Abstract

BERNAL LUGO, Irma et al. Identificación del agente patógeno del cancro del eucalipto en plantaciones del Sureste de México. Rev. Cien. For. Mex [online]. 2009, vol.34, n.105, pp.17-35. ISSN 1405-3586.

In the Southeast of Mexico, there are marketable plantations of different species of Eucalyptus where canker has been reported. The objective of this study was to provide the morphological and molecular identification of the species of eucalyptus canker causal agent in these plantations. Samples of infected bark, branches and new shoots were obtained from different parental sources growing in Oaxaca and Chiapas. The samples were incubated under the right temperature and humidity for the development of reproductive bodies. The pathogen agent was isolated and purified from in vitro cultures of mycelium colonies developed in the canker. The aspect, color, size and morphological characteristics of the reproductive structures were similar to those of Chrysoporthe cubensis. Nevertheless two types of reproductive structures were found in the field and laboratory samples, and it was necessary to verify if both belonged one kind of morphia. To precisely define to which species belonged the morphia, it was carried out a molecular analysis of the reproductive structures. The comparison of nucleotide sequences in the intergenic region of ribosomal genes of these structures, showed a similarity over 97% and when compared to the correspondent genes reported in the gene bank NCBI, pointed out that is only one pathogenic agent whose identity is Ch. cubensis. This pathogen presents dimorphism in this region, such characteristic could make the fungus more aggressive.

Keywords : Pathogenic agent; eucalyptus canker; Chrysoporthe cubensis; morfism; nucleotides; ITS ribosomal sequences.

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