玉米NAC转录因子基因ZmNAM的克隆及表达分析

Cloning and Expression Analysis of Transcription Factor Gene ZmNAM in Maize(Zea mays L.)

为探究候选基因ZmNAM的功能,本研究从甜玉米自交系1132及其变异系704中克隆得到该基因。生物信息学分析表明,ZmNAM的c DNA长度为1 548 bp,开放阅读框(ORF)为1 302 bp,编码一个由433个氨基酸残基组成的蛋白,蛋白具有亲水性,N-末端具有保守的NAC结构域,定位于细胞核中,具有9个糖基化位点和35个磷酸化位点;与自交系1132相比,变异系在非编码区与编码区中的C-末端转录激活功能域对应核苷酸序列中存在差异,可导致多个氨基酸发生变异。系统进化分析结果表明,玉米ZmNAM蛋白属于NAC转录因子家族中的VND亚族,与拟南芥中的At VND3亲缘关系最近;时空特异性表达分析表明,不同发育时期内ZmNAM在根中的表达量明显高于其他器官,说明ZmNAM基因可能在调控玉米根部的生长发育过程中发挥着重要作用。变异系704中ZmNAM在各个发育时期和发育器官中表达水平基本都明显高于自交系1132,其中在根中的表达水平差异最明显。本研究结果为深入研究ZmNAM基因在玉米生长发育过程中的作用提供了理论支持。

ZmNAM is a candidate gene identified in the previous study. To investigate its function in maize,ZmNAM was isolated from the sweet corn line ＂1132＂and its variant line ＂704＂. Bioinformatics analysis showed that the c DNA of ZmNAM was 1548 bp and contained a 1302 bp open reading frame（ ORF） encoding a hydrophilic protein with 433 amino acid residues. The ZmNAM protein had a conserved NAC domain in its N-terminal and was also predicted to locate in nucleus and contain nine glycosylation sites as well as 35 phosphorylation sites. Compared with inbreed line1132,there were differences in nucleotide sequence of non-coding regions and the transcriptional actiration domain of Cterminal in coding region in variant line,which may lead to variation of multiple amino acids. Phylogenetic analysis revealed that ZmNAM was a member of NAC transcription factor family belonging to VND subgroup and had a closest genetic relationship with At VND3 in Arabidopsis. The real-time PCR showed that expression level of ZmNAM in root was higher than that in other organs of maize in different development stages. It suggests that ZmNAM may play an important role in regulating the growth and development of root in maize. Furthermore,the expression level of ZmNAM in variation line 704 was higher than that in inbred line 1132 in most development stages and development organs,especially in root.These results provide a scientific evidence for further elucidating the role of ZmNAM during development of maize.