Study On Pb-Zn Accumulation Characteristics And The Expression Of Glutathione In Carex Putuoshanensis Sp. And Carex Evergold

In this paper,based on previous experiments,the lead(Pb)hyperaccumulation Carex putuoshanensis sp.and the Pb accumulator plant Carex evergold had been selected to study the plant growth,heavy meatal acculmulation characteristic,Therein,the single treatment of Zn was 125 mg/L,the single treatment of Pb was 600 mg/L and the combination of heavy metal was Pb 600 mg/L,Zn 125 mg/L with CK as control.This study was conducted to provide the theoretical reference materials and discuss the reaction mechanism of heavy metal stress in plants.The main conclusions are as follows:(1)Pb,Zn,Pb+Zn stress had effect on the Pb and Zn contents of Carex putuoshanensis sp.and Carex evergold,the contents of Pb / Zn were higher than that of control at different growth stage.Compared with the control group,the increments of Pb and Zn content in the two species in flowering stage were higher which indicated flowering stage was the sensitive stage on Pb-Zn stress.In different treatments during the flowering stage,the Pb content was higher in the Pb+Zn stress of Carex putuoshanensis sp.than Pb stress,but this phenomenon was contrary in Carex evergold,so it’s indicated that appropriate concentration of Zn might enhance the absorption of Pb in Carex putuoshanensis sp.(2)Pb,Zn,Pb+Zn stress promoted the synthesis of GSH contents of Carex putuoshanensis sp.and Carex evergold at different growth stages.In the flowering stage,the GSH content of two species of Carex reached the maximum,so the flowering stage was the key period for the synthesis of GSH.In different treatments during the flowering stage,under Pb+Zn stress,the GSH content in shoots and roots of Carex putuoshanensis sp.were increased by 33.45%,24.80%,76.81%,9.78% in comparison to single Pb and Zn treatment which indicated that Pb+Zn showed synergistic effect on the synthesis of GSH in Carex putuoshanensis sp.However,the GSH of Carex evergold in shoots and roots were decreased by 40.07%、18.37% and 14.79% in comparison to single Pb and Zn treatment which indicated that Pb+Zn showed an inhibitory effect on the synthesis of GSH in Carex evergold.(3)The analysis of GCS gene and encoded protein structure of GSH synthetase of Carex putuoshanensis sp.and Carex evergold showed that the GCS gene(CpGCS)and the GCS gene(CeGCS)of Carex pilosa had 1314 bp and 1392 bp bases,encoding 437 and 463 amino acids,their molecular weight were 50.99 and 53.11 KDa and isoelectric points were 5.07 and 5.05,respectively.Both of them were hydrophilic proteins.The protein encoded by the CpGCS and CeGCS genes in the subcellular location were mainly located in the nucleus and mitochondria.The amino acid sequences of the CpGCS gene and the Ce GCS gene were similar to those of Zinnia,rice,and corn,being 88%,83%,87%,85%,88%,and 90%,respectively.The amino acid sequence of the gene included the domain of the glutamic cysteine ligase and γ-glutamyl cysteine synthetase,which were the key of two Carex species in response to Pb and Zn stress.Through the GCS expression analysis of two species of Carex at different growth stages with Pb,Zn and Pb+Zn stress,it was found that the expression of GCS in shoots and roots of two Carex species was strengthen,the maximum was showed in flowering stage,and the GCS gene expression was similar to the changes of GSH content in two species of Carex.The expression of CpGCS in shoots and roots was the highest under Pb+Zn stress of 12.53 times and 8.83 times that of the control during flowering stage.Meanwhile,the expression of CpGCS is greater than the expression of CeGCS.This indicated that the binding amount of GSH catalyzed by the CpGCS protein and Pb was higher than that of catalyzed by the CeGCS protein which was also a characteristic of Carex.(4)The absorption and translocation of Pb and the expression of GSH in Carex putuoshanensis sp.and Carex evergold had a significant positive correlation under the Pb,Zn and Pb+Zn stress.