Intraspecific variation in plant-microbial interactions
This work was just published - check it out here! Plants can have species-specific effects on the structure and function of associated microbial communities, but recent studies also indicate that different genotypes (or cultivars) within the same plant species may associate with distinct microbial communities. It is common that different crop cultivars have different productivity, traits, and tolerance to abiotic stresses, but there has been less focus on intraspecific variation in microbial communities and, further, if particular plant traits drive these differences. A better understanding in the degree of variation and drivers of a crop's microbial communities will help inform more targeted microbial-host breeding efforts. For my first PhD project, I investigated if different cultivars of switchgrass, a C4 grass with potential as a bioenergy crop, associate with distinct bacterial and fungal soil and root communities. I found that the cultivars had distinct soil bacterial and fungal community composition, but that there were fewer intraspecific differences in the in their root microbiomes. The cultivars also had distinct root traits, which contributed to variability in the soil microbiomes. Still, despite evidence for cultivar-specific microbial conditioning, spatial variability in soil conditions had the largest effect on soil microbiome structure; therefore, more research is still needed to understand the degree to which plant-hosts manipulate soil communities relative to per-existing soil heterogeneity. ***This project was conducted on twelve switchgrass cultivars (established in 2009) at the Great Lakes Bioenergy Research Center at the Kellogg Biological Station in southwest Michigan.
Neighboring plants and their microbial interactions
Changes in plant diversity influence microbial community composition and function, but the mechanisms that underlie these patterns are still debated. A common hypothesis is that more diverse plant communities will additively increase belowground resources (root biomass and root exudates) and, therefore, stimulate a more abundant and diverse microbial community. However, large-scale, plot level, studies of these dynamics fail to capture individual plant-plant interactions that could non-additively influence microbial communities. Localized, species-specific plant neighbor interactions and historical planting contexts can have been suggested to alter plant-microbial associations, but the mechanisms for these shifts is unknown. My research investigates how interactions with neighboring plant species alters a focal plant’s microbial community structure and function. Root exudates, or complex soluble mixtures of carbons and secondary metabolites, are central to plants' interactions with one another and their microbial communities. Therefore, I predict that root exudates are likely a primary mechanism driving neighbor-induced changes in microbial communities. In my research, I use a combination of greenhouse and lab-based experiments, untargeted metabolomics, and microbial sequencing to determine the mechanisms by which neighboring plants alter each other's microbial communities. Understanding how plant-specific interactions mediate microbial associations is a key area of research for both predicting relationships between plant and microbial communities and for informing more successful combinations for intercropping.
Farmer views on soil health and microbial products
Soil health is an increasingly common phrase that promises to sequester carbon and increase farm resilience, but little is known about how farmers conceptualize soil health and how their understanding informs management decisions. With many tools in their toolboxes, farmers have to decide when to invest in longer-term soil health solutions (e.g. cover crops) and when to consider newer technologies, such as microbial, biological products. I'm interested in how farmers' understanding of soil health influences their management decisions, such as willingness to add microbial products to their fields.
My research uses survey, interview, and mental modeling methods to investigate how farmers in southwest Michigan consider soil health in their management decisions and, further, what factors underlie their understanding of soil health. Peoples’ mental models inform how they interpret and understand the world and, therefore, communicate with others and make decisions. My research will describe variation in farmers’ mental models of soil health, which will help inform areas for further education and outreach that can improve adoption of soil health practices.