Phylogeny, morphology and pathogenicity of fungi of the Cryphonectriaceae family in different hosts

Abstract

The Cryphonectriaceae family accommodates fungal genera that can cause cancer in species of the family Myrtaceae and Melastomataceae worldwide. The genus Chrysoporthe has, so far, covered nine species reported in tropical countries, on the continents of Africa, America and Asia, focusing on species of the family Myrtaceae and Melastomataceae. In Brazil, the species Chrysoporthe cubensis, C. doradensis and C. puriensis occur. These fungal species were detected in forest species of economic value, such as Eucalyptus sp. and native species, such as Tibouchina sp. Recent discoveries have revealed new species within the Cryphonectriaceae family at the level of genera and species causing cancer in Myrtales. The symptoms of cancer disease can cause lesions in the exchange of the plant that reduce its growth, leading to the rupture of the tissues of trunks and branches culminating in its death. The present work was divided into two articles, the first aimed to study the phylogeny and morphology of a new genus in the family Cryphonectriaceae. The isolates of the new genus were obtained from hybrids of Eucalyptus grandis x Eucalyptus urophylla, collected in Tocantins / Brazil, showing symptoms of cancer in the wood and signs of fruiting bodies in the bark of the tree. The fungus was characterized based on its morphology and sequences of the ITS (Internal Transcribed Spacer), β-tubulin and LSU (Large Subunit of rDNA) regions. The isolates showed signs and symptoms characteristic of the Cryphonectriaceae family. Phylogenetic analyzes showed that these isolates found in eucalyptus, obtained separation from other genera already described in Cryphonectriaceae, with high support value for the methods of maximum likelihood, maximum parsimony and Bayesian inference. With the second article, the first report of the fungus C. puriensis in T.mutabilis was described. The isolates were collected at the Serra do Mar in São Luiz do Paraitinga (SP) with signs of fruiting bodies on the tree bark. The fungi isolates from T. mutabilis were identified based on morphological characterization and phylogenetic analysis using the Bayesian Inference and Maximum Parsimony methods of the ITS and β-tubulin regions. The morphology of the isolates was similar to that described for C. puriensis. Phylogenetic trees showed similar topologies and high support for the ITS and β-tubulin regions. The inoculated isolates caused cancer in seven eucalyptus clones and T. mutabilis and T. granulosa seedlings, demonstrating that the fungus is pathogenic for these hosts. The results demonstrate the importance of larger collections in individuals of the order Myrtales in order to study the genetic diversity of fungi of the Cryphonectriaceae family and the need to include these pathogens in programs for the selection of eucalyptus clones resistant to these pathogens.