title: Imaging Nutrient Distribution in the Rhizosphere Using FTIR Imaging.
abstract: Symbiotic associations in the rhizosphere between plants and microorganisms lead to efficient changes in the distribution of nutrients that promote growth and development for each organism involved. Understanding these nutrient fluxes provides insight into the molecular dynamics involved in nutrient transport from one organism to the other. To study such a nutrient flow, a new application of Fourier transform infrared imaging (FTIRI) was developed that entailed growing Populus tremulodes seedlings on a thin, nutrient-enriched Phytagel matrix that allows pixel to pixel measurement of the distribution of nutrients, in particular, nitrate, in the rhizosphere. The FTIR spectra collected from ammonium nitrate in the matrix indicated the greatest changes in the spectra at 1340 cm-1due to the asymmetric stretching vibrations of nitrate. For quantification of the nitrate concentration in the rhizosphere of experimental plants, a calibration curve was generated that gave the nitrate concentration at each pixel in the chemical image. These images of the poplar rhizosphere showed evidence for symbiotic sharing of nutrients between the plant and the fungi, Laccaria bicolor, where the nitrate concentration was five times higher near mycorrhizal roots than further out into the rhizosphere. This suggested that nitrates are acquired and transported from the media toward the plant root by the fungi. Similarly, the sucrose used in the growth media as a carbon source was depleted around the fungi, suggesting its uptake and consumption by the system. This study is the first of its kind to visualize and quantify the nutrient availability associated with mycorrhizal interactions, indicating that FTIRI has the ability to monitor nutrient changes with other microorganisms in the rhizosphere as a key step for understanding nutrient flow processes in more diverse biological systems.
authors.affiliation: Department of Chemistry, Stony Brook University , Stony Brook, New York 11794, United States.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Victor
authors.affiliation: National Synchrotron Light Source II, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Natalie
authors.initials: N
authors.lastname: Delpratt
authors.affiliation: Department of Biological Science, University of Alabama in Huntsville , Huntsville, Alabama 35899, United States.
authors.forename: Sarah Beth
authors.initials: SB
authors.lastname: Cseke
authors.affiliation: Department of Chemistry, Stony Brook University , Stony Brook, New York 11794, United States.|National Synchrotron Light Source II, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Lisa M
authors.identifier: 0000-0002-2912-7991
authors.initials: LM
authors.lastname: Miller
authors.affiliation: Department of Biological Science, University of Alabama in Huntsville , Huntsville, Alabama 35899, United States.
authors.forename: Leland James
authors.initials: LJ
authors.lastname: Cseke
mesh_terms: D055399:Laccaria / Q000378:metabolism; D038821:Mycorrhizae / Q000378:metabolism*; D009566:Nitrates / Q000032:analysis / Q000378:metabolism; D000078622:Nutrients / Q000032:analysis / Q000378:metabolism*; D032107:Populus / Q000378:metabolism / Q000382:microbiology; D058441:Rhizosphere; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013395:Sucrose / Q000032:analysis / Q000378:metabolism
chemical_list: D009566:Nitrates; D000078622:Nutrients; D013395:Sucrose