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First Report of Xylella fastidiosa on Catharanthus roseus in Brazil

In 1998, plants of periwinkle (Catharanthus roseus L.) showing small leaves, short internodes, and dieback symptoms were observed in a garden at the Instituto Agronomico do Parana (IAPAR), Londrina, PR, Brazil. Stems of these plants were cut into short sections and the sap extracted from the tissue by squeezing with pliers. The sap was blotted onto a glass slide and examined for the presence of bacteria by light microscopy (×400). Microscopy observations revealed the presence of a large number of slender, rod-shaped bacterial cells. The bacteria present in the stems of periwinkle were isolated on buffered cysteine-yeast extract (BCYE) and periwinkle wilt (PW) agar media. Stems were disinfected in 70% alcohol and cut into short sections, and the sap extracted as described above. The sap was blotted directly onto the media and the plates were incubated at 28°C. Typical colonies of Xylella fastidiosa were observed 10 days after isolation on both media. Indirect immunofluorescence tests with antibody specific to X. fastidiosa and anti-IgG conjugated with tetrametylrhodamine isothiocyanate (TRITC) were carried out with xylem sap of periwinkle stem and the isolated bacteria. In both cases, immunofluorescence tests were positive for X. fastidiosa. These results confirm that periwinkle plants were infected with X. fastidiosa. This is the first report of the association of X. fastidiosa with periwinkle plants in Brazil. However, the symptoms observed for the X. fastidiosa-infected periwinkle plants differed from those described previously in the U.S. (1): those symptoms consisted of marginal chlorosis and occasional vein clearing of leaves and wilting of the plants.

Reference: (1) R. E. McCoy et al. Plant Dis. Rep. 62:1022, 1978.