states. Six samples with single CH2 genotype infection, two with LP genotype, two with EU genotype, and five LP + CH2 co-infections were detected. Moreover, a high prevalence of ToBRFV was found, either in single infection or in co-infection with PepMV. Five PepMV sources (three CH2, one EU, and one with LP + CH2 co-infection) were used in the biological indexing. All isolates induced systemic infection in Solanum lycopersicum, Datura stramonium, Nicotiana occidentalis, and Solanum melongena. In tomato, CH2 isolates induced mild mosaics and chlorosis, whereas the EU isolate caused chlorotic mosaics typical of PepMV. In D. stramonium and S. melongena, chlorosis, interveinal yellowing, and mosaics were observed. Nicotiana occidentalis showed symptoms with all isolates, particularly with the CH2-MXM01 isolate, which caused necrotic lesions. Overall, PepMV is present in at least six states in Mexico, with the CH2 genotype and mixed LP + CH2 infection prevailing. US1 and PES genotypes were not detected. Interestingly, an EU isolate was characterized as an aggressive variant, causing mosaics and severe chlorosis.