Effects Of Hydrogen Sulfide On Cucumber Germination And Peroxidation Damage Induced By Salinity And Cadmium Stress

Hydrogen sulfide, as a biological toxic gas in many industrial waste, was proved to be animportant role in controlling the metabolism of animals and plants in recent studies. H₂S hasbeen reported as a signaling molecule in plants, but not much. In this paper, effect of sodiumhydrosulfide （NaHS）, a H₂S donor, on the cucumber seed germination under salt andcadmium stress was studied, and its possible physiological and biochemical regulationmechanism was researched. the main results as follows:1. Sodium hydrosulfide （NaHS）, a H₂S donor, can improve the cucumber seedgermination rate, enhance the antioxidant capacity of the cucumber hypocotyls and radicles,and effectively alleviate the oxidative damage under NaCl stress. NaCl treatment significantlyinduced accumulation of H2O2and MDA in cucumber hypocotyls and radicles, andapplication of NaHS dramatically reduced the accumulation of H2O2and lipid peroxidation.At the same time, the amylase activities in cotyledons were increased, and the length ofcucumber hypocotyls and radicles were significant promoted by NaHS treatment under NaClstress. However, the alleviating effects greatly depended on the concentrations of NaHS, and400μmol·L^-1NaHS treatment showed the most significant effects. Unlike the effects of NaHS,pretreatment with other sodium salts including Na₂S, Na₂SO₄,NaHSO₄, Na₂SO₃, NaHSO₃andNaAc did not show significant effects on the growth of cucumber hypocotyls and radicles.These salts do not release H₂S. Based on above results, it can be concluded that the effects ofNaHS in the experiment depended on the H₂S rather than other compounds derived fromNaHS.2. Effects of sodium hydrosulfide （NaHS）, a H₂S donor, on the cucumber seedgermination rate and the the antioxidant capacity of cucumber hypocotyls and radicles wereimproved under cadmium stress. The inhibited growth of cucumber hypocotyls and radiclesby cadmium was alleviated by different concentrations(300μmol·L^-1,600μmol·L^-1,900μmol·L^-1,1200μmol·L^-1)of NaHS treatment, especially under the900μmol·L^-1treatment.NaHS treatment significantly increased activities of amylase, SOD, POD, CAT and APX aswell as the capacity of α, α-diphenyl-β-picrylhydrazyl radical（DPPH）and hydroxylradical（OH）scavenging in both hypocotyls and radicles of cucumber, as the results, theaccumulations of MDA and H2O2were decreased. Otherwise, the treatments with othersodium salt including Na₂S, Na₂SO₄, NaHSO₄, Na₂SO₃, NaHSO₃and NaAc had nosignificant effects on the growth of cucumber hypocotyls and radicles. Based on these results,it could be concluded that the function of NaHS was attributed to H₂S from it.