COS 43-8
Does a fungal endophyte have a different impact on the competitive interactions of its host with native and exotic plant species?
Endophytic fungi from the genus Neotyphodium infect a variety of grasses. The endophytes provide multiple benefits to their hosts but little is known about their role regarding the host’s interactions with other plant species in communities. To fill in this gap we addressed the following questions: 1) Do the competitive responses between the exotic grass tall fescue (Schedonorus arundinaceus) and exotic and native co-existing plant species vary depending on the presence of the tall fescue’s N. coenophialum endophyte?; 2) How does the endophyte affect the mycorrhizal network established between its host and other plants?; and 3) How does the endophyte affect the tolerance of its host and of neighbouring plants against enemies? Using double compartment pots containing soil collected from an old-field plant community we grew tall fescue (with or without its endophyte) either alone or together with six co-existing plant species pairs. Each pair consisted of a closely related North American and an European (from tall fescues’ geographic range) species, with two pairs per family; Poaceae, Asteraceae and Fabaceae. We determined competitive response for plant biomass. We also measured mycorrhizal colonization and the incidence of enemy attack (lesions) to the roots of plants growing either alone or together.
Results/Conclusions
The endophyte alleviated the competitive response of its host against other plants. However, this effect was similar regardless of whether tall fescue’s competitors were native or exotic plants. In contrast, the endophyte did not have a significant effect on the competitive response of the various competitor plant species against tall fescue. Belowground, the endophyte reduced the mycorrhizal colonization of its host when growing alone. However, this effect was alleviated when tall fescue interacted with another plant. Moreover, the endophyte reduced enemy attack against its host’s roots, especially when growing together with other plant. It also reduced the mycorrhizal colonization and lesions of the plants growing with tall fescue and the effect on mycorrhizal colonization was stronger for native than for exotic plants. We conclude that the endophyte of tall fescue provides a competitive advantage to its host. In addition, our data suggest that this effect is due, at least partially, to reductions in root enemy attack, while common mycorrhizal networks between interacting plants alleviate the negative effects of the endophyte on these mutualists.