Genetic characterization of Pepino mosaic virus isolates from Belgian greenhouse tomatoes reveals genetic recombination

Abstract

Over a period of a few years, Pepino mosaic virus (PepMV) has become one of the most important viral diseases in tomato production worldwide. Infection by PepMV can cause a broad range of symptoms on tomato plants, often leading to significant financial losses. At present, five PepMV genotypes (EU, LP, CH2, US1 and US2) have been described, three of which (EU, LP and US2) have been reported in Europe. Thus far, no correlation has been found between different PepMV genotypes and the symptoms expressed in infected plants. In this paper, the genetic diversity of the PepMV population in Belgian greenhouses is studied and related to symptom development in tomato crops. A novel assay based on restriction fragment length polymorphism (RFLP) was developed to discriminate between the different PepMV genotypes. Both RFLP and sequence analysis revealed the occurrence of two genotypes, the EU genotype and the CH2 genotype, within tomato production in Belgium. Whereas no differences were observed in symptom expression between plants infected by one of the two genotypes, co-infection with both genotypes resulted in more severe PepMV symptoms. Furthermore, our study revealed that PepMV recombinants frequently occur in mixed infections under natural conditions. This may possibly result in the generation of viral variants with increased aggressiveness.

Differential Tomato Transcriptomic Responses Induced by Pepino Mosaic Virus Isolates with Differential Aggressiveness

“…One of the most damaging effects of PepMV is the so-called fruit marbling, which is likely due to irregular distribution of lycopene, the major red pigment in tomato fruit (Hanssen et al, 2008). To investigate whether PepMV affects pigment production in tomato seedlings, we studied the expression of genes that encode enzymes of the phenylpropanoid/flavonoid and carotenoid (lycopene) biosynthetic pathways (P , 0.05; Fig.…”

“…Symptoms were scored from 0 (no symptoms) to 3 (severe symptoms; Fig. 1B; Hanssen et al, 2008) and statistically analyzed by one-way ANOVA and posthoc Bonferroni tests using SPSS software (version 10.0; SPSS, Inc.).…”

“…Currently, four PepMV genotypes are distinguished: the Peruvian genotype (LP), which was first isolated from Solanum peruvianum and is similar to the original pepino (S. muricatum) isolate (Ló pez et al, 2005;Pagán et al, 2006); the European tomato genotype (EU), which was first reported in greenhouse tomato production in Europe (Mumford and Metcalfe, 2001;Aguilar et al, 2002;Cotillon et al, 2002;Verhoeven et al, 2003;Pagán et al, 2006); the CH2 genotype, which was first isolated from tomato seeds from Chile (Ling, 2007); and the US1 genotype, which was first described in the United States (Maroon-Lango et al, 2005). In recent years, the CH2 genotype has largely replaced the EU genotype in commercial tomato production in several European countries (Hanssen et al, 2008;Gó mez et al, 2009). Two Belgian CH2 PepMV isolates have recently been characterized in detail and were designated mild (isolate 1906, further referred to as the mild CH2 isolate) and aggressive (isolate PCH 06/104, further referred to as the aggressive CH2 isolate) based on symptom expression in naturally infected commercial greenhouse tomatoes and in subsequent greenhouse trials (Hanssen et al, 2009(Hanssen et al, , 2010a.…”

Epidemiología y variabilidad patogénica del virus del mosaico del pepino dulce (Pepino mosaic virus). Nuevas enfermedades asociadas a su presencia (torrao o cribado)

“…Figura 1.14. Análisis filogenético de virus relacionados con el ToTV basados en el alineamiento de la región entre el motivo CG de la proteasa y el GDD de la RdRp.…………………………………60 Phylogenetic analysis of the CP nucleotide sequence of the CH1/US1 isolates not determined by RFLP-PCR method described by Hanssen et al (2008).…………………………………………...102 .3. Molecular analysis of water samples collected from the drainage water of the acquisition-source plants (P 0 ) processed as described in Figure 5.2.…”

“…Porcentaje de identidad de las secuencias de aminoácidos de las diferentes zonas del genoma de ToMarV comparadas con el aislado tipo de ToTV y el aislado polaco Wal03 de ToTV, y el aislado parcialmente secuenciado de ToANV VE434………………………………………..67 Table 3.3. Comparative analysis for the presence of PepMV performed by DAS-ELISA, Molecular Hybridization (MH), multiplex RT-PCR with SacI restriction (RT-PCR-SacI) and RFLP-PCR method described by Hanssen et al (2008) (RT-PCR-Hanssen) to previously described PepMV isolates and field tomato samples……………………………………………..96 Table 4.1. Specific primers of each of three fragments which present 15-bp overlap at the 5' prime end with the adjacent fragment to be joined………………………………………………118 Table 4.2.…”