Characterization Of Nicotiana Tabacum NtGSH2 And NtPCS1 Genes And Their Responses To Cadmium And Zinc Stress

In higher plants,heavy metals detoxification is completed through complexation and compartmentalization,where glutathione synthase and phytochelatin synthase are critical enzymes.In this work,NtGSH2 and NtPCS1 genes were cloned from Nicotiana tabacum to investigate their molecular characteristics by sequence alignment,tissue expression patterns and heavy metal induced expression analysis.In addition,the biological function of NtPCS1 was explored by heterologous expression in Arabidopsis and overexpression in tobaccos.The results showed as follows:?1?Sequence of GSH2 proteins and N-terminal domain of PCS proteins are highly conserved from different species.?2?NtGSH2 and NtPCS1 genes were expressed in root,stem,leaf,flower and seed of tobaccos,with the strongest expression in flower.?3?The transcriptional expression of NtGSH2 and NtPCS1 genes were up-regulated by Cd²⁺ and Zn²⁺.?4?NtPCS1 gene encoded a phytochelatin synthase protein,and enzyme activity was increased by Ag²⁺ and Cd²⁺.?5?Arabidopsis Atpcs1 mutants enhanced Cd²⁺ tolerance remarkably by heterologous expression of NtPCS1 gene.?6?Overexpression of NtPCS1 gene lead to Cd²⁺ hypersensitivity in tobaccos.?7?Overexpression of NtPCS1 gene lead to more PCs accumulation in tobaccos.?8?Exogenous GSH lead to decreased Cd²⁺ hypersensitivity of transgenic tobaccos overexpressing NtPCS1 gene.?9?Exogenous GSH lead to more Cd²⁺ and Zn²⁺ accumulation in transgenic tobaccos overexpressing NtPCS1 gene.