COLLABORATIVE RESEARCH: Parsing the effects of host specificity and geography on plant-fungal symbioses under climate change

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Climate models project higher temperatures, more variability in precipitation, and more extreme weather events in the future. Under such changing environments, foundation plant species, which promote stable conditions for other species and support fundamental ecosystem processes, may benefit from microbial partners that enhance plant survival during climate extremes. However, whether microbial partners can help buffer ecosystems against climate change remains unknown. This research investigates a widespread, but poorly known, group of fungi that commonly grow in the roots of dominant forage grasses. The project determines how the benefits of these fungi vary along gradients of drought and heat stress, differ among grass species, and shift across geographic regions. This work has high promise for identifying fungi that help plants survive and grow in stressful climates. Together, this team will integrate research activities into a new high school teacher training program that focuses on underserved communities and a set of laboratory modules for middle school workshops. Results will shed new light on the functions of microbial partners in maintaining grassland and rangeland productivity, improving the ability to conserve, manage, and restore these important areas in future climates.Deeper insight into the biology of root endophytes has the potential to transform understanding of how plants respond to drought and heat in the same way that studies on mycorrhizal fungi overturned paradigms about how plants acquire nutrients. This project tests whether root-associated fungi benefit dominant grassland plant species, which may moderate the loss of net primary production during droughts and heat waves. The work addresses the following questions: (1) What is the relative importance of host species identity versus geographic and climatic gradients in explaining variation in symbiont abundance and composition? (2) How strongly do host species identity and geographic origin influence the magnitude of symbiont benefits across gradients of heat and drought stress? (3) Can symbiont-mediated amelioration of stress be generalized from laboratory settings to predict outcomes in the field? Activities include field surveys along latitudinal gradients, next-generation high-throughput sequencing of root fungi, development of a large fungal culture collection, multi-factor greenhouse trials that manipulate drought and heat, and field tests that leverage existing, large, cross-site rainfall experiments. Novel aspects of this project include characterizing root-associated fungal composition along latitudinal gradients, testing the hypothesis that symbioses become more beneficial to plants under increased abiotic stress, and determining how endophytic root fungi affect plant hosts under field conditions.