Effect And Regulaion Of Sulfur On Arsenic Tolerance Of Wheat Seedlings

Arsenic（A_s）is carcinogenic to humans.Arsenic in the environment can result in potential health risk to humans through food chain.It is very important to study the alleviation of sulfur（S）on A_s toxicity to wheat（Triticum aestivum L.）seedlings.Hydroponic cultures were conducted to study the effect of S and L-buthionine sulphoximiine（BSO）on the growth,cell membrane permeability and A_s accummulation in wheat seedlings exposed to A_s.Glutathione（GSIH）and phytochelatins（PC_s）in roots of wheat seedlings were also studied.The results showed that the relative root elongation of wheat seedlings decreased with increasing A_s（Ⅲ、Ⅴ）concentrations.Under 4 μmol L-1 A_s（Ⅲ）stress,2 mmol L"1 S（Na₂SO₄）significantly alleviated A_s toxicity to wheat seedlings,while under 4 μnol L-1 A_s（V）,A_s toxicity to wheat seedlings was not significantly alleviated untile S concentration increased to 6 mmol L-1.The supply of S increased the RRE（relative root elongation）,root activities,concentrations of GSH,PCs and A_s in roots of wheat.The relative conductivity,A_s concentrations in the shoots of wheat seedlings and translocation factor（TF）of A_s reduced by S.BSO（0.5 mmol L-1）significantly decreased the RRE,root activities,concentrations of GSH,PCs and A_s in roots of wheat seedlings,but increased the relative conductivity of roots under A_s exposure.The induced synthesis of NPT may be one of the important reasons that S alleviate A_s toxicity of wheat seedlings.