Microscale analysis of nitrogen transfer in plant rhizosphere-microbial networks
EMSL Project ID
48329
Abstract
Anthropogenic inputs of reactive nitrogen (NH4+, NO2-, NO3-) in agriculture, supporting about 40% of the world's population, will increase with population growth and anticipated investments in bioenergy crop cultivation. The environmental costs include nitrate contamination of groundwater, reduced soil fertility, regional nutrient imbalances, increased emissions of atmospherically active gases (NOx and N2O), and extensive eutrophication of coastal regions (1). The fate of reactive nitrogen (Nr) is generally evaluated by systems-level measurements, primarily crop yield and loss of Nr due to nitrate leaching and N2/N2O emissions (2). However, processes routinely measured at the macroscale are controlled at the microscale by soil microbiota, both competing and cooperating with plants for available Nr. Thus, the primary objective of this proposal is to use EMSL technology to map the microbial conduits for nitrogen transformation and transfer to plants. The proposed research builds on a new model system, the intercropping of nitrogen-fixing alfalfa and switchgrass, a model bioenergy crop. This research is motivated by preliminary findings that nitrogen transfer from alfalfa to switchgrass is in part controlled by a microbial network comprised of arbuscular mycorrhizal fungi and ammonia-oxidizing archaea active in the mining and transfer of nitrogen species originating from the nitrogen-fixing Rhizobium symbionts of the alfalfa. Specific objectives include: 1) delineating the kinetics, routes, and forms of N transfer within and between plants via the microbial network using 15N labeling and high resolution mass spectrometry and 2) complementary analyses using stable isotope probing (SIP) for genetic and proteomic characterization of interacting populations.The proposed analyses will contribute to the development of a low cost and environmentally benign bioenergy agriculture (a central BER mission) by using the state-of-the-art mass spectrometry capabilities of EMSL to: 1) delineate the routes and kinetics of nitrogen species transfer between plants of bioenergy relevance using 15N labeling, and 2) localize and identify metabolites and participating enzyme systems active in nitrogen transfer within the root-hyphal system.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2014-10-01
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members