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Seedlings growth and antioxidative enzymes activities in leaves under heavy metal stress differ between two desert plants: a perennial (Peganum harmala) and an annual (Halogeton glomeratus) grass
- Lu, Yan, Li, Xinrong, He, Mingzhu, Zhao, Xin, Liu, Yubing, Cui, Yan, Pan, Yanxia, Tan, Huijuan
- Acta physiologiae plantarum 2010 v.32 no.3 pp. 583-590
- Halogeton glomeratus, Peganum harmala, antioxidant activity, ascorbate peroxidase, catalase, grasses, heavy metals, hydrogen peroxide, leaves, metal tolerance, oxidative stress, seedling growth, seedlings, superoxide dismutase, toxicity testing, xerophytes
- The present study showed the toxicity caused by heavy metal and its detoxification responses in two desert plants: perennial Peganum harmala and annual Halogeton glomeratus. In pot experiments, 1-month-old seedlings were grown under control and three levels of combined heavy metal stress. Seedling growth as well as heavy metal accumulation, antioxidative enzymes [superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX)] activities and the contents of malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) in leaves was examined after 2 months of heavy metal exposure. Compared with H. glomeratus, growth of P. harmala was more severely inhibited. In leaves, the heavy metal accumulation pattern in both the plants was dose-dependent, being more in H. glomeratus. H. glomeratus exhibited a typical antioxidative defense mechanism, as evidenced by the elevated activities of all the three enzymes tested. P. harmala exhibited a different enzyme response pattern, with a significant reduction in CAT activity, and elevated SOD and APX activities, but significantly elevated APX activity was only at the lowest heavy metal concentration. MDA and H₂O₂ contents were significantly enhanced in leaves of heavy metal-treated P. harmala, but in H. glomeratus were elevated only at the highest heavy metal treatment. These results indicated that H. glomeratus had a greater capacity than P. harmala to adapt to oxidative stress caused by heavy metal stress, and antioxidative defense in H. glomeratus might play an important role in heavy metal tolerance.