Abstract

To investigate the effect of exogenous Nitric oxide (NO) on submerged plants,Hydrilla verticillata (L.f.) Royle was treated with 25 - 400 μΜ sodium nitroprusside (SNP, a NO donor) for 0.5 - 4 d. The alterations in plant growth, H₂O₂, total chlorophyll and malondialdehyde (MDA) content and the antioxidant response were assayed. The results showed that 25 - 100 μΜ SNP increased the plant growth and total chlorophyll content and reduced the level of H₂O₂. However, an increase in H₂O₂ and MDA content and a decrease in total chlorophyll were detected in plants exposed to 200 - 400 μΜ SNP. The activity of catalase and peroxidase decreased in plants exposed to 25 - 400 μΜ SNP; and for superoxide dismutase, its activity was suppressed by the 25 and 50 μM SNP. The content of ascorbic acid and dehydroascorbate were also determined. The results provided the evidence that 25 - 100 μM SNP increased the growth of H. verticillata by alleviating the oxidative stress and 200 - 400 μM SNP might enhance the oxidative stress in plant cell. The results suggested that NO has dual role on the growth and ROS metabolism ofHydrilla verticillata (L.f.) Royle.

Key words: Nitric oxide, Hydrilla verticillata (L.f.) Royle, chlorophyll, growth, malondialdehyde.

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