Assessment of biochemical and physiological tolerance mechanism of the multipurpose paradise tree (Simarouba amara Aubl.) under zinc and copper stress
2022
Kumar, Jatin | Das, Amit K. | Rani, Jyoti | Gupta, Piyush Kumar
Simarouba amara Aubl., commonly known as paradise tree, is a multipurpose, evergreen, poly-gamodioecious, and oil yielding tree. The plant is famous for its seeds containing 55-65% oil, a potent source of biodiesel production and is being utilized in cosmetics, pharmaceuticals, and other industries. The study aimed to evaluate the physiological and biochemical changes that occur in S. amara seedlings under heavy metals stress. Two-month-old S. amara seedlings were exposed to different concentrations of zinc (Zn) and copper (Cu) (Zn and Cu: 10 mg Kg-1, 50 mg Kg-1, 100 mg Kg-1, 200 mg Kg-1). The study indicated that both the heavy metals resulted in a significant decrease in leaf relative water content (LRWC), photosynthetic pigments and an increase in lipid peroxidation and antioxidant levels. Regarding lipid peroxidation, Cu proved to be more toxic to seedlings compared to Zn. However, in terms of LRWC and photosynthetic pigments, Zn showed higher toxic effects than Cu. Proline and cysteine content increased by 234% and 270%, respectively, due to Zn stress and 117% and 102%, respectively, due to Cu stress at 200 mg Kg-1. Among antioxidant enzymes, a maximum increase in glutathione reductase (GR) activity was observed (600% due to Cu stress and 320% due to Zn stress) at 200 mg Kg-1. At the same concentration, a minimum increase was seen in glutathione peroxidase (GPX) activity (60% under Cu stress) and catalase (CAT) activity (69% under Zn stress). The present study revealed that S. amara has a better antioxidant defensive mechanism against oxidative stress and can be used for its large scale cultivation on wastelands.
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