PUB - Publikationen an der Universität Bielefeld

A comparative evaluation of arsenic (As)-induced toxicity has been made in selected Western Himalayan ferns belonging to the family Pteridaceae (Pteris vittataL. andP. creticaL.) and Polypodiaceae (Polypodiodes microrhizoma(C. B. Clarke ex Baker) Ching andLepisorus contortus(H. Chirst) Ching) employing a rapid leaf (pinna) slice test. The exposure of pinna segments to As(V) (Na2HAsO4; 0-1000 mu M), led to a concentration-dependent increase in K(+)leakage into the incubation medium owing to membrane damage. Strong species-specific differences were evident. Thus, the magnitude of K(+)leakage enhancement was much lower in Pteridaceae members (lowest inP. vittata) than in those of Polypodiaceae. The As effects were like those of Cu, a redox active element like As, and H(2)O(2)suggesting them to be mediated by oxidative stress. Involvement of K(+)channels in As-induced K(+)leakage is unlikely, as no effect of tetraethylammonium chloride (TEA), a K(+)channel inhibitor was evident. Furthermore, the activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were markedly altered due to As treatment in a species-specific manner pointing to a role of antioxidant defence in differential response and thereby tolerance of the concerned ferns to As. Findings have implications for phytoremediation.