COMUNIDADE DE FUNGOS ENDOFÍTICOS ASSOCIADOS Á Araucaria angustifolia (Bertol.) Kuntze

Abstract

Araucaria angustifolia (Bertol.) Kuntze is a gymnosperm icon of one of the Atlantic Forest's phytophysiognomies, the Araucaria Forest. Due to logging and deforestation, this tree is threatened with extinction. Endophytic fungi play remarkable ecological roles in the environment and are sources of bioactive compounds, thus having several industrial applications. Since studies with endophytic fungi related to Araucaria are scarce, investigating these microorganisms is essential for the preservation of this valuable plant species. Thus, the objective of the present work was to characterize the community of cultivable endophytic fungi associated with A. angustifolia and to evaluate their potential for use as biocontrol agents. Morphologically distinct isolates had the ITS region of the rDNA sequenced in order to enable their molecular identification. Phylogeny studies were performed using Bayesian Inference, Maximum Parsimony and Maximum Likelihood. In addition, the dual culture test was conducted to verify the potential of endophytes to control the growth of phytopathogens Colletotrichum gloeosporioides, Elsinoë ampelina and Phytophthora infestans. In total, 102 fungi were isolated from 90 fragments from five individuals of A. angustifolia collected in a remnant of Araucaria Forest, with 61 distinct morphotypes being recognized. Only 37 strains from the endophytic community could be identified using the methodology employed, all belonging to the phylum Ascomycota and to the genera Annulohypoxylon, Aspergillus, Colletotrichum, Coniochaeta, Diaphorte, Fimetariella, Fusarium, Hypoxylon, Mycoleptodiscus, Muyocopron, Neofusicoccum, Neopestalotiopsis, Pestalotiopsis, Phyllosticta, Phomopsis, Preussia, Trichoderma and Xylaria. Fungi of the class Sordariomycetes and of the genus Xylaria comprised the largest number of species found. The strains of endophytic fungi tested were successful in inhibiting the development of phytopathogens, being observed as mechanisms of antagonism to competition and mycoparasitism. The best inhibitory fungi were Aspergillus flavus (W44), Trichoderma koningiopsis (W26), A. fumigatus (W12) and Pestalotiopsis sp. 2 (W24), which were subjected to the activity test of volatile organic compounds (VOCs) against the same phytopathogens. As a result, there was a high inhibition of the growth of plant pathogens. It is concluded that the Araucaria houses a large number of species of endophytic fungi, many of which can be explored biotechnologically, as agents of biocontrol. These results show the importance of studying the microbiota of Neotropical forests, especially that of threatened areas, since the fragmentation of habitats can lead to the loss of important biological resources, as revealed in the present study.