The Expression Of Heavy Metal Metabolism Gene Responsive To Manganese And Cadmium Stress In Phytolacca Americana L.

Mn is necessary microelement of plants, but it will stress and poison plants if the concentration ofMn is too high. Now Mn is one of the main source of heavy metal pollution in most acid soil in ourcountry. Cd is the poisonous element of plants growth and also the strongest mobility in heavy metals.In-situ remediation of soil that is contaminated by Mn and Cd through using hyperaccumμlator is thehot spot of environmental biotechnology. Phytolacca americana L. is the earliest discovered one ofmanganese and cadmium hyperaccumμlation plants. But currently molecμlar mechanism research ofcadmium and manganese is less in hyperaccumμlation Phytolacca americana L., which restrictsapplication of this plant in the field of heavy metal pollution repairmen. In this research, we got a YS3gene fragment that is related to transmembrane transport of heavy metals in plants and a CS genefragment that is related to cross-organizational transshipment of heavy metals in plants by homologycloning from Phytolacca americana L.. We analysed differential expression of YS3gene, CS gene andMT gene which is related to detoxication of heavy metal by qRT-PCR in roots and leaves of plant tissue,for tissue localization of genes relating to heavy metal in plants. We got samples that were treated indifferent concentration nutrient solution concluding Mn and Cd, and then we analysed the expressionquantity of YS3gene, CS gene and MT gene by qRT-PCR in samples for confirming the response ofgenes relating to Mn and Cd stress.The resμlt of homology cloning showed that we get a fragment of YS3gene which is275bp andencoding91aa. DNA sequence homology of this gene is79%compared with Malus xiaojinensis andamino acid sequence homology of this gene is93%compared with Theobroma cacao. We also get afragment of CS gene which is178bp and encoding58aa. DNA sequence homology of this gene is85%compared with Beta Vμlgaris and amino acid sequence homology of this gene is95%compared withMalus xiaojinensis.The resμlt of tissue localization showed that YS3gene, CS gene and MT gene expressed in rootsand leaves of Phytolacca americana L., but expression quantity in roots is more than in leaves. Theexpression quantity of three genes are1.27times,1.06times and1.67times in roots than leaves at thesame time.The resμlt of gene expression responsing to stress showed that YS3gene, CS gene and MT gene areresponsed to Mn, Cd stress in roots and leaves in Phytolacca americana L.. The detailed resμlts asfollows: the expression of YS3increased first and then reduced as time past in each concentration of Cdand Mn treatments in leaves. The maximum comes at12h. The expression of YS3in roots is the same asin leaves with high concentration of Cd and each concentration of Mn, but it follows high-low-highpattern in roots under low concentration of Cd stress. It shows that YS3gene coμld express sharply byinducing under Cd and Mn stress.The expression of MT in leaves follows high-low-high pattern with each concentration of Cd stress,the maximum comes at12h; the expression of MT in low concentration of Mn treatments is the same as Cd treatment, however, it follows continued-increased pattern in high concentration of Mn stress and themaximum comes at36h. In roots, the expression of MT continue-increased first and then reduced astime past in each concentration of Cd and Mn treatments. The maximum comes at24h in roots. It showsthat MT gene coμld express sharply by inducing under Cd and Mn stress.The expression of CS in leaves follows high-low-high pattern with low concentration of Cd stressin leaves and the maximum comes at12h, however, it is just decreased in high concentration of Cdstress; the expression of CS increased first and then reduced as time past in low concentration of Mntreatments in leaves and the maximum comes at12h, but it follows continuely increased pattern and themaximum comes at36h. Among roots, the expression of CS increased first and then reduced as timepast in each concentration of Cd and Mn treatments, and the maximum comes at24h. It shows that CSgene coμld express sharply by inducing under low concentration of Cd and all concentrations of Mnstress in leaves and roots, however, it is restrained by high concentration of Cd stress in leaves.