盐穗木HcPEAMT基因的克隆及表达分析

Cloning and Expression Analysis of HcPEAMT Gene from Halostachys caspica

依据盐穗木编码PEAMT的EST序列设计引物,通过快速扩增cDNA末端技术,获得盐穗木磷酸乙醇胺甲基转移酶(phosphoethanolamine N-methyltransferase,PEAMT)全长cDNA,命名为HcPEAMT。序列分析表明HcPEAMT基因开放阅读框为1 482bp,编码494个氨基酸,推测分子量为56.3kD,理论等电点为5.51。保守结构域分析表明,HcPEAMT含有2个独立的S-腺苷甲硫氨酸依赖性甲基转移酶的保守结构域,每个结构域含有4个基序。系统进化树分析确认HcPEAMT与盐生植物盐角草的亲缘关系较近。实时荧光定量PCR分析表明,盐胁迫3h时,盐穗木同化枝和根中HcPEAMT基因的表达迅速上调并达到最大值,分别为对照的4.3倍和6.7倍。脱落酸(ABA)胁迫3h时,同化枝中HcPEAMT的表达量达到最高,而根中HcPEAMT的表达在12h才达到最高,表达量分别为对照的2.6和2.5倍。研究结果表明,HcPEAMT基因表达受盐胁迫的强烈诱导,也受ABA胁迫的诱导。该研究结果有助于阐明HcPEAMT基因表达与植物抗逆性的相关性。

Primers for phosphoethanolamine N-methyltransferase（PEAMT）gene from the halophyte Halostachys caspica were designed according to the EST sequence,and the full length cDNA of PEAMTgene was cloned by using RACE（rapid amplification of cDNA ends）.The obtained cDNA was named as HcPEAMT.Sequence analysis indicated that HcPEAMTcontains an open reading frame（ORF）of 1 482 bp,which encodes 494 amino acids with a molecular weight of 56.3kD and a theoretical pI of 5.51.Conserved domain analysis showed that HcPEAMT has two separate conserved domains of S-adenosylmethionine-dependent methyltransferase,and each domain contains four motifs.Phylogenetic tree analysis indicated that HcPEAMT was closer to the halophyte of Salicornia europaea.Real time quantitative PCR results showed that the expression of HcPEAMTgene in assimilating branches and roots after salt stress for 3h was rapidly up-regulated and reached the highest,which was 4.3-fold and 6.7-fold of that of the respective controls.When stressed by abscisic acid（ABA）,the expression of HcPEAMTgene in assimilating branches and root reached the highest level at 3and 12 h,and about 2.6-fold and 2.5-fold of the controls,respectively.These results indicated that the expression of HcPEAMTgene was strongly induced by salt stress,and also by ABA stress.Our results would help to clarify the relationship between HcPEAMTexpression andplant resistance.