Phylogeny, morphology and pathogenicity of Neopestalotiopsisspp. and Quambalaria eucalypti on eucalyptus sp.

Abstract

Species of Neopestalotiopsis and Quambalaria sp. are phytopathogenic and cause diseases in several harboures. In Brazil, although relatively frequent in nurseries producing seedlings, Neopestalotiopsis hasn’t identified at the species and Quambalaria level so far not reported under field conditions. In view of the importance of these diseases and the little knowledge available about these patossystems, it was sought to characterize molecular and morphologically as well as to prove the pathogenicity of the disease. In the first study, the isolates were submitted to multilocus analysis using two genetic regions β -tubulin (TUB) and elongation factor (TEF). The analysis of the sequences of genomic regions confirmed the presence of Neopestalotiopsis australis, N. rosae as the first report and the occurrence of a new species as a pathogen in Eucalyptus sp., Brazil. The morphological characterization allowed the identification of N. australis and N. rosae isolates, mainly based on differences in the size and shape of the conidia. Pathogenicity tests showed that the isolates were pathogenic for eucalyptus clones. The results obtained may contribute to the knowledge of the genus Neopestalotiopsis causing diseases in woody plants. In addition, this was the first report of the species Neopestalotiopsis australis, N. rosae as pathogens in Eucalyptus sp. in Brazil. In the second study sequences of five isolates obtained from leaves and cankers were compared to 21 sequences including the outgroup deposited at Genbank. The isolates were submitted to multilocus analysis using the ITS and LSU regions. The phylogenetic analysis of Maximum Parsimony and Bayesian Inference of combined sequences of the two studied regions grouped the isolates evaluated in the clade of Q. eucalypti and the morphological characteristics were similar to those described in the literature. The pathogenicity was confirmed, and the pathogen was again isolated from the inoculated plants confirming its morphological characteristics fulfilling Koch's postulates. This is the first report of Q. eucalypti causing leaf spot and cancer in eucalyptus under field conditions in Brazil. These results may contribute to the knowledge of isolates of Q. eucalypti that occur in Brazil under field conditions and establish protocols to select materials resistant to the pathogen.