Diversity of Fungal Endophytes from Zostera marina Eelgrass in False Bay Biological Preserve

Abstract

Endophytes are organisms such as fungi and bacteria that live at least part of their life cycle inside a photosynthetic host. Fungal endophytes have been found in nearly every plant we have looked at, including seagrasses like Zostera marina eelgrass. As part of the host plant’s microbiome, fungi can affect how its host responds to stressors in its environment, but these relationships have not been well studied in the marine environment. The community of endophytic fungi can vary per host species and from site to site. For this study, the aim was to establish the diversity of fungal endophytes in two patches of Zostera marina in False Bay Biological Preserve on San Juan Island, WA, USA. Surface sterilized eelgrass leaves were plated onto Potato Dextrose Agar. Cultured growths were isolated and then analyzed based on macroscopic and microscopic morphology to identify the lowest possible taxonomic rank. Two fungi were successfully cultured: a Cladosporium species and a Mucor species. There were also five macroscopically distinct bacterial colonies cultured. Cladosporium was only found in the subtidal patch and Mucor was only found in the intertidal patch, indicating site-to-site difference in the microbial communities. While both of these genera of fungal endophytes have been studied for their benefits to terrestrial crop plants, it is still unknown what costs or benefits Z. marina in False Bay might incur from hosting these endophytes. Further study is needed to characterize these host-fungi interactions in seagrasses. Keywords