Endophytic fungal communities in leaves of tropical forest trees: Diversity and distribution patterns

Endophytic fungi cause symptomless infections in healthy tissues of plants. This cryptic guild of fungi is regarded as a benchmark for estimating fungal biodiversity. We studied endophyte distribution, diversity and host recurrence in 24 tree hosts (belonging to 17 plant families) of two dry tropical forests of the Nilgiri Biosphere Reserve. A total of 81 endophyte taxa were isolated from 3600 tissue segments. Fifty-six species were isolated from more than one host. We discerned two groups of fungi in both forests, one group consisting of the ubiquitous forms that dominated the endophyte assemblage of many hosts and the second represented by the less frequent forms. Host density influenced the composition and distribution of endophytes in one of the forests. The existence of ubiquitous forms reduced the diversity of the endophytes in the plant communities. Our results suggest that dry tropical forests are not hyperdiverse with reference to endophytes and that the generalists among endophytes be identified before extrapolating data to calculate global fungal diversity.