Analysis of Nitrate Absorption and Transport in Non-nodulated and Nodulated Soybean Plants with <SUP>13</SUP>NO<SUB>3</SUB><SUP>-</SUP> and <SUP>15</SUP>NO<SUB>3</SUB><SUP>-</SUP>

Abstract

Nodulating (T202) and non-nodulating (T201) soybean isolines were hydroponically cultivated, then nitrate labeled with 13N or 15N, was added to the culture solution in order to investigate the nitrate absorption and transport in soybean. The accumulation pattern of the absorbed 13N in the first trifoliate was observed by positron emitting tracer imaging system (PETIS) as well as bioimaging analyzer system (BAS). The 15N abundance of each part was determined by emission sjectrometrv.Real time changes in two dimensional image of the radioactivity could be monitored by PETIS, besides the distribution 13N in whole plant could be observed by BAS. However quantitative data were hardly obtained by the 13N analysis. Stable isotope 15N is more reliable in the quantitative analysis in each part. Combing the data obtained by 15N and 13N tracer experiments, the absorption and translocation of N in plant should be more clearly figured out.

Effects of anion channel blockers on xylem nitrate transport in barley seedlings

“…Since NR activities in both shoots and roots were undetectable for the first several hours when nitrate-starved barley plants were exposed to the medium containing nitrate (Somers et al 1983;Melzer et al 1989), the 13N accumulated in the shoots observed in this experiment consisted mostly of i3NO, -which is transported from roots. The results indicated that the radial movement of i3NO) -across the roots, its penetration into the xylem stream and its appearance in the shoots were very rapid, as in the case of soybean and rice plants (Clarkson et al 1996;Hayashi et al 1997;Sato et al 1999). When the distribution of 15N in both shoots and roots was measured with an emission spectrometer, the accumulation in the shoots was very low under the current experimental conditions (data not shown).…”

“…PETIS has been shown to be a useful tool for the detection of two-dimensional and real-time distribution of uN by measuring the amount of )I-rays emitted from positrons without destruction of the plants (Hayashi et al 1997;Kume et al 1997;Sato et al 1999;Kiyomiya et al 2001;Ohtake et al 2001). Since NR activities in both shoots and roots were undetectable for the first several hours when nitrate-starved barley plants were exposed to the medium containing nitrate (Somers et al 1983;Melzer et al 1989), the 13N accumulated in the shoots observed in this experiment consisted mostly of i3NO, -which is transported from roots.…”

“…The solution of 13N03 -was purified by passing it through a cation exchange column and a basic alumina column as described previously (Sato et al 1999;Ohtake et al 2001).…”

“…The 13N accumulation in shoots was monitored using PETIS every minute after the addition of 13N03 -to the medium for 30 min (Sato et al 1999;Ohtake et al 2001). After the measurement by PETIS, barley roots were rinsed three times, for 1 min in three successive 100 mL of deionized water.…”

“…For the measurement of the nitrate flux in intact plants, I3NO]-and 15N03 -were used as tracers. Positron Emitting Tracer Imaging Systems (PETIS) could detect the two-dimensional and real-time distribution of 13N by measuring the amount of 'Y-rays emitted from positrons without destruction of the plant (Hayashi et al 1997;Kume et al 1997;Sato et al 1999;Kiyomiya et al 2001;Ohtake et al 2001). The net nitrate uptake was measured accurately by emission spectrometry using 15N03 -.…”