Biodiversity of fungal endophyte communities inhabiting switchgrass (Panicum virgatum L.) growing in the native tallgrass prairie of northern Oklahoma

This study was conducted to explore fungal endophyte communities inhabiting native switchgrass plants from the tallgrass prairie of northern Oklahoma. The primary focus was to isolate these endophytes in pure culture from surface-sterilized plant tissues and provide taxonomic identifications based on comparative analysis of ITS rDNA gene sequences. From these data, we evaluated the biodiversity of these potentially beneficial endosymbionts from this rapidly disappearing habitat of the Great Plains. While important from a strictly conservationist standpoint, this survey further allowed us to identify candidate endophytes for introduction into commercial switchgrass cultivars for biomass enhancement. A total of 210 whole plant samples were collected at early vegetative, full reproductive and senescence stages. Fungal endophytes were isolated, identified to species level when possible, and grouped into communities based on plant part, collection month and part of the prairie from which the plants were collected. Species diversity for each community was estimated by Shannon diversity index, and differences in diversity indices were compared using a t-test. The presence of fungal species representing at least 18 taxonomic orders suggests a high level of diversity in switchgrass endophyte communities. The fungal communities from shoot tissue had significantly higher species diversity than communities from the root tissue. The abundance of taxa assigned to the order Hypocreales (to which mutualistic, clavicipitaceous endophytes of cool-season grasses belong) found in shoot (64%) and root tissues (39%) throughout the growing season suggests great potential for utilizing these endophytes for enhancing biomass production and stress resistance of this important bioenergy crop.