MEASURING NITRATE IN PLANT-CELLS BY IN-VIVO NMR USING GD3-REAGENT( ASA SHIFT)

NMR investigations of nitrate in plant cells and tissues have hitherto been limited by the indistinguishability of the signals from intracel lular and extracellular nitrate. Gd3+ is shown to be an effective shif t reagent for N-14 and N-15 nitrate NMR signals, resolving the interna l and external nitrate signals in plant tissues, including cell suspen sions and root material. However, time-course experiments show that, w hile the use of Gd3+ allows nitrate levels to be monitored over extend ed periods, it also has adverse effects on growth and nitrate uptake. Accordingly, a number of chelated forms of gadolinium were investigate d, and it is concluded that the NMR contrast agent Gd(DTPA-BMA) is lik ely to be a suitable shift reagent for physiologically relevant studie s of nitrate transport in roots. (C) 1996 Academic Press, Inc.