烟草NtCCX2基因的克隆与表达分析

Cloning and Expression Analysis of NtCCX2 Gene in Tobacco

以野生型K326土培烟草为试验材料,对NtCCX2基因进行克隆与表达模式分析,明确其在烟草响应镉等胁迫应答中的作用。结果表明,NtCCX2基因全长2464 bp,CDS区1926 bp,编码641个氨基酸,具有CCX家族显著的特征,在跨膜区有2个α-重复区域:α1模式基序GNGAPD和α2模式基序G(N/D)SxGD。NtCCX2基因具有明显的时空表达特性,在幼苗期和旺长期叶中的相对表达量最高,在成熟期根和花中的相对表达量较高。NtCCX2基因启动子含有脱落酸(ABA)等激素信号以及抗逆相关的响应元件,在根和叶中的表达除了受干旱、盐和镉胁迫诱导外,还对ABA、茉莉酸甲酯(MeJA)和乙烯利产生不同的响应。其中,ABA处理2 h后,NtCCX2基因在根中相对表达量是0 h的3.7倍;MeJA处理8 h后,叶中NtCCX2基因相对表达量是0 h的2.1倍;乙烯利处理2 h后,NtCCX2基因在根和叶中相对表达量均增加。降镉灵等降镉药剂能够下调该基因的表达。

To investigate the role of NtCCX2 gene in tobacco in response to cadmium and other stresses,it was cloned from tobacco and its expression pattern was analyzed.The results showed that the total length of NtCCX2 gene was 2464 bp,and the CDS region was 1926 bp,encoding 641 amino acids.It had significant characteristics of CCX family,and there were twoα-repeat regions in the transmembrane region:α1 pattern motif GNGAPD andα2 pattern motif G(N/D)SxGD.NtCCX2 gene had obvious spatial and temporal expression characteristics.Its expression was the highest in leaves at seedling stage and flourishing stage,while was higher in roots and flowers at mature stage.The promoter of NtCCX2 gene contained ABA and other hormone signals as well as stress-related response elements.In addition to drought,salt and cadmium stresses,the expression of NtCCX2 gene in roots and leaves also had different responses to ABA,MeJA and ethylene.Among them,after 2 hours of ABA treatment,the relative expression level of NtCCX2 gene in the root was 3.7 times that of 0 hour;After 8 hours of MeJA treatment,the relative expression level of NtCCX2 gene in the leaves was 2.1 times that of 0 hour;After2 hours of ethephon treatment,the relative expression level of NtCCX2 gene in both the root and leaves increased.Cadmium-reducing agents could down-regulate the expression of this gene.