Induction of Low Molecular Weight Cadmium-Binding Compound in Soybean Roots

Blakeley, S. D., Robaglia, C, Brzezinski, R. and Thirion, J-P.1986. Induction oflow molecular weight cadmium-binding compoundin soybean roots.—J. exp. Bot. 37: 956–964. A Cd-binding compound has been identified in roots of Cd-treatedsoybean plants (Glycine max L.). Induction of synthesis of thiscompound after treatment with CdCl₂ was monitored by labellingwith either ¹⁰⁹Cd in vitro or with ³⁵S-cysteine or ³⁵S-methioninein vivo. The apparent molecular weight as determined by gelfiltration was about 14000 daltons. However, after carboxymethylationand electrophoresis under denaturing conditions its molecularweight was less than 3400 daltons. Simultaneous labelling with¹⁰⁹ and ³⁵S-cysteine demonstrated that the compound containscysteine residues. Gel electrophoresis of ³⁵S-cysteine or ³⁵S-methioninelabelled protein samples showed the compound to be rich in cysteinebut not in methionine, and that it was induced about 60-foldby 1?0 mol m^–3 CdCl₂ after 7 d. Key words: Soybean, cadmium, induction, root