Here are a few highlights:
- All plants in natural ecosystems are symbiotic with fungal endophytes.
- Fungal endophytes may increase plant fitness by boosting stress tolerance, increasing biomass and decreasing water consumption, or decrease fitness by altering resource allocation.
- C-endophytes are found in grass species. C-endophytes produce toxins that deter grazing by many insect and even mammal species. For example, sleepy grass (Achnatherum robustum) contains an endophyte that causes horses who eat small quantities of the grass to sleep up to 3 days. When the horses recover they will avoid the plants. This type of grass-endophyte mutualism is seen worldwide. There is evidence that some C-endophytes may improve water and nutrient uptake as well as protect grasses from other fungal infections but this depends on species specific interactions.
- NC-endophytes are highly diverse and found in most plants. Despite a large number of studies(1000+ since 1970) few have examined the functional roll of NC-endophytes. There are three functional groups of NC-endophytes. Class 2 - Colonize roots, stems and leaves; vertically or horizontally transmitted; broad host range. They increase plant and shoot biomass as well as confer tolerance to abiotic and biotic stresses such as disease, drought, desiccation, heat and salinity. Class 3 – Colonize above ground tissues; horizontally transmitted; broad host range. Include the hyper diverse endophytic fungi associated with leaves of tropical trees and above ground tissues of many plants worldwide. Ecology and function are not well understood. Science may need to look at wider microbial community ecology. Class 4 - Colonize roots; horizontally transmitted; broad host range
Clearly, before functional diversity is assigned to OTU groups for ecological comparisons, a great deal of work needs to be done to determine the roles of the highly diverse fungal endophyte groups.