Excess Nickel Modulates Oxidative Stress Responsive Enzymes in Groundnut

Abstract

Groundnut plants exposed to excess nickel (Ni) produced visual symptoms of toxicity that intensified with increasing level and duration of metal supply. Decreased concentrations of pigments along with a marked increase in the activities of anti-oxidative enzymes such as superoxide dismutase, ascorbate peroxidase, and peroxidase suggest strong induction of oxidative stress due to excess Ni. The decreased activity of catalase may suggest interference of excess nickel in iron metabolism of plants. The appearance of metal specific toxicity is a likely result of damage predominantly due to enhanced generation of reactive oxygen species (ROS) at higher (300–400 μM) nickel supply. The threshold of toxicity (10% growth reduction) and toxicity (33% growth reduction) values of Ni in groundnut were 26 and 72 μg g⁻¹ in leaves, 17 and 94 μg g⁻¹ in stem and 45 and 240 μg g⁻¹ in roots respectively.

Keywords:

• groundnut
• nickel
• pigments
• oxidative stress
• threshold values