Physiological effects of nitric oxide on the growth and development of wheat roots under cadmium stress

To study the role of sodium nitroprusside (SNP,a donor of nitric oxide (NO)) in alleviating cadmium (Cd) toxicity in wheat (Triticum aestivum L.),wheat seedlings exposed to 10 mmol/L Cd²⁺ as CdCl₂ were treated with 30 μmol/L of SNP.Results showed that Cd²⁺ exposure depressed plant growth.After SNP application,the length,fresh weight,and dry weight of the roots increased by 48%,107.7%,and 87.3% respectively.In addition,SOD,POD,CAT,and APX increased by 28.5%,7.4%,19.2%,and 9.8%,respectively.The contents of O₂^.- and H₂O₂ in the roots decreased by 80.5% and 47.0%,respectively,whereas the contents of soluble sugar and proline increased by 24.7% and 22.1%,respectively.The content of MDA in the roots decreased by 30.2% under Cd²⁺ stress.Root activity increased by 15.3% under Cd²⁺ stress after the addition of SNP.Therefore,exogenous SNP significantly improved the antioxidant capacity of wheat roots,which could,in turn,enhance the resistance ability of wheat and alleviate the toxic effects of Cd.Furthermore,SNP could promote the growth and development of wheat seedling roots.