Bacterial and fungal endophyte communities differ in trees of natural versus wastewater-treatment wetlands

Abstract

Little is known about the microbiota that form symbioses with wetland plants. We describe how endophytes from leaves and roots of baldcypress trees changed along a nutrient gradient and differed in wastewater treated versus untreated wetlands. Cultured bacterial and fungal endophytes were most abundant and diverse in baldcypress roots (compared to leaves) for both treated and untreated wetlands. Bacterial endophyte abundance increased with increasing distance from the wastewater outfall pipe, while fungal endophytes decreased with increasing distance from the wastewater outfall pipe—showing a greater abundance of fungi where nutrients were greatest. Bacterial endophyte abundance and species richness were greater in the wastewater-treatment compared to untreated wetlands, but diversity metrics suggested this was due to incomplete sampling at some sites. Community composition of endophytes in the treated wetland differed from some but not all of the communities observed in untreated wetlands. Since baldcypress is a key restoration species for declining swamps in the southeastern US, our descriptive work provides a foundation for future studies to understand the functional roles of plant-microbial interactions and community patterns.