Distribution of cadmium in shoot and root tissues of maize and pea plants: Physiological disturbances

Maize and pea plants were treated with 0.0 (control), 0.01 or 0.05 mM Cd in the growing medium for 11 d. Although the total Cd concentration was similar in shoot and root tissues of both species, pea plants showed more severe toxic symptoms. The fresh weight and percentage of water content of root and shoot decreased concomitantly to Cd supply. High Cd levels were found in the cell-wall fraction (Fraction I) and in Fraction IV (soluble) of maize plants, whereas Cd-treated pea accumulated more Cd in the soluble fraction. The protein concentration of Fraction IV of pea shoot and root significantly increased upon treatment with 0.05 mM Cd, whereas maize showed no effect. Furthermore, a previously not visible protein (similar to 12 kDa), appeared in Fraction IV of pea root grown with the highest Cd supply. Cadmium treatment, in general, notably enhanced the concentrations of 2-thiobarbituric acid reactive material (lipid peroxidation products) in pea fractions, presumably due to Cd-induced oxidative stress.