(257) Pepino Mosaic Virus: Variability in U.S. Isolates

Abstract

<jats:p>Pepino mosaic virus (PepMV) was first found in pepino (<jats:italic>Solanum muricatum</jats:italic>) growing in coastal Peru in 1974 and described in 1980; it reappeared in protected tomato (<jats:italic>Lycopersiconesculentum</jats:italic>) in the Netherlands in 1999. Since then, it has been reported to occur in tomato in several countries including Austria, Belgium, Canada, France, Germany, Italy, Peru, Spain and the Canary Islands, the United Kingdom, and in 11 states within the United States. Three strains of PepMV found in the United States have been cloned and sequenced. Full-length genomic sequences were obtained for two strains, PepMV-US1 and PepMV-US2, from co-infected tomato plant samples from Arizona. The 3'-end sequence of PepMV-US3 came from infected tomato fruits from Maryland. The genome organization, motifs and domains typical of the genus <jats:italic>Potexvirus</jats:italic>, and of other PepMV isolates, were found in full-length sequences of both US1 and US2 isolates. Direct comparison of US1 and US2 at the nucleotide level revealed an 86.3% identity; whereas, when individually compared to the French and Spanish isolates, which share ∼99% identity at the nucleotide level, US1 and US2 had 82% and 79% identities to each, respectively. Pair-wise gene-for-gene comparisons between United States and European isolates revealed a similar trend. While unique, US1 is more closely related to the previously reported European isolates than is US2. The CP of US3 is nearly identical to the European isolates at the amino acid level. None of 18 tomato germplasm accessions or 10 cultivars were resistant to mechanical inoculation with US3; in contrast, no infection was detected in nine pepper cultivars or four germplasm accessions. Plants grown from seeds of infected tomato fruits did not test positive for PepMV.</jats:p>