The effect of osmotics on plant cells: a study using 1H NMR relaxation and self-diffusion of water

The osmotic changes in root cells of Zea mays L. under the effect of mannitol (concentration range 1-15%; range of osmotic pressures: -0.13 to -2.01 MPa) were studied by measuring time and concentration dependence of water self-diffusion constant (Deff) and proton spin-lattice relaxation time (T1) using proton NMR relaxation spectroscopy. In addition, in vivo uptake of Mn2+ by roots after their incubation in mannitol solutions were studied. At low (less than or equal to 5%) and medium (5-10%) concentrations of the osmoticum dehydration takes place proportional to the concentration, whereas membrane destruction occurs at higher concentrations (10-15%). It seems that there is a distribution of cells within root tissue regarding their sensitivity to osmotic stress.