Background/Question/Methods Mycorrhizae associate with approximately 80% of plants and can alter the realized phenotype of host plants through changes in plant nutrition, performance, and chemistry. While maintaining mutualists imposes a carbon cost on the plant host, plant growth and performance under stressful conditions may still be buoyed by mycorrhizae sending nutritional support from belowground. Although the benefits of mycorrhizae towards plant performance under drought conditions are well-studied, it has long been assumed that mycorrhizae have limited benefits in high water conditions due to hypoxic soils. Climate change may exacerbate not only desertification but also soil inundation at local and regional levels. Exploring how mycorrhizae alter the performance, nutrition, and niche breadth of their host plants under stressful conditions will allow us to better predict how mycorrhizae might alter plant resilience under climate change regimes. Here we directly test whether or not mycorrhizae mediate plant performance of a common forb, Solidago altissima, across a range of eight watering conditions in a full factorial greenhouse experiment. Results/Conclusions Preliminary data analysis suggests that mycorrhizae not only increase plant performance, but also may provide a buffer against the cost of high stress environments on plant performance. Watering amount significantly influenced plant biomass (P = 0.0345), as did mycorrhizal status (P < 0.0001), but most interestingly, we detected a significant interaction between mycorrhizal status and watering amount on plant performance. S. altissima individuals grown without mycorrhizae suffered lower performance and biomass at high watering conditions while S. altissima grown with mycorrhizae maintained their biomass (P < 0.0001). Additionally, we are conducting further analyses on soil moisture, plant nutrients and plant chemistry. Not only does these preliminary results suggest that mycorrhizae may play an unexpected role in ameliorating plant stress in high water conditions, but this work also indicates that mycorrhizae may extend or expand the realized niches of their plant hosts. Plants with broader environmental niches may be more resilient to shifts in precipitation and soil nutrition regimes. Thus, mycorrhizae-mediated plant resilience has the potential to shape agricultural and restoration decisions as well as environmental forecasting.
