Variation in Microbial Communities and Nitrogen Transformation Rates among Switchgrass Varieties

Chicoine, Tayler, Sarah S. Roley, G. Philip Robertson, Lisa Tiemann, Maren Friesen, Sarah Evans

Presented at the All Scientist Meeting and Investigators Field Tour (2017-10-06 to 2017-10-07 )

Switchgrass (Panicum virgatum) is a C4 perennial grass with unique nitrogen (N) conservation strategies that give it potential as a low-input bioenergy crop. A recent study found that a higher-yielding switchgrass variety associated with a larger and more active community of free-living N-fixers (diazotrophs) than a lower-yielding variety. Root morphology, also shown to vary among switchgrass varieties, is known to influence root exudation rates, which directly impact the amount of carbon © available to energetically-demanding N-fixation. We are investigating the relationship between root morphology, microbial community structure, and N-fixation potential across 12 switchgrass varieties (including upland and lowland ecotypes), at the Great Lakes Bioenergy Research Center at Kellogg Biological Station in southwest Michigan. Preliminary results suggest that switchgrass ecotypes differ in root morphology and N-fixation, but that bacterial community compositions do not differ. Discerning what plant characteristics support diazotrophic communities has large implications for the development of low-input agricultural systems.