Root absorption and transport behavior of technetium in soybean [Glycine max]

• Published in: Plant physiology (Bethesda) 1983-11, Vol.73 (3), p.849-852
• Main Authors: CATALDO, D. A, WILDUNG, R. E, GARLAND, T. R
• Format: Article
• Language: English
• Subjects: Anions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Glycine max; Kinetics; Phosphates; Plant nutrition; Plant physiology and development; Plant roots; Plants; roots; Seedlings; Soil pollution; Sulfates; technetium -99; Water and solutes. Absorption, translocation and permeability
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.73.3.849

The absorption characteristics and mechanisms of pertechnetate ($\text{TcO}_{4}{}^{-}$) 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 $\text{TcO}_{4}{}^{-}$ being transferred to the shoot. Evaluation of concentration-dependent absorption rates from solutions containing 0.02 to 10 micromolar $\text{TcO}_{4}{}^{-}$ shows the presence of multiphasic absorption isotherms with calculated $\text{K}_{s}$ values of 0.09, 8.9, and 54 micromolar for intact seedlings. The uptake of $\text{TcO}_{4}{}^{-}$ 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 $\text{TcO}_{4}{}^{-}$ and inhibiting anions show permanganate to be a noncompetitive inhibitor, while sulfate, phosphate, and selenate, and molybdate exhibit characteristics of competitive inhibitors of $\text{TcO}_{4}{}^{-}$ transport suggesting involvement of a common transport process.