CAREER: How plant genotype and environmental factors jointly influence the structure of microbial communities and plant health

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117- 2).

Understanding how host organisms and their resident microbial communities interact is a central challenge in biology, with broad implications ranging from agriculture to human health. A primary question is what factors and mechanisms shape the composition of microbial communities. A related issue is whether and how the structure of microbial communities affects the host.

This project addresses these two questions by focusing on how distinct environmental factors, in combination with host genetic variation, shape the composition and functional influence of microbial communities. The work will take advantage of an established, highly accessible plant-fungal symbiosis in Populus, in which leaf endophytes are known to confer disease protection.

A complementary educational program will enrich and broaden the research through student-led work investigating seasonal variation in the drivers of endophyte community structure in common gardens and in greenhouse experiments. Overall, this CAREER project will deepen our understanding of how environment and genotype affect endophyte communities and disease protection in plants, while promoting diversity in a STEM field and contributing to conservation and crop production in the face of climate change.

Interactions between plants and their associated microbial communities are known to be sensitive to the environment, but the underlying drivers of this variation are poorly understood. This CAREER project tests mechanistic hypotheses for how plant genotypes interact with distinct, abiotic and biotic components of the environment to give rise to variation in associated microbial communities.

This work will be conducted in the cottonwood model system (Populus trichocarpa), in which host genetics, leaf fungi, and distinct environmental factors can be precisely controlled and quantified. The first objective tests how distinct environmental factors and plant genotype jointly influence the composition of fungal leaf endophyte communities. The second objective is to understand how endophyte community structure affects plants, specifically testing the hypothesis that increasing phylogenetic diversity in an endophyte community provides the host plant with a higher degree of disease protection.

The third objective connects the prior two objectives by testing how a particular plant trait (the level of cuticular wax) influences endophyte community structure, thereby indirectly affecting disease susceptibility. By elucidating the environmental sensitivity of host control over beneficial fungi, the results of this CAREER project will inform global efforts to conserve plant biodiversity and to sustainably grow crops for a growing human population.

The educational components of the project will provide research opportunities to a diverse group of high school, undergraduate and graduate students, and a postdoctoral scholar.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.