Last month Sarah Evans, Maren Friesen, and Tayler Chicoine traveled to Washington D.C. to attend and present at the DOE 2018 Genomic Science Annual PI Meeting.
Check out the abstracts from their presentations below:
Evans, S., J. Cole, M. Friesen, S. Gougherty, L. Tiemann. Plant and Biogeochemical Controls on the Switchgrass Microbiome: Perspectives from a fine-scale time series. Washington D.C. Feb 25-28, 2018.
Nitrogen (N) is the most commonly limiting nutrient for plants, especially in marginal lands. These lands are unsuitable for food crops because of low productivity and vulnerability to environmental stress. The introduction of perennial bioenergy cropping systems (PBCS) in marginal lands can improve whole system N use efficiency and N retention, while also
contributing to energy sustainability without competition with food. However, little is known overall about N-cycling and associated microbial function in marginal land biofuel cropping systems. As part of a project studying Microbial-Mediated Perennial Rhizosphere Nitrogen
Transformations (MMPRNT), we have begun to characterize N-cycling microbial communities and associated plant and soil biogeochemical properties in six marginal land sites in Michigan and Wisconsin. Sites are part of the DOE Great Lakes Bioenergy Research Center (GLBRC), and including different cropping systems (switchgrass, prairie, control) and fertilized and unfertilized plots. A unique aspect of this study is the temporal resolution at which we measured properties; at our focal site, we looked at these properties in 2-week time intervals, at another site
on a monthly basis, and at all sites 1x/season.
We found that overall, site was the strongest factor explaining microbial and biogeochemical dynamics, but that microbial communities and soil nitrogen pools varied widely on relatively short temporal scales. For instance, microbial community composition varied as much over time
as it did in fertilized and unfertilized plots in a single site. Fertilizer affected soil and microbial characteristics after being applied in spring, but we saw surprisingly few long-term effects of this treatment on soil or plant traits. An improved method for measuring free-living N fixation revealed that N-fixation is occurring in switchgrass, and may be especially prominent near
senescence. These field data will complement other lab and greenhouse mesocosms and field manipulations in our project, which will be used to parse out mechanisms for many of these patterns.
Chicoine, T., S. Roley, G. Robertson, S. Evans. Soil- and Root-associated Microbiomes Across Twelve Switchgrass Cultivars. Washington D.C. Feb 25-28, 2018.
Switchgrass (Panicum virgatum), a C4 perennial grass, is known to associate with beneficial microbial communities that may enhance its potential as a low-input bioenergy crop. Genetically distinct cultivars adapted to southern and northern regions of the United States differ in their
tolerance to marginal, low-input production systems, but the extent to which microbial communities influence this variation is unknown. We hypothesized that different microbial communities, and specifically more abundant free-living Nitrogen (N)-fixers bolster the ability of
some cultivars to tolerate N-limited soils. Further, we hypothesized that cultivars’ specific root length (total root length/total dry weight), previously shown to correlate with switchgrass root derived carbon, may contribute to differences in the cultivars’ microbial communities. Here,
we measured N-fixing potential, root traits, and fungal and bacterial communities (16S, ITS, nifH abundance) in soils and roots of 12 switchgrass cultivars (including upland and lowland ecotypes) at the Great Lakes Bioenergy Research Center at Kellogg Biological Station in southwest Michigan. Preliminary findings suggest that bacterial and fungal community compositions do not differ among the cultivars or by ecotype. We will also present results on the relationships between N-fixation potential, N-fixer abundance, and root morphology among the
cultivars. This study will inform our understanding of how plant-microbial interactions can support sustainable switchgrass bioenergy production.
