Potencial biotecnológico dos fungos endofíticos do guaraná (Paullinia cupana var. sorbilis) no controle biológico da antracnose

Abstract

The Amazon has a huge biological diversity, which is little known and consequently little explored, particularly with respect to microorganisms and their interactions with plants in the region. Among the microorganisms of interest are bacteria (including Actinomycetes) and fungi (including yeasts) that inhabit the interior and the surface of the host plants (endophytes and epiphytic microorganisms, respectively). Many of these microorganisms are potentially relevant characteristics as the production of antibiotics, flavorings, colorings, plant growth hormones and useful enzymes, among others. The aim of this study was to isolate, select, characterize and identify endophytic microorganisms present in the leaves, branches and rhizosphere of guarana (Paullinia cupana) as potential biocontrol agents of Colletotrichum. For this study, isolates of Colletotrichum were identified morphologically and molecularly and proven to be causative agents of anthracnose through the pathogenicity test. Then, the direct confrontation of 522 endophytic fungi against the pathogen Colletotrichum resulted in the selection of the following isolates showed significant antagonism rates: Penicillium verruculosum, Penicillium pinophilum, Geotrichum sp, Aspergillus flavus and Schizophyllum commune. Two in vivo experiments were performed in a greenhouse: For the first experiment, we used the five isolates in vivo test against Colletotrichujm gloeosporioides in which the fungi P. verruculosum, P. pinophilum, Geotrichum sp, A. flavus and. S. commune showed significant antagonistic effect on the fungus Colletotrichum gloeosporioides and none of them showed pathogenicity against P. cupana. The second experiment used two isolates of C. gloeosporioides, one in which the occurrence of double-stranded RNA bands (dsRNA) has been observed isolated, and the other without double-stranded RNA. For this experiment, it was found that the foliar lesions were lower in the leaves that were inoculated with the isolated double-stranded RNA, confirming thus a hypovirulent characteristic hipovirulenta isolated. In both experiments, it was observed that the endophytic fungi have the potential to control the pathogen plant pathogens in P. cupana and is promising for use in biocontrol of diseases of this plant.