UBC Theses and Dissertations
Examining ecological determinants of community formation and stability in the root microbiota Aleklett, Kristin Anna Eva
The root system of a plant is known to host a wide diversity of microbes that can be beneficial or detrimental to the plant. Microbial ecologists have long struggled to understand the factors influencing the composition of these communities. One overlooked aspect of microbial community assembly in root systems is the potential for individual variation among plants, and the potential effect of early colonisation events such as microbial exposure of the seed inside the parent plant and during dispersal. In this dissertation, I relate ecological theory of community assembly to the formation of the root microbiota. I explore the extent of variation between individuals in wild plant populations, and examine the effects of historical contingency in determining bacterial and fungal community assembly and stability in the root microbiota. The main findings in my work showed that: - Wild plants growing in close proximity, sharing environmental conditions will still host distinct bacterial communities in their root systems based on their species identity. We also documented individual variation in root microbiota within all species examined, even the clonal plant species Pilosella aurantiaca. - Bacterial community composition varies significantly across the body of a plant, with different parts of the plant body hosting distinct communities. - Plants are able to form new microbial associations throughout development, but the timing of microbial exposure affects the composition of the microbial community in mature plants. - Microbial community stability fluctuates within weeks during early plant development, with one week-old plants hosting communities most likely to change in composition.
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Attribution-NonCommercial-NoDerivs 2.5 Canada