Protective roles of nitric oxide on seed germination and seedling growth of rice (Oryza sativa L.) under cadmium stress

Published Date

October 2014, Vol.108:114–119, doi:10.1016/j.ecoenv.2014.05.021

Title 

Protective roles of nitric oxide on seed germination and seedling growth of rice (Oryza sativa L.) under cadmium stress

• Author 

• Junyu He ^,
• Yanfang Ren
• Xiulan Chen
• Hui Chen

• College of Agriculture, Guizhou University, Guiyang 550025, China

Received 8 August 2013. Revised 6 April 2014. Accepted 19 May 2014. Available online 19 July 2014.

Highlights

• •
  SNP attenuated the Cd-induced inhibition of rice seed germination and seedling growth.
• •
  The maximum alleviation is obtained with the application of 30 μM SNP.
• •
  The antioxidant enzymes׳ activity is enhanced by 30 μM SNP under Cd stress.
• •
  30 μM SNP strongly reduced Cd accumulation in rice seedlings.

Abstract

Nitric oxide (NO) is a bioactive molecule in plants which mediates a variety of physiological processes and responses to biotic and abiotic stresses including heavy metals. In the present study, the effects of exogenous NO donor sodium nitroprusside (SNP) on rice seed germination and seedlings growth were investigated under Cd stress and a possible mechanism was postulated. The results indicated that 100 μM Cd significantly decreased rice seed germination index, vigor index, root and shoot lengths as well as fresh weight compared to control. Exogenous SNP dose-dependently attenuated the inhibition of rice seed germination and thereafter seedling growth caused by Cd. The promoting effect was most pronounced at 30 μM SNP. Cd exposure caused oxidative stress by elevating hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) contents in root and shoot of rice seedlings. 30 μM SNP counteracted partly Cd toxicity by reducing the H₂O₂ and MDA contents of Cd-exposed seedlings. Meanwhile, application of SNP markedly stimulated the activities of superoxide dismutases (SOD), ascorbate peroxidases (APX), guaiacol peroxidase (POD) and catalases (CAT) compared with Cd treatment alone, thereby indicating the enhancement of the antioxidative capacity in the root and shoot under Cd stress. In addition, addition of 30 μM SNP increased accumulation of proline in both root and shoot. The Cd accumulation in seedlings was significant reduced by SNP, implicating that the protective role of SNP was responsible for preventing Cd accumulation. However, the effects of SNP were reverted by addition of cPTIO, a NO scavenger, suggesting the protective roles of SNP might be related to the induction of NO. Furthermore, K₃Fe(CN)₆ and  /  had no similar roles as SNP. Based on these results, it can be concluded that SNP exerted an advantageous effect on alleviating the inhibitory effect of Cd on rice seed germination and seedling growth, which might interact with NO.

Keywords

• Cadmium
• Rice
• Seed germination
• Nitric oxide
• Antioxidative enzymes

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• ⁎ 
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