CALADIUM VIRUS X A NEW POTEXVIRUS FROM CALADIUM BICOLOR ARACEAE
E.B. Rivas, L.M.L. Duarte, M.A.V. Alexandre, S.R. Galleti, R. Harakava, F.M.C. Fernandes
An elongated virus with particles measuring 460 nm in length and tentatively named Caladium virus X (CalVX) was isolated from Caladium bicolor (fam. Araceae) co-infected with Dasheen mosaic virus. The effect of this double infection was to induce chlorotic and necrotic spots and rings. CalVX was easily transmitted by mechanical inoculation but not via seeds or by aphids. The only systemic experimental hosts detected were Nicotiana benthamiana and some araceous species. There were no positive reactions in serological tests using antisera to 17 potexviruses. CalVX capsid protein has a Mr of 26,000. Electron microscopy of infected cells revealed aggregates of virus-like particles in the cytoplasm, and electron- dense crystalline inclusions in the cytoplasm and nucleus. Comparison of the sequence of 740 nucleotides encoding the putative C-terminal region of the replicase showed that CalVX was most similar (65.8% identity) to Cymbidium mosaic virus and phylogenetic analysis supported its classification in the genus Potexvirus. This is the first report of a natural infection of araceous plants by a potexvirus.