Homologous cloning, characterization and expression of a new halophyte phytochelatin synthase gene in Suaeda salsa  

作　　者：丛明 赵建民 吕家森 任志明 吴惠丰 

机构地区：[1]Key Laboratory of Coastal Zone Environmental Processes,Yantai Institute of Coastal Zone Research(YIC),Chinese Academy of Sciences(CAS),Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes,YICCAS,Yantai 264003,China [2]Biology School of Yantai University,Yantai 264005,China

出　　处：《Chinese Journal of Oceanology and Limnology》2016年第5期1034-1043,共10页中国海洋湖沼学报（英文版）

基　　金：Supported by the 100 Talents Program of the Chinese Academy of Sciences;the Key Technology R&D Program of Shandong Province(No.2012GGA06032)

摘　　要：The halophyte Suaeda salsa can grow in heavy metal-polluted areas along intertidal zones having high salinity.Since phytochelatins can effectively chelate heavy metals,it was hypothesized that S.salsa possessed a phytochelatin synthase(PCS) gene.In the present study,the cDNA of PCS was obtained from S.salsa(designated as SsPCS) using homologous cloning and the rapid amplification of cDNA ends(RACE).A sequence analysis revealed that SsPCS consisted of 1 916 bp nucleotides,encoding a polypeptide of 492 amino acids with one phytochelatin domain and one phytochelatin C domain.A similarity analysis suggested that SsPCS shared up to a 58.6%identity with other PCS proteins and clustered with PCS proteins from eudicots.There was a new kind of metal ion sensor motif in its C-terminal domain.The SsPCS transcript was more highly expressed in elongated and fibered roots and stems(P<0.05) than in leaves.Lead and mercury exposure significantly enhanced the mRNA expression of SsPCS(P<0.05).To the best of our knowledge,SsPCS is the second PCS gene cloned from a halophyte,and it might contain a different metal sensing capability than the first PCS from Thellungiella halophila.This study provided a new view of halophyte PCS genes in heavy metal tolerance.The halophyte Suaeda salsa can grow in heavy metal-polluted areas along intertidal zones having high salinity. Since phytochelatins can effectively chelate heavy metals, it was hypothesized that S. salsa possessed a phytochelatin synthase （PCS） gene. In the present study, the cDNA of PCS was obtained from S. salsa （designated as SsPCS） using homologous cloning and the rapid amplification of cDNA ends （RACE）. A sequence analysis revealed that SsPCS consisted of 1 916 bp nucleotides, encoding a polypeptide of 492 amino acids with one phytochelatin domain and one phytochelatin C domain. A similarity analysis suggested that SsPCS shared up to a 58.6% identity with other PCS proteins and clustered with PCS proteins from eudicots. There was a new kind of metal ion sensor motif in its C-terminal domain. The SsPCS transcript was more highly expressed in elongated and fibered roots and stems （P〈0.05） than in leaves. Lead and mercury exposure significantly enhanced the mRNA expression of SsPCS （P〈0.05）. To the best of our knowledge, SsPCS is the second PCS gene cloned from a halophyte, and it might contain a different metal sensing capability than the first PCS from Thellungiella halophila. This study provided a new view of halophyte PCS genes in heavy metal tolerance.

关 键 词：Suaeda salsa HALOPHYTE phytoehelatin synthase （PCS） homologous cloning heavy metal tissue distribution 

分 类 号：Q943.2[生物学—植物学]