Plants live in tight association with microbes, especially belowground where fungi and bacteria live on and inside the roots of plants. The relationship can be beneficial or harmful to the plant. Some microbes cause plant diseases by decomposing roots. Others trade nutrients with the roots in return for sugars produced aboveground by leaves.
We investigate two main aspects of the relationship between plants and microbes in the soil. First, as it pertains to weeds, we want to know if soil microbes can help or hinder plant invasions. Three highly invasive weeds of contrasting life history strategies; cheatgrass, knapweed and leafy spurge, co-occur with remnants of native plant vegetation. This creates a unique opportunity to observe, characterize, and manipulate interactions between plants and belowground microbial communities. We outline a number of short, intermediate and long-term research projects that will significantly enhance our knowledge regarding plant microbe interactions and soil processes, with the overall goal to better understand, predict and counteract plant invasions, and to restore and manage invaded ecosystems.
Second, we seek to understand how the relationship between plants and soil influences the function of ecosystem processes. Soil microbes are responsible for organic matter decomposition and nutrient cycling between the atmosphere and the land. On this project we collaborate with the Earth Microbiome Project (EMP). The goal is to map and understand the diversity of microorganisms in habitats around the world. We mapped microbial diversity and function across gradients of weed invasions.
The image above shows a western white pine root colonized by ectomycorrhizal fungi, shown at 8x magnification.
Fungi are heterotrophic organisms and are unable to produce their own food. Instead, they exude enzymes to break down organic material and absorb essential elements, like nitrogen and phosphorus, from their environment.
Ectomycorrhizal fungi (EMF) form mutualistic relationships with plant root tips (Image 1a, arrow). They grow a fungal sheath around the root, and from the sheath, hyphae extend into the soil and increase the plant’s access to water and nutrients. In exchange, the plant provides EMF with the carbohydrates they need to survive. Uncolonized root tips (Image 1b, arrow) lack a fungal sheath and the benefits that EMF provide.
EMF may also have the ability to reduce plant disease caused by insect and fungal pathogens (Bennett et al. 2017, Mateos et al. 2017). In collaboration with the Dorena Genetic Resource Center (DGRC), we hope to determine if EMF influence disease in western white pines exposed to the blister rust pathogen, Cronartium ribicola.
In September 2019, a small subset of western white pine seedlings from the DGRC experiment were harvested to evaluate the effectiveness of our EMF inoculations earlier this year (above). The seedlings were sent to Dr. Peter Kennedy’s laboratory at the University of Minnesota, where they performed the initial processing and assessment of root colonization.
Each root system was cut into multiple pieces and rinsed with water to remove the soil. A portion of the roots were randomly selected for EMF quantification (Image 4, photos by Peter Kennedy). We will ‘score’ the roots by counting the number of colonized root tips. This will allow us to estimate the percent colonization of the root system for each seedling. We will relate this data to disease severity next spring.
Bennett JA, Maherali H, Reinhart KO, Lekberg Y, Hart MM, Klironomos J. Plant-soil feedbacks and mycorrhizal type influence temperate forest population dynamics. Science. 2017 Jan 13;355(6321):181-4.
Mateos, E., Olaizola, J., Pajares, J.A., Pando, V., & Diez, J. J. (2017). Influence of Suillus luteus on Fusarium damping-off in pine seedlings. African Journal of Biotechnology, 16(6), 268-273.
Emily graduated from Montana State University in 2016, earning a B.S. in Biological Sciences with a concentration in Conservation Ecology & Biology and minor in Statistics. While in school, she spent time at MPG Ranch capturing and monitoring painted turtles.
After finishing her degree, Emily worked as a microbiology intern at MPG where she prepared samples for DNA sequencing and cultured fungi from plant tissue. Upon completing her internship, Emily transitioned into her current role as a laboratory technician where she assists with projects relating to plant-fungal interactions, natural history, and light microscopy.
Outside of work, Emily enjoys reading, fishing, and riding her horses across Montana’s beautiful landscape.