POSTDOCTORAL NSF PRFB RESEARCH
Stressors such as high temperature, drought, and salt can lead to reduced crop yields and billions of dollars of crop loss each year. To feed a growing global population, innovative new agricultural methods must be developed to improve plant stress tolerance and crop yield. One emerging method to meet these goals and increase crop performance in a warming climate is through design and application of climate-selected microbial communities; however, we currently have little basic understanding of how existing microbial communities (microbiomes) influence plant performance at elevated temperature.
My postdoctoral research investigates how microbial communities change inside or on the surface of a plant at elevated temperature, and the impact those changes have on plant health. Using a combination of molecular, multi-omic, and mathematic modeling approaches, my work is addressing knowledge gaps in “temperature-microbiome-plant” triangular interactions and revealing underlying principles of emergent plant and microbiome function(s) in warming conditions.
Previous research suggests that microbiomes can perform specific functions in defined abiotic conditions. Separate findings show that plant physiology, development, and phenotype can be dramatically influenced by abiotic factors, such as elevated temperature. By simultaneously examining changes in microbial composition and plant performance at elevated temperature this project has the potential to reveal new principles of host-microbiome-environment interactions that could apply even beyond plant systems.
This research will be used to improve current predictive models for microbiome changes that can be directly tested in crop species. Through this project, I am furthering my graduate training by developing a multidisciplinary research skill set and gaining additional skills in scientific mentoring and lab management.
Key questions for this project include:
1) Does elevated temperature alter microbiome composition differently with and without a plant present and why?
2) Do the plant microbiomes alter plant phenotypes differently at different temperature and why?
3) Can we apply the knowledge of plant-microbiome-temperature interactions learned from A. thaliana to crop systems?
As a result, bacteria have evolved many mechanisms to deal with stress, including systems designed to pump toxic molecules out of the cell. One of these mechanisms is the formation, packaging, and release of outer membrane vesicles. All bacteria produce vesicles. In Gram-negative bacteria, which have an inner membrane and an outer membrane separated by a thin layer of peptidoglycan, vesicles bud off of the outer membrane. To help deal with stress, bacteria package these vesicles with misfolded proteins and other compounds that are toxic to the bacterial cell.
However, vesicles are also used for more than defense against stress. Mammalian pathogens package vesicles with virulence factors that harm the host and help the bacteria survive. In fact, vesicles are a very successful strategy for packaging hydrophobic toxins and protecting soluble proteins from degradation in the harsh host environment.
Bacteria encounter a wide array of stress in their environment, particularly in the context of host-pathogen interactions. For example, when a human has a bacterial infection their immune system works to eliminate the pathogen through heat stress (fever) and sending immune cells to the site of infection (inflammation). These immune cells can sometimes capture the pathogen leading to even more stress for the bacteria such as oxidative and pH stress.
While research has uncovered many roles for vesicles in the context of mammalian host-pathogen interactions, very little is known about the role of bacterial vesicles in the environment. One way to study interaction with the environment is in the context of plant host-pathogen interactions.
Key findings from my work so far:
1) bacterial vesicles from plant pathogens and plant beneficial bacteria activate plant immune responses
2) vesicle-mediated plant immune pathways protect against future bacterial and oomycete challenge
3) protein content of vesicles from plant bacteria revealed known plant-active molecules and points to different roles for different types of bacterial vesicles