Figure 2.

Steady-state Cd²⁺ fluxes in non-mycorrhizal (NM) Populus × canescens and ectomycorrhizal (EM) roots under cadmium and salt stress. Poplar plantlets inoculated with or without Paxillus involutus isolates (MAJ or NAU, 30 d), were hydroponically acclimated and subjected to 24 h of CdCl₂ (0 or 50 μM) in combination with NaCl (0 or 100 mM). Root tips were excised from EM- and NM-poplars and equilibrated for 30 min in measuring solution. Net fluxes of Cd²⁺ along root axis (100 to 2300 μm) were monitored at an interval of 200–300 μm (Figure S1). Mean values of Cd²⁺ fluxes in control (−Cd), CdCl₂ stress (+Cd), and combined stress of CdCl₂ and NaCl (+Cd + NaCl) are shown. Cd²⁺ flux was not detectable in salt controls that were treated without CdCl₂. Each column is mean ± SD obtained from 5 individual plants. Statistically significant differences (p < 0.05) among treatments are indicated with different letters (a–e).