Plant-microbe interactions

Fig 1.—Relative yield of the duckweed Lemna minor is in part a product of the local microbial community. The culture on the left is an axenic, whereas the culture on the right contains a growth-promoting bacterium.

Fig 1.—Relative yield of the duckweed Lemna minor is in part a product of the local microbial community. The culture on the left is an axenic, whereas the culture on the right contains a growth-promoting bacterium.

I have developed duckweeds (Lemna spp., Wolffia spp., Spirodela spp.) into a tractable model system in which to study plant-microbe interactions. Currently, I am using this system to investigate how plants and microbes compete for nitrogen in aquatic habitats, and how microbes may contribute to competitive interactions among duckweed species.

A primary goal of my disseration research was to demonstrate links between changing microbial communities and the functioning of their ecosystems (or hosts). To accomplish this, I studied how microbial communities develop and change over time within the digestive leaves of the carnivorous pitcher plant Darlingtonia californica. This unique plant relies on a microbial food web to break down captured insect prey in a manner somewhat analagous to our own microbiota. My research entailed enumerating all compartments of pitchers' communities (viruses, bacteria, protists, & arthropods) and linking their dynamics to rates of carbon and nitrogen mineralization using stable isotope tracers and respirometry. My results indicated strong associations between community turnover, biomass degradation, and host nutrient uptake.

Fig. 2 - A particularly handsome patch of Darlingtonia californica growing in the Sierras.

Fig. 2 - A particularly handsome patch of Darlingtonia californica growing in the Sierras.

Fig. 3 — Developmental trends in the microbial digestive communities found in leaves of the pitcher plant Darlingtonia californica. Points closer together denote more similar bacterial communities. 

Fig. 3 — Developmental trends in the microbial digestive communities found in leaves of the pitcher plant Darlingtonia californica. Points closer together denote more similar bacterial communities.