Resumo

ALVAREZ-RODRIGUEZ, Brando et al. Characterization of Phytophthora nicotianae causing vinca blight in urban areas and ornamental nurseries in Culiacan, Mexico. Rev. mex. fitopatol [online]. 2016, vol.34, n.3, pp.242-257. ISSN 2007-8080.  https://doi.org/10.18781/r.mex.fit.1605-1.

The aims of this study were to obtain and characterize, by morphological and molecular techniques, Phytophthora isolates associated with blight symptoms on vinca plants in urban areas and nurseries in Culiacan, Mexico, determine the mating types and evaluate the pathogenicity of isolates. Isolates developed white and cottony colonies with coenocytic mycelium on V8 agar; intercalary and terminal chlamydospores (20 μm) and papillate sporangia, round or oval (34.16 μm and 26.35 μm). The isolates were heterothallic: 21 isolates resulted A1 type and 18 isolates were A2 type. A group of representative isolates showed pathogenicity and caused vinca blight incidence between 13 and 66 %. The identity of the isolates was confirmed by analysis of nucleotidic sequences of the ITS region and nuclear genes as elongation factor (TEF-1α) and beta tubulin (β-Tub). The sequences, compared to the NCBI database, showed a high degree of identity with P. nicotianae (ITS, 98-100 %; TEF-1α, 99-100 %; βTub, 98-100 %) and phylogenetically clustered with reference strains. The utilization of specific primers resulted in a positive amplification for the isolates tested. This is one of the few studies on plant diseases affecting ornamental plants in urban areas in Mexico.

Palavras-chave : Oomycetes; ornamental plant diseases; heterothallism.

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