毛白杨植物络合素合酶(PtPCS)基因克隆及其表达研究  

Cloning and Expression Analysis of a Phytochelatin Synthase Gene(PtPCS) in Populus tomentosa Carr.

作　　者：柳玉霞[1] 王晓桐[1] 苏旭东[1] 代亮[1] 张志毅[1] 徐吉臣[1] 

机构地区：[1]北京林业大学林木育种国家工程实验室,北京100083

出　　处：《分子植物育种》2012年第2期174-183,共10页Molecular Plant Breeding

基　　金：林业公益性行业科研专项(201004009);北京市自然科学基金项目(5122019);北京林业大学本科生科研训练项目共同资助

摘　　要：植物络合素(PCs)是植物细胞中一类螯合重金属离子的多肽,对细胞解毒和重金属的富集有重要的作用。植物络合素合酶(PCS)是合成PCs途径中的关键酶。本研究克隆了毛白杨的植物络合素合酶基因PtPCS,该基因cDNA序列全长1512bp,可编码503个氨基酸;与其它8种植物同源基因比对显示,它们的氨基酸序列相似性在67%～74.1%之间;构建进化树发现,这9种植物明显的分为两大分支,并且两大分支PCS蛋白的高级结构显示出明显的差异,一种呈月牙状,一种为伞状,重金属超富集植物均为月牙状结构。对毛白杨在不同镉浓度处理下PtPCS基因的表达情况分析发现,毛白杨根、茎、叶中PtPCS基因均表现出先升高后缓慢降低的表达趋势,并且在同一镉浓度处理下,毛白杨不同器官PtPCS基因的表达具有规律性,即根表达量最强,茎次之,叶片最弱。研究结果不仅为植物育种提供了重要的基因资源,也为剖析毛白杨的镉抗性和富集特性的研究奠定了良好的基础。Phytochelatins （PCs）, a class of heavy metalchelating peptides from plants, play an important role in detoxifying and accumulating of heavy metals in plant cells. In this research, the phytochelatin synthase （PCsynthases, PCS） gene PtPCS in Populus tornentosa Carr. was cloned. The full length of cDNA is 1512 bps, and it encodes 503 amino acids. The amino acid sequence alignment of PtPCS and homologous genes of other 8 speciesshowed the homology ranged from 67% to 74.1%. The phylogenetic tree based on PCS proteins in 9 species divides into two branches, and the PCS＇s tertiary structures of them have significant differences. One is crescent, while theother is umbrella. Moreover, all PCS structures in the heavy-metal-hyperaccumulator plants are all crescent. Gene expression analysis showed, the PtPCS gene expression in roots, stems, and leaves of poplar seedlings which hadbeen treated with different concentrations of Cd^2＋ （0-300 mg/L）, increased first and then decreased slowly. It also showed in the same treatment of Cd^2＋ the expression in different organs was regular. The expression in root was thestrongest, then in stem, the least was in leave. The characterized PtPCS gene in this research could be an important genetic resource for plant breeding, and also could be a basis for exploring the mechanism of the resistance and accumulation of Cd^2＋ in Populus tomentosa Carr.

关 键 词：毛白杨 植物络合素合酶(PCS) 基因克隆 基因结构 基因表达 

分 类 号：S792.117[农业科学—林木遗传育种]