Properties, Diagnosis and Management of Cucumber green mottle mosaic virus

Abstract

Cucumber green mottle mosaic virus (CGMMV), a species under the genus Tobamovirus, is an important viral pathogen affecting cucurbit crops in Asia and Europe. The virion is rod shaped particle of 300 × 15 nm containing positive sense ssRNA of 6.4 kb as its genome. No insect vector is known to transmit the virus in a specific manner. The virus is highly stable, contagious and sap transmissible. Several isolates have been described from different countries in Eurasian regions infecting important cucurbits such as bottle gourd (Lagenaria siceraria), cucumber (Cucumis sativus), gherkin (Cucumis anguria), muskmelon (Cucumis melo) and watermelon (Citrullus vulgaris). Symptomatology of the virus is characterized by systemic green mottle mosaic on foliage. Some of the isolates induce serious fruit symptoms such as pulp deterioration (‘blood flesh’ disease) in watermelon. The complete genome of CGMMV is composed of 6424 nucleotides containing four open reading frames encoding replicase proteins, movement protein and coat protein. The CGMMV isolates form a distinct evolutionary clade separated from the other cucurbit-infecting tobamovirus species. Several sensitive methods are available for reliable diagnosis of CGMMV of which ELISA and RT-PCR are commonly used. Immunofilter paper assay and bioelectric recognition assay have been shown for rapid test of CGMMV. Control of CGMMV is difficult as commercial cultivars are susceptible. Limited source of resistance is known in muskmelon and wild Cucumis spp. The transgenic approach holds a greater potential in developing resistant varieties against CGMMV in any cucurbit.