Accumulation and translocation of Cd metal and the Cd-induced production of glutathione and phytochelatins in Vicia faba L.

Abstract

Translocation of cadmium (Cd) in the tissues of Vicia faba, the water content in biomass, the biomass production, and the glutathione and phytochelatin tissue concentrations were studied and correlated with the plant sensitivity and/or tolerance to Cd. The total concentrations of Cd were determined by inductively coupled plasma/mass spectrometry (ICP-MS), the concentrations of glutathione (GSH) and phytochelatins 2 and 3 (PC2 and PC3) were determined by on-line high performance liquid chromatography/electrospray-ionization tandem mass spectrometry (HPLC–ESI–MS–MS) in the roots and leaves of the sensitive and the tolerant cultivars of V. faba grown in Cd containing nutrient solutions (NS, 0–100 μmol l−1 Cd2+). Both the cultivars of V. faba accumulate a major portion of Cd in the roots and only a minor part of ca. 4% in the leaves. The differences between the cultivars concerning Cd accumulation in leaves were apparent from higher Cd concentrations in NS and the Cd amount in the sensitive cultivar was approximately twice as high. In the roots, the differences between the cultivars in the Cd accumulation were only statistically significant with the highest Cd concentrations in NS, with the tolerant cultivar accumulating about 16% more of Cd compared to the sensitive one. The biomass production of the sensitive cultivar decreased approximately twice as fast with increasing Cd concentration in NS. The biomass water content decreased with increasing Cd concentration in NS in both the cultivars. In general, the GSH concentration did not linearly correlate with Cd accumulation, except for the roots of the sensitive cultivar where it was independent, and was higher in the sensitive cultivar than in the tolerant one in both the leaves and roots. The GSH concentration in leaves was approximately one order of magnitude higher than that in the roots for both the cultivars. The relationships between the PC and Cd concentrations in tissues were found nonlinear. At lower Cd accumulation levels, the PC concentrations followed an increase in the Cd accumulation in both the roots and leaves, whereas at higher Cd accumulations the relations differed between roots and leaves. In the roots, the PC concentrations decreased with increasing Cd accumulation, whereas the PC concentration in the leaves followed the decrease in the Cd accumulation.