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Ecology and Epidemiology

Comparative Studies on Host Range and Serology of Papaya Ringspot Virus and Watermelon Mosaic Virus 1. S. -D. Yeh, Graduate research assistant, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; D. Gonsalves(2), and R. Provvidenti(3). (2)(3)Associate professor, and senior research associate, respectively, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456. Phytopathology 74:1081-1085. Accepted for publication 6 April 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1081.

A total of nine isolates of papaya ringspot virus (PRV) were obtained from Taiwan, Hawaii, Florida, and Ecuador. The host ranges of these isolates included members of Chenopodiaceae, Cucurbitaceae, and Caricaceae. Variations in symptoms were observed, but there were no significant differences among the host ranges of the isolates. Three species of Cucurbitaceae (Cucumis metuliferus (Acc. 2459), Cucumis anguria var. anguria, and Cucumis anguria var. longipes) were found to be valuable hosts for the propagation of PRV. Three isolates of watermelon mosaic virus 1 (WMV-1), one each from New York, Virginia, and Florida were used for comparison. The major difference between PRV isolates and WMV-1 isolates was that the former infected Carica papaya (papaya) and the latter did not. Cucumis metuliferus (PI 292190), Cucumis melo line B66-5, and Cucumis sativus ' Surinam,' which possess genes resistant to WMV-1, reacted identically to all isolates of WMV-1 and PRV. All the isolates of PRV and WMV-1 tested were serologically indistinguishable as determined by agar immunodiffusion tests with antisera to PRV and WMV-1. The similarities in resistant-susceptible host reaction and in serology strongly indicate that PRV and WMV-1 are very closely related. Our data also indicate that PRV isolates from widely separated geographic regions of the world have very similar biological and serological properties.