The age of lima bean leaves influences the richness and diversity of the endophytic fungal community, but not the antagonistic effect of endophytes against Colletotrichum lindemuthianum

Phaseolus lunatus (lima bean) has been a model organism to understand direct and indirect defenses against herbivores. We investigated the identity and diversity of endophytic fungi associated with young, mature and old leaves of lima bean in its natural environment. We recovered 758 isolates that were identified and classified in 142 fungal species from 66 genera, with Curvularia, Fusarium, Phomopsis, Alternaria and Colletotrichum being the most abundant and diverse Ascomycota genera. Our data revealed that species richness and diversity increased with leaf age, this factor being also important for the structure of the endophytic community. The occurrence patterns of fungal species was highly heterogeneous among leaves, and only fourteen species were recovered from all three foliar ages investigated. In vitro dual assays between endophytes and the plant pathogen Colletotrichum lindemuthianum revealed that most endophytes tested can inhibit the growth of this pathogen, suggesting their potential as biocontrol agents.