Indicator plants: Tools for Detecting Papaya Ring Spot Potyvirus and Cucumber Mosaic Cucumovirus

Papaya ring spot potyvirus (PRSV) and Cucumber mosaic cucumovirus (CMV) cause considerable yield losses in important horticultural crops. Therefore, diagnosis of disease at early stage is essential to avoid outbreaks and to control prevalence. In the case of viral diseases, host range studies are still important in diagnosis. Electron microscopy, serological tests and PCR are the most prominent techniques for detecting viruses. However, scientists in many laboratories still rely on biological tests such as inducing symptoms on indicator plants.

In the present study, symptoms were observed on a range of indicator plants three weeks after inoculation. Ten different indicator plant species along with the natural host, Papaya, were inoculated with the PRVS. None of the indicator plants gave clear symptoms except Chenopodium quinoa, which showed local lesions, gave clear symptoms. However, all the inoculated papaya plants exhibited typical PRSV symptoms. Indirect ELISA test was done to check the presence of the virus in those plants, which showed visual symptoms. Eighty percent of papaya plants and 50% of Chenopodium quinoa plants gave positive value in the indirect ELISA test. Similarly, ten different indicator plant species were inoculated with the CMV and five of them gave clear visual symptoms.

However, ELISA test with a monoclonal antibody against CMV produced negative results in some of the indicator plants that gave visual symptoms. Out of ten plant species studied for PRSV, Chenopodium quinoa was shown as only potential indicator plant. For CMV, five potential indicator plants Capsicum annum, Datura stramonium, Solanum melongena, Chenopodium quinoa and Gomphrena globosa were identified.

Keywords: Diagnostic Code; Papaya Ring Spot; Cucumber Mosaic; Chenopodium quinoa

DOI: 10.4038/jfa.v1i2.1800

Journal of Food and Agriculture Vol.1(2) 2008 pp.64-69