Effects of fungal endophyte presence in cool-season grasses native to the Northern Great Plains

Background/Question/Methods

Many cool-season grasses contain fungal endophytes in their aboveground tissues. These endophytes often produce alkaloid compounds which can be toxic to herbivores. Numerous studies have considered the effects of these fungal endophytes in agricultural grasses.  Fungal endophytes in these grasses are known to deter herbivory and their presence might affect small mammal and insect herbivory on the host. However, little research has been done to test the effects of fungal endophytes in native grasses. The purpose of this experiment was to determine if fungal endophyte presence affects vegetation composition in restored grasslands and if herbivores differentially consume native grasses with (E+) and without (E-) fungal endophytes. The experiment was established in northeastern North Dakota in summer 2011 in a randomized complete block design (n= 6). E+ and E- individuals of Elymus canadensis (EC), Elymus virginicus (EV), or Elymus trachycaulus (ET) were planted with Monarda fistulosa and Schizachyrium scoparium in a 5.67L greenhouse pot buried in the ground. Exclosures were built around six of the twelve pots to test effects of fungal endophyte presence on herbivory.

Results/Conclusions

Growth of Elymus trachycaulus, but not Elymus Canadensis or Elymus virginicus was affected by endophyte presence. Overall, E+ ET plants were taller but contained the same amount of biomass as E- ET plants.  Endophyte presence also affected the response to herbivory exposure for ET. E+ ET individuals in enclosed pots had a lower biomass and number of tillers than enclosed E- ET individuals. E- ET individuals in enclosed pots had a higher biomass and tiller count than E- ET individuals that were exposed to herbivory. Vegetation composition was the same between areas exposed to herbivory and areas where herbivory was excluded. Our findings suggest that presence of fungal endophytes within native cool-season grasses may affect herbivore-plant interactions and vegetation composition in restored prairies, however larger scale studies need to be performed to determine if endophyte presence would affect communities planted at common restoration scales.