The Effects Of Hydrogen Sulfide And Nitric Oxide On Cadmium Stress And Root Ion Flux In Malus Hupehensis

Cadmium is a kind of heavy metal with strong toxicity and pollution,it is difficult to decompose in soil,easily absorbed and accumulated by roots and can be migrated from the root to the product organ,such as fruit and grain.Nitric oxide and hydrogen sulfide can regulate plant growth and adaptability.Ion flow is the prerequisite for its absorption and accumulation by roots.Based on the research of hydrogen sulfide and nitric oxide alleviating cadmium stress,the change of ionflux in roots was analyzedin Malus hupehensis treated by H₂ S and NO.The results showed that:1.0.35mmol/L NaHS,which was the H₂S donor in the nutrient solution containing Cd²⁺,could improve the respiration rate of the Malus hupehensis roots,reduce the content of malondialdehyde?MDA?,decrease the rate of chlorophyll degradation and improve the photosynthetic performance,which promoted the efflux of Cd²⁺ in the roots of Malus hupehensis,and inhibited the uptake rate of Cd²⁺,thus reducing the Cd²⁺ content in the roots to a certain extent.The comprehensive analysis showed that the appropriate concentration of H₂ S could alleviate the toxic effects of heavy metal cadmium on the Malus hupehensis seedlings by reducing the absorption of Cd²⁺ of the Malus hupehensis roots.2.50?mol/L SNP,which was the of NO donor in the nutrient solution containing Cd²⁺could increase the respiration rate of the Malus hupehensis roots,reduce the MDA content,decrease the rate of chlorophy ll degradation and improve the photosynthetic performance,which promoted the efflux of Cd²⁺ in the roots of Malus hupehensis and inhibited the uptake rate of Cd²⁺,thus reducing Cd²⁺ content in the roots to a certain extent.The results showed that the proper concentration of NO could alleviate the toxic effect of Cd²⁺ on the seedlings of Malus hupehensis by reducing the absorption of Cd²⁺ by root.3.The addition of 50?mol/L SNP?NO donor?and 0.35mmol/L NaHS?H₂S donor?in the nutrient solution containing Cd²⁺,which could alleviate the ion poisoning effect of Cd²⁺ on seedlings and promote the growth of Malus hupehensis seedlings under Cd²⁺ stress.However,the effect of cotreatment was less than the sum of them.Interestingly,the appropriateconcentration of cPTIO could inhibit their the mitigation effect.Comprehensive analysis shows that the appropriate concentration of NO and H₂ S can reduce the root of the absorption of Cd²⁺ to alleviate the heavy metal cadmium on the Malus hupehensis seedlings toxic effects,and NO inhibitors?cPTIO?can inhibit this effect.4.The effect of H₂S and NO on flow rate of Na⁺ and K⁺ absorption under salt stress of Malus hupehensis,The results showed that salt stress could promote the uptake of Na⁺ and the efflux of K⁺;Nevertheless,NaHS and SNP could promote the efflux of Na⁺ and the uptake of K⁺ in the roots of Malus hupehensis,under salt stress,which reduced the absorption of Na⁺and the efflux of K⁺,and promoted the balance of Na⁺ and K⁺ ions,so as to better maintain the Malus hupehensis growth.