Root Absorption and Transport Behavior of Technetium in Soybean 1

• Published in: Plant physiology (Bethesda) Vol. 73; no. 3; pp. 849 - 852
• Main Authors: Cataldo, Dominic A., Wildung, Raymond E., Garland, Thomas R.
• Format: Journal Article
• Language: English
• Published: 01-11-1983
• ISSN: 0032-0889; 1532-2548

The absorption characteristics and mechanisms of pertechnetate (TcO
4
−
) uptake by hydroponically grown soybean seedlings (
Glycine max
cv Williams) were determined. Absorption from 10 micromolar solutions was linear for at least 6 hours, with 30% of the absorbed TcO
4
−
being transferred to the shoot. Evaluation of concentration-dependent absorption rates from solutions containing 0.02 to 10 micromolar TcO
4
−
shows the presence of multiphasic absorption isotherms with calculated K
s
values of 0.09, 8.9, and 54 micromolar for intact seedlings. The uptake of TcO
4
−
was inhibited by a 4-fold concentration excess of sulfate, phosphate, selenate, molybdate, and permanganate; no reduction was noted with borate, nitrate, tungstate, perrhenate, iodate, or vanadate. Analyses of the kinetics of interaction between TcO
4
−
and inhibiting anions show permanganate to be a noncompetitive inhibitor, while sulfate, phosphate, and selenate, and molybdate exhibit characteristics of competitive inhibitors of TcO
4
−
transport suggesting involvement of a common transport process.