胡杨Na^+/H^+反向运输载体(PeNHX2)基因的克隆与序列分析

Cloning and Sequence Analysis of Na^+/H^+ Antiporter(PeNHX2) from Populus euphratica

植物液泡膜上Na+/H+反向运输载体(Na+/H+antiporterNHX)已被证明在盐胁迫中发挥关键作用,该研究旨在从胡杨中克隆获得耐盐相关的的完整cDNA序列,为进一步比较胡杨的耐盐基因的差异,探讨胡杨的耐盐分子机理奠定了基础,并为通过转基因手段提高木本植物的耐盐能力提供侯选基因。根据已发表NHX的同源基因序列,采用特异性引物扩增核心片段,并结合5’与3’RACE技术,成功地从胡杨(populus euphratica)克隆获得PeNHX2,其cDNA全长1638bp。测序和序列分析结果表明该基因与已发表毛白杨(Populus tomentosa)PtNHX基因在核酸水平及蛋白质水平上同源性均达到最高,依次为90.6%和88.25%。利用DNAMAN软件进一步分析得知,该基因与新疆盐生植物中所克隆获得的的犁苞滨藜(Atriplex dimorphostegia)AdNHX1、灰绿藜(Chenopodium glaucum)CgNHX1、盐爪爪(Kalidium foliatum)KfNHX同源性也较高,核酸水平上依次为75.1%、74.8%、74.3%,蛋白质水平依次为78.3%、79.0%、78.3%。PeNHX2与NCBI已注册的部分PeNHX1序列,在核酸或蛋白质水平同源性(72.34%和73.72%)均较低,分析它们可能同属于胡杨NHX基因家族,相关生物学功能有待于进一步研究。

The Na^＋/H^＋ antiporter has been proved to play an important role in salt tolerance of plant. To further elucidate the mechanism of salt - tolerance of P. euphratica and provide the candidate gene to improve the salt tolerance of wood plants through transgenic technology in the future, A Na^＋/H^＋ Antiporter（ named PeNHX2）were to be cloned. According to the published sequence of NHX, conservative sequence primers were designed, and combined with the technology of RACE, the full length cDNA sequence of PeNHX2 was gotten. The results of blasting this gene on NCBI showed that PeNHX2 had the highest homology with Populus tomentosa NttX （PtNHX）. While the homology of PeNttX with other NHX genes of halophyfic plants in Xinjiang： Atriplex dimorphostegia NHX （AdNHX1）, Chenopodium glaucum NHX （ CgNHX1 ）, Kalidium foliatum NHX （KfNHX） on nucleotide level PeNHX2 were respectively 75.1%, 74.8 %, 74.3 % identity, and on protein level, the corresponding homologies were 78.3% ,79.0% ,78.3%. But PeNHX2 had relatively low identities with PeNHX1 published on NCBI, it may show that the two genes belong to the same gene family , but their functions in salt tolerance need to be further characterized.