Detection and occurrence of melon yellow spot virus in Ecuador: an emerging threat to cucurbit production in the region

Abstract

More than fifty viruses have been reported in cucurbit crops worldwide. In Ecuador, approximately 3,000 ha of watermelon, melon and cucumbers are cultivated annually, but there have been few studies to identify viruses responsible for epidemics. During this study, sequencing of double-stranded RNA (dsRNA) extracted from watermelon and melon leaves showing virus-like symptoms revealed the presence of Melon yellow spot virus (MYSV, genus Tospovirus) and the partially described Cucumis melo endornavirus (CmEV). Specific primers, designed to detect each virus, showed that MYSV was present in 40, 64 and 67 % of symptomatic watermelon, cucumber and melon samples, respectively. For CmEV, 95 % of both symptomatic and asymptomatic melon plants tested positive. However, the virus was not detected in watermelon or cucumber. Sequence comparisons showed nucleotide identities of 97 % and 94 % for the polymerase and the nucleocapsid protein, respectively, between the Ecuadorean MYSV and the one reported from Japan. To the best of our knowledge, this is the first report of MYSV and CmEV in Ecuador and the Americas.