In situ characterization of associations and resource exchange between free-living nitrogen-fixers and switchgrass
EMSL Project ID
51286
Abstract
The process by which atmospheric N2 is converted into ammonia by bacteria is energetically expensive. Diazotrophs living in the rhizosphere (root surface and associated soil) of bioenergy crops, such as switchgrass, perform free-living nitrogen-fixation (FLNF) and are very likely important supporters of productivity, particularly in N limited systems such as marginal lands. In order to truly understand the role of FLNF at the ecosystem scale, we need a mechanistic understanding of how the association between diazotrophs and switchgrass results in C and N exchange. We aim to better understand how interactions between N-fixing diazotrophs and switchgrass, a cellulosic bioenergy crop, and their exchanges of C and N in the rhizosphere by establishing where diazotrophs live on switchgrass root surfaces; assessing the potential for and rates of N-fixation on switchgrass root surfaces and if and where plant root C and diazotroph fixed N are being exchanged. The work we propose can only be conducted at EMSL where we can use a unique combination of equipment and expertise to map colonization of roots by diazotrophs (FISH) and spatial patterns in N-fixation (NanoSIMS), visualize where C and N are being exchanged in the rhizosphere (NanoSIMS), explore root exudate chemistry in relation to diazotroph root colonization and FLNF (metabolomics) and assess cellular mechanisms for N export from diazotrophs (proteomics). With this work we hope to discover the optimal rhizosphere conditions for facilitating FLNF so that this information can be used for breeding and cropping system management in order to maximize switchgrass productivity without chemical fertilizer inputs. This work supports DOE’s mission of “enabling more confident redesign of microbes and plants for sustainable biofuel production.” In addition, this proposal would support the research of a DOE Office of Science Graduate Student Research (SCGSR) Program Fellowship recipient.
Project Details
Start Date
2020-04-13
End Date
2021-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members