The hidden diversity of mangrove endophytic fungi from Tanzania: insights from a preliminary study

Endophytic fungi exhibit a wide distribution across various plant tissues, including mangroves yet their exploration in many regions worldwide remains limited. Consequently, this study presents the first-ever report on the endophytic fungal diversity observed within the mangrove ecosystem of selected coastal areas in Tanzania. A culture-dependent technique was deployed to explore these fungi, followed by morphological and molecular characterization. Using the leaves, stems, and roots of five different mangroves: Avicennia marina, Brugniera gymnorrhiza, Lumnitzera racemosa, Ceriops tagal, and Sonneratia alba we examined how mangrove species and tissue types affected the diversity of endophytic fungi. A total of 34 fungal isolates were collected, and they represented three classes: Sordariomycetes, Dothideomycetes, and Eurotiomycetes. These classes included fifteen genera and seven orders, totaling twenty-five different species. Among the identified genera, Aspergillus emerged as the dominant genus, constituting 26.47% of the collected isolates, followed by Pestalotiopsis at 14.71%. Endophytic fungal diversity in the examined explants was analyzed using Shannon-Weiner (H') and Simpson's (1-D) diversity index. In comparison to other plant tissues, the stem showed a high degree of variety (H' = 2.54). Conversely, compared to other mangrove species, Avicennia marina displayed a higher fungal diversity (H' = 2.46). Notably, this study also reveals the presence of two species, namely Roussoella neopustulans and Spegazzinia bromeliacearum, that had not been previously documented as endophytic fungi within mangroves. The study underscores the diverse and promising potential of mangrove fungal endophytes, highlighting the need for further research and sustainable management in this area.