Interestingly, our work has shown that the plant does not pay a growth penalty whether it is a high or low producer of SWA, and production is under tight fungal or plant genetic control because SWA production is locoweed taxa specific and possibly also Undifilum taxa specific. Furthermore, we have found that there is no discernable difference in antioxidant response between plants with the fungal endophyte (E+) and those in which the endophyte was mechanically removed  (E-), suggesting the endophyte is not providing a stress response fitness benefit as seen occurring in the grass-endophyte symbiosis. The fungal endophyte-locoweed interaction is asymptomatic for locoweed based on our biomass data. However, our preliminary data indicates that antimicrobial compounds are decreased in E+ plants over that of E- plants and also in mechanically wounded E+ vs. unwounded E+, suggesting the fungus may be regulating the plant’s defense mechanisms to allow for infection or vertical transmission. How this may affect the over-all fitness of the plant is not yet known and determining the extent of the regulation is a major emphasis for my lab. Our current efforts are focusing on developing a better understanding of the unique and agriculturally important fungal endophyte-locoweed plant complex, including the investment that locoweed plants make towards SWA production by the fungal endophyte and the cost/benefits to locoweeds by hosting U. oxytropis.

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