Arsenic-induced changes in growth and antioxidant metabolism of fenugreek

作者：Talukdar Dibyendu^*

来源：Russian Journal of Plant Physiology, 2013, 60(5): 652-660.

DOI：10.1134/S1021443713050130

• Trigonella foenum-graecum
• arsenic
• hydrogen peroxide
• antioxidant defense
• isozymes
• growth
• oxidative stress

The effects of arsenic (As) on growth and antioxidant metabolism of fenugreek (Trigonella foenum-graecum L. cv. Azad) plants were studied using 10, 20, and 30 mg As/kg of soil in a pot experiment under controlled conditions. The length and dry weights of shoots and roots, photosynthetic traits, and grain yield components exhibited a significant increase over control (0 mg As/kg) at As-20 but decreased markedly at As-30. The cause of this completely reverse response of plant growth between As-20 and As-30 was investigated in the backdrop of H2O2 metabolism by analyzing responses of three prominent antioxidant enzymes, namely superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) along with cellular ascorbate pool and its redox state. Despite a significant increase in the H2O2 content in both As-20 and As-30 plants, the former, unlike As-30 plants, did not experience any type of As-induced oxidative stress (membrane lipid peroxidation, electrolyte leakage). Normal to high levels of leaf APX, CAT, and redox pool of ascorbate effectively balanced the elevated SOD activity at As-20, maintaining the H2O2 concentration higher than control but obviously in favor of As-20 plant growth. By contrast, soil amendment with phosphorus (200 mg P/kg) at As-30 prevented As-induced oxidative stress through the reduction of the H2O2 level even below As0. The increased enzyme activity was mainly due to the induction of unique Cu/Zn, Fe, and Mn isoforms of SOD and APX-3/APX-4 and/or their increased expression in coordination with CAT. The detection of novel isoforms suggests a strong response of H2O2-metabolizing enzymes against As-induced oxidative stress in fenugreek.

• 出版日期2013-9