Understanding the Microbiome of Puget Prairies: Community composition of bacteria in a hemiparasitic plant system

Abstract

Recent advances in the field of metagenomics have allowed for a boom of research in the field of microbial community ecology. Using DNA extraction techniques, Illumina sequencing, and advanced statistical software, scientists are now able to examine the community composition of microbiomes existing throughout the world. My research examines the microbial communities of Puget prairie plants, which have remained largely unexplored until now. I performed a field study to identify the bacterial communities that comprise the stem microbiomes of 16 native prairie plant species. I discovered that the bacterial communities within Puget prairie plants often differ significantly between plant species, but plant species belonging to the same family often have similar bacterial communities. Additionally, I discovered that bacterial communities differed between samples taken from different sampling locations. I also found that bacterial communities are only affected by disturbances applied several years prior to sampling, and in disturbance regimes applied continuously to research plots, for Cerastium arvense. I explored the theory that the bacterial community within Puget prairie plants could be influenced by parasitic root connections established by Castilleja levisecta, a hemiparasitic plant that attaches root connections to other prairie plants. Testing all samples that could be assigned to trios regardless of species sample size, I found that plant parasitism significantly affects the bacterial communities of Puget prairie plants overall. Testing individual species with large sample sizes, I found an effect of plant parasitism on the microbiomes of parasitic plant C. levisecta for Eriophyllum lanatum and Lomatium utriculatum, and further study of this system with larger sample sizes could reveal an effect of parasitism for Balsamorhiza deltoidea and Festuca roemeri. This research provides valuable information about the types of bacteria that exist within the stem tissues of native Puget prairie plants, and insights into the role that parasitic plants may play in the colonization of bacteria across the Puget prairie ecosystem.