Magnetic susceptibility shift selected imaging (MESSI) and localized1H2O spectroscopy in living plant tissues

Maize root segments permeated with aqueous solutions of the paramagnetic agents GdDTPA2− or DyDTPA-BMA display two well-resolved NMR peaks corresponding to the signals from intracellular and extracellular 1H2O, which arise from well-understood bulk magnetic susceptibility effects. This allows each component to be studied separately. Images obtained at each frequency with MESSI editing, and single- and multiple-voxel (‘spectroscopic imaging’) localized spectra, clearly indicate that the agents permeate into the interstitial spaces, and into the longitudinal (xylem/phloem) channels in the stele (core) of the root, confirming earlier assessments. We believe these are the first images of a multicellular tissue acquired in vivo exclusively from the intracellular water proton resonance. This method can be further exploited to study water transport in similar systems.