Endophytic fungi from seagrasses have been relatively understudied as compared to other groups of marine and terrestrial plants. Therefore, this study aimed to determine diversity and distribution of endophytic fungi from four commonly found seagrasses: Enhalus acoroides, Thalassia hemprichii, Cymodocea serrulata and Halophila ovalis from Thailand. A total of 208 endophytic fungi were obtained; 48 isolates from E. acoroides 79 from T. hemprichii, 69 from H. ovalis and12 isolates from C. serrulata. Most endophytic fungi were obtained from the leaf segments (95.19%) with only 2.88% from root and 1.92% from rhizome segments. The overall isolation rate was 2.51%. Fungal endophytes were identified by morphological characteristics and molecular techniques based on the ribosomal DNA-Internal Transcribed Spacers (ITS), large subunit (LSU) and small subunit (SSU) analyses. One isolate was identified as Pichia sp. of Saccharomycetes. The remaining isolates were identified among three classes of Pezizomycotina: Eurotiomycetes (4 isolates), Dothideomycetes (30 isolates) andSordariomycetes (46 isolates). All Pezizomycotina isolates were placed among clades of terrestrialfungi known to be endophytes in terrestrial ecosystems. None of the isolates were classified among marine lineages. Phylogenetic community structure analyses revealed differences among the four co-occurring species of seagrasses. C. serrulata displayed the lowest phylogenetic diversity as compared to the other three seagrasses. Endophytes of E. acoroides were more clustered in Sordariomycetes than those of T. hemprichii and H. ovalis, which were equally dispersed among Sordariomycetes and Dothideomycetes. Simplicillium, Trichothecium, Stephanonectria, Letendraea, Cochliobolus, Microxylium, Pseudallescheria and Phanerochaete were reported for the first time as endophytes of seagrass hosts. This study indicates that seagrasses can provide a wide variety of fungal endophytes. The most common endophytic fungi found in all four seagrass hosts were Fusarium, Nigrospora and Penicillium. Phylogenetic analyses showed clearly that endophytic fungi from seagrasses are from terrestrial origin.
Keywords: Endophytic fungi, Diversity, Seagrasses and Phylogenetic community structure