How do stress-adapted microbial communities enhance the tolerance of trees to cold, heat and drought?

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

Tree species can occur across wide ranges that vary greatly in temperature and precipitation. How can a single tree species tolerate such a wide range of conditions? It is increasingly recognized that microbial associates can affect how plants tolerate stressful conditions, which may contribute to their broad geographic ranges. However, very little is known about the mechanisms by which microbes change how trees grow and function under stress. This project seeks to increase the understanding of why trees grow better in certain locations than others, and whether microbial associations from different locations alter plant responses to the environment. Experiments will test whether microbes sourced from colder, hotter, and/or drier locations can promote tree seedling growth and survival under those conditions. Additional measurements will determine the source of this enhanced tolerance through shifts in plant growth, physiological function, and by turning on or off key plant genes during development. This project will directly apply this knowledge to reforestation efforts by working with tree nurseries to promote microbial associations and test the impact on tree seedling survival in restoration plantings. Additionally, this project will continue to support a volunteer led tree root sampling program to map the distribution of tree-fungal associations across the eastern United States. Prior results indicate that tree seedlings inoculated with microbial communities sourced from dry, hot, or cold locations improved seedling survival under those respective stresses. However, we have little understanding of the physiological, morphological, or transcriptional mechanisms underlying these effects. This project seeks to integrate an understanding of broad biogeographic patterns in species interactions with a detailed understanding of plant physiological responses and underlying gene regulatory mechanisms. Microbial mediation of plant abiotic stress tolerance has been documented in a wide variety of systems, but often with little or no understanding of how the microbial interaction changes plant phenotypes or gene expression to result in enhanced stress tolerance. This project will experimentally manipulate soil microbial inocula and environmental conditions, then measure morphological, physiological, and gene regulatory responses in tree seedlings. Additionally, this project will test whether microbial stress mediation occurs in real-world situations by working with tree nurseries to promote fungal associations, then testing the impact on tree seedling growth, survival, and physiological function in outplanting conditions. Finally, this project will continue a volunteer-led project to map the geographic distribution of root-associated fungi across eastern temperate forests. By interrogating plant phenotypic and transcriptomic responses to geographically varying microbial communities in an ecologically informed framework, this project will ensure that this understanding directly connects to our ability to understand and predict natural patterns. 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.