NMR investigations of nitrate in plant cells and tissues have
In fact, severe quadrupolar broadening restricts the applicahitherto been limited by the indistinguishability of the signals from tion of in vivo 35 Cl NMR to the detection of chloride in intracellular and extracellular nitrate. Gd 3/ is shown to be an compartments, such as plant cell vacuoles, with low protein effective shift reagent for 14 N and 15 N nitrate NMR signals, resolvcontent. In contrast, the 14 N and 15 N NMR signals from tissue ing the internal and external nitrate signals in plant tissues, includnitrate are fully detectable, and a shift reagent for nitrate ing cell suspensions and root material. However, time-course exwould be expected to facilitate nitrate transport studies in periments show that, while the use of Gd 3/ allows nitrate levels microorganisms and plant tissues.
to be monitored over extended periods, it also has adverse effects
Nitrate is an important source of nitrogen for many plants, on growth and nitrate uptake. Accordingly, a number of chelated and nitrate uptake and storage are important phenomena (4).
forms of gadolinium were investigated, and it is concluded that
The main techniques currently available used for studying the NMR contrast agent Gd(DTPA-BMA) is likely to be a suitable shift reagent for physiologically relevant studies of nitrate trans-these processes are 13 N and 15 N tracer methods (5, 6) (which port in roots.