Modification of anthracnose severity in açaí seedlings by the endophytic fungus Hypoxylon anthochroum strain 2.4996

Abstract

The cultivation of açai palm, which yields tasteful and nutritional fruits, has been stimulated by the high commercial values of açai pulps; however, the occurrence of anthracnose (a disease caused by the fungus Colletotrichum gloeosporioides) on açaí nursery and orchards has been a challenge for the shift from açaí extractivism to its cultivation. The interaction among endophytic fungi and host can change the plant disease severity, facilitating infection by phytopathogens and increasing its damage to plants. Therefore, this study aimed to investigate the antagonistic activity of five endophytic fungi against C. gloeosporioides, as well as to evaluate the anthracnose severity in açaí seedlings in response to the inoculation of the most promising of the tested endophytic fungus. First, in vitro evaluation showed that most of the fungi were able to grow over C. gloeosporioides mycelia. The endophytic fungi Graphium sp. 2.4765 and Hypoxylon anthochroum 2.4996 recorded the highest rates of growth inhibition, 79.3% and 77.0%, respectively. Because H. anthochroum 2.4996 presented better in vitro growth and spore production, it was chosen for subsequent evaluations. Second, in planta evaluation showed that the inoculation of H. anthochroum 2.4996 in diseased plants enhanced both the necrotic area in leaflets and disease symptoms. Third, comparative analyses based on the cultural, micromorphological and molecular characteristics have shown that such strain is related to H. anthochroum. Overall, this study highlights the complexity of the plant–microbe interactions.