Fig. 1.

Sulphur metabolite contents and ³⁵S flux into different metabolite pools of OAS-treated poplar roots. Excised fine roots from poplar trees were pre-treated without (A, n=12) or with 1 mM OAS (B, n=12) for 2 h and subsequently exposed to [³⁵S]sulphate plus 1 mM OAS for 4 h for sulphate uptake and ³⁵S flux measurements. Sulphate (μmol g⁻¹ FW), GSH (nmol g⁻¹ FW), and protein (mg g⁻¹ FW) contents were determined (pink squares). ³⁵S flux into internal sulphate, GSH, and protein is given as pmol ³⁵S g⁻¹ FW h⁻¹ (light blue squares). APR activity is indicated in a green square as nmol mg⁻¹ protein min⁻¹. Significant differences at P <0.05 from control roots without OAS are indicated by asterisks.