Diversidade e caracterização morfológica de fungos endófitos isolados de Coccoloba latifolia Lam. (Polygonaceae)

Abstract

Coccoloba latifolia is a native species from Brazil and can also be found in other South American countries. Several studies demonstrated that species of this genus can produce biological compounds, as antimicrobials. C. latifolia is found in different phytogeographic domains and may be a key species for reforestation and recovery of biomes, as the Atlantic Forest. Endophytes are organisms that develop within the plant tissues without causing harm to the host. This endophyte-plant association results in a delicate balance, leading to the production of secondary metabolites and benefiting the plant with improved nutrition and resistance to pathogens. The knowledge about the composition of these assemblages of endophytic organisms is also important to elucidate their effect on plant physiology. This study aimed to characterize morphologically and to group the 90 endophytic fungi isolated from C. latifolia into morphotypes. To carry out the project, the isolated fungi were reactivated and cultured in a working collection. All the endophytes were transferred from the working collection to Petri dishes with PDA medium and subjected to incubation conditions of 25 °C, 59% humidity, and 12h photoperiod. Cultural characteristics such as colony color, texture, edge shape, effect on the culture medium, and mycelial growth rate were assessed, as well as micromorphological characteristics such as mycelium type, presence of septation, and general spore characteristics. Furthermore, the distribution of endophytes in the quadrants of the leaf surface of C. latifolia was mapped, which led to the finding that the colonization by endophytes occurred homogeneously throughout the leaf. The morphological characterization of the endophytes confirmed the probable presence of zygomycetes and or oomycetes and fungi of the phyla Ascomycota and or Basidiomycota. Only 25.5% of the endophytes sporulated on PDA medium. Other media and conditions should be tested in future studies to induce the sporulation of the other isolates. In this study, 29 morphotypes were identified among the analyzed fungi, confirming the diversity of endophytes present in C. latifolia. Understanding this morphological variety is useful for further studies of identification of the isolates and a better understanding of how these endophytes interact with C. latifolia throughout the plant's life cycle and seasonal changes in the environment.