Abstract

JIMENEZ, Odaliz; CONTRERAS, Nancy  and  RODRIGUEZ, Carmen. Identificación y caracterización de Pantoea agglomerans aislada en plantas de gloxinia (Gloxinia alba)Identification and characterization of Pantoea agglomerans isolated from Gloxinia alba. Bioagro [online]. 2007, vol.19, n.1, pp.53-57. ISSN 1316-3361.

A humid blight surrounded by a yellow halo was observed in flower and leaf tips of Gloxinia, and when advancing caused necrosis, defoliation and death of the plant. Isolations were made of from this material, resulting in yellow bacteria colonies. For the pathogenicity tests, spray inoculations were made using a bacteria suspension (10⁸ cells·mL^-1) in wounded and non-wounded flowers and leaves, being the former affected more rapidly. Four days later, the symptoms were severe and in time the flowers and leaves became wilted. In the reisolation test, colonies identical to the original were obtained. The isolated bacterium was Gram negative and showed a rod shape through conventional microscope. The colonies were yellow in nutrient agar medium and in YDC. In the medium D₃ of Kado and Heskett, the green coloration changed to red. The pathogen resulted facultative anaerobic, acid reaction in red fenol dextrose agar, tolerant to concentrations of 5% NaCl, negative starch hydrolysis, positive nitrate reduction, positive indol, positive growth in YS medium at 37 ºC, negative oxidase, positive catalasa, positive carbohidrate reduction in sucrose, manose, maltose, arabinose and glucose, and negative in melibiose. The bacteria was identified as Pantoea agglomerans, being considered the first report of this pathogen affecting  Gloxinia alba in Venezuela and at world wide level.

Keywords : Plant pathogen; bacteria; Erwinia; ornamental plants.