Identification of a new virus disease of snake gourd by host range studies and enzyme linked immunosorbent assay (ELISA)

Abstract

Family Cucurbitaceae crops are mostly prostrate or climbing herbaceous annuals comprising 90 genera and 750 species that are further characterized by commonly having 5- angled stems and coiled tendrils. Cururbita maxima (pumpkin), Trichosanthus cucumerina (snake gourd), Luffa acutangula (loofah), Citrullus lanatus (water melon) and Momordica charantia (bitter gourd) are the most cultivated species of cucurbits in Sri Lanka . Cucurbits are mainly susceptible to five major viruses; Cucumber mosaic virus (CMV), Papaya ring spot virus (PRSV-P), Water melon mosaic virus-1 (WMV-1), Water melon mosaic virus-2 (WMV-2) and Zucchini yellow mosaic virus (ZYMV). PRSV has not been reported in cucurbit crops in Sri Lanka. The snake gourd crops in Ceylon Agro Development Company (Private) Limited (CADC) farm in Sumangalapura, Dambulla showed symptoms similar to PRSV infection. The experiment was conducted to identify this snake gourd virus disease and to study the host range o f the virus using enzyme linked immunosorbent assay (ELISA) and cross inoculation. According to the ELISA test the virus isolate was serologically closely related to PRSV-P. Ratna and Red lady papaya varieties, rnae, cow pea and bean as legumes, cucumber, snake gourd, kekiri, pumkin, ash pumpkin, bottle gourd, ridge gourd as cucurbits, tomato as solanaceous crop,chenopodium and gompinia as Compositae crops were used for host range study and for inoculation study. According to the host range study, the virus was identified as PRSV-W. Snake gourd, pumpkin and ash pumpkin were susceptible to this virus. An inoculation study revealed that Compositae, Legiminosae, Solanaceae and Chenopodiaceae crops were resistant to the virus. Both Ratna and Red lady varieties of papaya were susceptible to the PRSV-P. The snake gourd virus isolate and type ‘P ’ of PRSV can easily be separated using papaya as indicator host.