Effects of lead on the activities of stress related enzymes, contents of mineral and chlorophyll, and growth in Nasturtium officinale R. Br.

ABSTRACTPhD THESISEFFECTS OF LEAD ON THE ACTIVITIES OF STRESS RELATEDENZYMES, CONTENTS OF MINERAL AND CHLOROPHYLL, ANDGROWTH IN Nasturtium officinale R. Br.Gonca KESERUNIVERSITY OF ÇUKUROVAINSTITUTE OF NATURAL AND APPLIED SCIENCESDEPARTMENT OF BIOLOGYSupervisor: Assoc. Prof. Dr. Saadet SAYGIDEĞERYear: 2005, Page: 95Jury: Assoc. Prof. Dr. Saadet SAYGIDEĞERAssoc. Prof. Dr. Oya IŞIKAssoc. Prof. Dr. H. Yıldız DAŞGANAsisst. Prof. Dr. Elif ORUÇAsisst. Prof. Dr. Nisa ÜNALDI CORALIn the present study, Nasturtium officinale R. Br. collected from natural environment,was treated with different lead concentrations (0, 25, 50, 100, 200, 250 and 500 ppm)for 14-days in controlled conditions. At the end of the treatment period, contents ofphotosynthetic pigments, contents of water, lipid peroxidation, amounts of Mn, Cu,Mg, Ca, Zn, Fe, Pb and antioxidant enzymes superoxide dismutase (SOD),glutathione reductase (GR), ascorbat peroxidase (AP) and catalase (CAT) weredetermined. Pb amounts in stems and leaves of N. officinale were increased withapplied metal concentrations. The increase was determined at photosyntheticpigment contents in leave tissues of N. officinale treated with low Pb concentrations(25-50 ppm), while high Pb concentrations (200-500 ppm) resulted in decrease. Thewater content decreased in the roots, stem and leaves with an increace in Pb supply.The amounts of Mn and Cu were decreased in the stem and leaves at 200, 250 and500 ppm Pb concentrations. Higher concentration of lead (250-500 ppm) has beenattributed to increased amounts of Ca and Fe, while the amounts of Mg wasdecreased. The tissue concentration of Pb increased with an increasing level ofsupply. Lead treated plants showed incread levels of lipid peroxidation as evidencedfrom the increased malondialdehyde content in leaves. Lead stress caused significantchanges in the activity of antioxidative anzymes. Activities of SOD, AP, CAT, GRwere decreased in the stems at 500 ppm Pb concentrations. The results indicate that atoxic concentration of lead 500 ppm and Pb toxicity induce oxidative stress anddifferential responses of antioxidant enzymes in plant parts.Key words: Nasturtium officinale, lead, antioxidant enzymes, lipid peroxidation,growth.II