ACTION OF 3 PLANT-VIRUS INHIBITORS ON POTATO-VIRUS-X

Extracts from Bougainvillea spectabilis, Mirabilis jalapa and Phytolac ca thirsiflora were tested with the aim of studying their action on po tato virus X (PVX) in Gomphrena globosa. The crude and the clarified l eaf extracts induced nearly 100% inhibition. After high speed centrifu gation of the clarified leaf extracts with and without PVX inoculum, t he supernatants and precipitates showed considerable antiviral activit y although precipitates manifested a lower % inhibition. When submitte d to progressive dilutions, the extract-inoculum mixtures induced low values of local lesions in all dilutions. B. spectabilis attained the end point of dilution at 1:2,000, M. jalapa at 1:3,000 and P. thirsifl ora at 1:5,000. Since the controls of the three extracts (virus + buff er) when submitted to different dilutions were not identical, the poss ibility exists of extract translocation from treated leaves. The extra cts may have acted on plant host susceptibility and a temporary connec tion of the inhibitors with the virus is suggested.