Using a global weed to disentangle environment and host effects on plant-microbe interactions across nested spatial scales
Understanding the factors that control the distributions and abundances of species is the central goal of community ecology. In the last two decades, two previously underappreciated facets of controls on species distributions have risen to the fore: 1) the degree to which regional, dispersal-driven processes affect distributions at local scales; and 2) the prevalence and importance of symbioses and other close associations. When added to the classic focus on local environment and species interactions, these emerging facets begin to paint a more complete picture of controls on species distributions. Due to their discrete nature and fixed spatial arrangement, plant-associated microbial communities offer an ideal system to study the influence of multiple factors on rhizosphere assembly: local environment, host genotype, microbial dispersal, and the interactions among those factors. Furthermore, plant-associated microbial communities strongly impact plant performance, and evidence is increasing that microbiome characteristics may facilitate success among invasive plants.
Using a single host plant across its distribution will allow us to evaluate how assembly of its associated microbial community changes across environmental conditions while controlling for host effects. Johnsongrass is globally widespread, locally abundant, and has been the subject of considerable prior research by Co-PIs Barney and Haak. We propose to use the widely distributed invasive weed, Johnsongrass (Sorghum halepense), for two main purposes: 1) disentangle the factors that shape microbial community assembly across scales ranging from a single plant to an entire hemisphere; and 2) identify plant-microbiome associations related to plant performance to be used as hypotheses in future proposals.
While our larger project has fairly expansive goals, this seed proposal will result in key preliminary data, and also serve multiple missions of the GCC:
- How do Johnsongrass-associated rhizosphere microbiomes vary by environmental conditions and distance between plant patches
- Integrate results from this work into an IGC course on microbial data analysis
Integrating seed grant results into IGC graduate class
Co-PIs Badgley and Haak will again offer GRAD 6984: Microbial Community Analysis to IGC and other students in Fall 2021. The course covers practical, hands-on bioinformatic and statistical analysis of microbiome data sets, and as part of the instruction students work with a standard class dataset from a real project before later applying those skills to their own data. Our seed grant results will be used as standard class data in Fall 2021. Once analyzed, Co-PIs Brown and Barney will be invited to participate for a 2-3 week module discussing how the results contribute to our ecological understanding of both microbiomes as well as invasive species. Our goal will be to provide IGC students with an interdisciplinary perspective that spans two Creative Collision areas within the GCC, and build momentum for developing cross-collision interactions and collaborations in the future.
Reference citations for project proposal description available upon request.