霸王环核苷酸门控通道基因ZxCNGC5的克隆及表达模式分析

Cloning and expression analysis of cyclic nucleotide-gated channels gene ZxCNGC5 from Zygophyllum xanthoxylum

钙离子(Ca^(2+))作为生命活动过程中重要的第二信使,对植物的生长发育至关重要。环核苷酸门控离子通道(cyclic nucleotide-gated channels,CNGCs)是一类Ca^(2+)通道,在植物的花粉发育、免疫反应以及响应逆境胁迫等生理过程中发挥着重要作用。本研究通过RACE和RT-PCR技术克隆了荒漠旱生植物霸王(Zygophyllum xanthoxylum)CNGCs家族的一个编码基因,命名为ZxCNGC5。生物信息学分析显示其编码728个氨基酸,包含CNGCs家族所特有的6个跨膜域、1个P环以及环核苷酸结合域(cyclic nucleotide-binding domain,CNBD)和钙调蛋白结合域(calmodulin-binding domain,CaMBD);系统进化树将CNGCs家族分为5个亚族(Ⅰ、Ⅱ、Ⅲ、ⅣA和ⅣB),Zx CNGC5属于第Ⅱ亚族;组织特异性分析显示该基因主要在根中表达;在0.01和10 mmol·L^(-1) CaCl_2处理下,ZxCNGC5在根中的表达量短期内均显著升高,并分别在3和12 h达到最高,随后逐渐降低,表明ZxCNGC5在根中的表达受外界CaCl_2的短期诱导。

Ca^（2＋）, a critical second messenger in the processes of plant life, is essential for the growth and development of plants. Cyclic nucleotide-gated channels（CNGCs） are Ca^（2＋）-permeable channels that play an important role in pollen tube guidance, responses to biotic and abiotic stresses as well as immune responses. Here, by RACE and RT-PCR technology, we cloned a new CNGC from Zygophyllum xanthoxylum, designated as ZxCNGC5. By bioinformatics analysis of the ZxCNGC5, we found that this gene encoded 728 amino acids, including six transmembrane helix with a Pore loop, cyclic nucleotide-binding domain and calmodulin-binding domain, which were unique to CNGCs family. Phylogenetic analysis showed that CNGCs family could be divided into 5 subfamily（Ⅰ、Ⅱ、Ⅲ、ⅣA and ⅣB） and ZxCNCG5 belonged to the Ⅱ subfamily. Tissue specificity analysis suggested that the gene was especially expressed in roots. Further, under the 0.01 and 10 mmol·L^（-1） CaCl_2 treatment, the expression of ZxCNGC5 in roots was significantly induced in short term and reached the highest at 3 and 12 h, and then decreased gradually. These results indicated that the expression of ZxCNGC5 in roots was induced in short time when adding the CaCl_2.