ABSTRACT
In 2016, four isolates of Phytophthora oomycete were obtained from samples of plane trees (Platanus acerifolia) in the region of Curitiba, Paraná State (Brazil). The obtained isolates were characterized by morphological and molecular analyzes for specific identification. The mycelial growth of isolates at eight temperatures was evaluated, as well as the formation and the dimensions of sexual and asexual structures, while molecular analysis was performed based on the ITS region of the DNA. Pathogenicity test was also carried out for araucaria and plane seedlings and avocado fruits. The isolates presented optimum mycelial growth in the range of 20-28°C and no mycelial growth occurred at 8 and 36 °C. The colonies of the four isolates were classified as cotton-like, presenting mycelium of low-density. The four isolates produced persistent sporangia, predominantly ellipsoid, with no papillae and a mean of 32.5 x 24.2 µm. Formation of globose and terminal chlamydospores with an average diameter of 38.4 µm was observed. All isolates were heterothallic and of the A2 type of compatibility, presenting oospores with amphygenous antheridia and measuring on average 30 µm. Molecular analysis showed 99% similarity between one of the plane tree isolates and the sequences available for Phytophthora cinnamomi in Phytophthora-ID and GenBank. Based on these characters, plane tree isolates were identified as Phytophthora cinnamomi Rands. This is the first report of this pathogen causing the death of plane trees in Brazil.
Keywords
Taxonomy; Oomycete; Disease; Platanus; ITS
