Tracing Effects of Na+ on Morphology, Phosphate Metabolism and Accumulated Compounds of a Sugar Beet Root by NMR

Abstract

Effects of Na+ on morphology, phosphate metabolism and accumulated compounds of sugar beet root were studied by 'H-NMR imaging, and 31P-, 23Na- and 13C NMR. 23Na NMR showed that Na+ concentration of the sugar beet root reached 9.2 mM in the medium containing 180 mM NaCl. Broadening of 31P NMR signal of vacuole-associated inorganic phosphate upon addition of Na+ suggests that the sugar beet root cells are furnished with the mechanism that alleviates the injurious effect of Na+. Strong water signal was observed in epidermal and vicinal cells, and around vascular bundles in 'H-NMR images, which was reduced by Na+ treatment. Based on 'H-NMR images and pictures of tetranitro blue tetrazolium (TNBT) staining, water was located in tissues with metabolically active cells. 13C NMR spectra of 80% ethanol extracts of sugar beet roots showed accumulation of sucrose, betaine and glutamine. Extra accumulation of sucrose and betaine in parenchyma cells by Na+ treatment resulted in the reduction of active cells. Since Na+ treatment suppressed enlargement of sugar beet roots, the plant did not acquire resistance to grow against strong salt stress by long-term acclimation, though the results of this investigation showed that the plant is, by nature, tolerant to salt stress. © 1993, CROP SCIENCE SOCIETY OF JAPAN. All rights reserved.