大白菜NHX基因家族的鉴定与表达分析

Identification and expression analysis of NHX gene family in Chinese cabbage

摘要:

Na⁺/H⁺逆向转运蛋白（Na⁺/H⁺ antiporter， NHX）基因家族在植物响应盐胁迫中发挥重要作用。本研究鉴定了大白菜NHX基因家族成员，并分析了大白菜NHX基因（Brassica rapa ssp. Pekinensis NHX，BrNHXs）响应高温、低温、干旱和盐胁迫等非生物逆境的表达模式。结果表明，在大白菜中共鉴定到9个NHX基因家族成员，分布在大白菜的6条染色体上，其氨基酸数目在513–1 154 aa之间，相对分子量集中在56 804.22–127 856.66 kDa，等电点位于5.35–7.68之间。该基因家族成员主要存在于液泡中，基因结构完整，外显子的数目介于11–22之间。大白菜NHX基因家族编码的蛋白质二级结构都具有α-螺旋、b-转角和不规则卷曲结构，其中α-螺旋发生频率较高。实时荧光定量PCR （quantitative real-time PCR，qRT-PCR）分析显示，该基因家族成员在高温、低温、干旱和盐胁迫下均有不同程度地响应，且在不同时间表达差异显著。以BrNHX02和BrNHX09对这4种胁迫的响应最为显著，表达量在处理72 h时均显著上调，可作为候选基因进一步验证其功能。

Abstract:

Na⁺/H⁺ antiporter (NHX) gene subfamily plays an important role in plant response to salt stress. In this study, we identified the NHX gene family members of Chinese cabbage and analyzed the expression patterns of BrNHXs gene in response to abiotic stresses such as high temperature, low temperature, drought and salt stress. The results showed that there were 9 members of the NHX gene family in Chinese cabbage, which were distributed on 6 chromosomes respectively. The number of amino acids was 513-1 154 aa, the relative molecular weight was 56 804.22-127 856.66 kDa, the isoelectric point was 5.35-7.68. Members of BrNHX gene family mainly existed in vacuoles, the gene structure is complete, and the number of exons is 11-22. The secondary structures of the proteins encoded by the NHX gene family in Chinese cabbage had alpha helix, beta turn and random coil, and the alpha helix occurred more frequently. Quantitative real-time PCR (qRT-PCR) analysis showed that the gene family members had different responses to high temperature, low temperature, drought and salt stress, and their expression levels differed significantly in different time periods. BrNHX02 and BrNHX09 had the most significant responses to these four stresses, and their expression levels were significantly up-regulated at 72 h after treatments, which could be used as candidate genes to further verify their functions.