Fungos endofíticos de cafeeiro produtores de compostos orgânicos voláteis e enzimas extracelulares

Abstract

Endophytic microorganisms inhabit the interior of shoot, stems, leaves and roots, without causing harm to their hosts. The interactions of endophytes with their host plants are beneficial and can be related to plant health, controlling the growth of pathogens, nematodes, insects and other organisms. The objectives of this study were to identify endophytic fungi isolated from Coffea arabica producers of volatile organic compounds (VOCs), evaluate the effect of VOCs produced by endophytic fungi on the growth of Rhizoctonia solani, Fusarium oxysporum, Phoma sp., Botrytis cinerea, Fusarium solani, Fusarium verticillioides, Cercospora coffeicola, Aspergillus ochraceus and Pestalotia longisetula, select endophytic fungi with potential for biological control of A. ochraceus inoculated in coffee beans and F. verticillioides inoculated in corn seeds, identify VOCs produced by the endophytic fungus Acremonium sp. (C19) using gas chromatography mass spectrometry (GC- MS) and to assess production of extracellular enzymes. Twelve endophytic fungi were identified as Muscodor spp. (9) Simplicillium sp. (2) and Acremonium sp. (1). The volatiles produced by these fungi inhibited the growth of different phytopathogenic fungi with different efficiencies. Muscodor coffeanum (COAD 1842) showed fungicidal effect against A. ochraceus in coffee beans. The growth of F. verticillioides was inhibited by six endophytic fungi, Muscodor coffeanum (1842, 1899, 1900), M. vitigenus (C20) and Simplicillium sp. (C18). Regarding the VOCs produced by Acremonium sp. (C19), a significant reduction was found in the growth of pathogenic fungi, however, the fungus A. ochraceus and F.oxysporum were less susceptible to VOCs. The Acremonium VOCs profile was investigated using the SPME/GC-MS headspace technique and found compounds belonging to different chemical classes. For enzyme production, all fungi were producers of cellulase and pectinase enzymes, 11 produced lipase, 9 produced phytase and protease and 4 produced amylase. The specific activity of endo-β 1.4 glucanase and exo-β 1.4 glucanase were detected for 12 and 10 endophytic fungi respectively. This study demonstrates that the endophytic fungi of Coffea arabica are promising sources of bioactive metabolites.