Toxic effects of cadmium on growth of Aloe ferox Mill

Heavy metals like cadmium (Cd) are a serious threat for living organisms due to increased global environmental pollution. Aloe ferox Mill. is a very important species of the genus Aloe, especially from a medical point of view, because it is a source of biologically active substances and it is often used in the traditional medicine. Since the knowledge about the effect of heavy metals, like Cd on growth of Aloe species is scarce, this study showed the effect of Cd on anatomical, morphological and physiological properties of this important medicinal plant species. We found that Cd affected the leaf morphology and decreased biomass of the aboveground plant part. Cd also affected cuticle deposition and increased the number of stomata in the abaxial and adaxial epidermis of leaves. Roots treated with Cd showed lower lignification and decreased level of membrane lipids peroxidation than control roots. Cadmium concentration was the highest in the roots; however, relatively high portion of Cd is being translocated to the leaves. This might be dangerous as Aloe is well known medicinal plant with content of active secondary metabolites mainly in the leaves.