Fig. 5.

Sulphur metabolite contents and ³⁵S flux into different metabolite pools of fine roots from poplar plants overexpressing bacterial γ-ECS. Excised fine roots from the WT (A, n=6) and from transgenic poplar lines overexpressing γ-ECS targeted into either the cytosol (B, n=3) or plastids (C, n=11) were selected. Roots were exposed to [³⁵S]sulphate for 4 h to measure sulphate uptake and ³⁵S flux into different metabolite pools. 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 between WT and transgenic poplar roots at P <0.05 are indicated by asterisks.