玉米泛素结合酶基因家族分析及低氮胁迫下亚家族UBC2的表达分析

泛素结合酶是泛素/蛋白酶体途径的重要组成部分,在蛋白质的泛素化过程中具有重要作用。本研究利用生物信息学对玉米泛素E2家族成员进行系统进化及基因结构分析。系统进化分析显示,玉米泛素结合酶基因可分为6个亚家族,各亚家族成员数目差异较大。基因数目最多的亚家族是UBC1,为22个。成员数最少的是UBC3,仅为5个。以亚家族UBC2为研究对象,发现UBC2中一共存在4对旁系同源基因,分别是ZmUBC3/ZmUBC70、ZmUBC8/ZmUBC34、ZmUBC31/ZmUBC53以及ZmUBC45/ZmUBC66。对UBC2中成员进行基因结构分析发现,互为旁系同源的基因其基因结构相似。ZmUBC45/ ZmUBC66含有外显子数量最多,为9个,而ZmUBC31/ZmUBC53外显子含量最小,仅为4个。基因基序分析结果显示,ZmUBC3/ZmUBC70含有基序数量最多（8个）,ZmUBC8/ZmUBC34与ZmUBC31/ZmUBC53基序含量最小（均为3个）。基因启动子作用元件分析显示,泛素E2基因启动子元件类型可分为光响应、激素响应和胁迫响应元件、组织表达相关元件以及周期性调控相关元件5大类。基因不同组织表达分析显示,被检测基因在玉米雌花中均有很高的表达量,在根和茎中表达量最低。低氮胁迫结果显示,所有被检测基因在低浓度NO₃ ^-处理下,其基因相对表达量在1 h降至最低,随后逐渐上升。在低浓度NH₄ ⁺处理条件下,各基因表达量逐渐降低,在24 h达到最低值。以上结果表明,泛素结合酶亚家族UBC2基因受低氮胁迫的影响其表达量发生了变化。

Bioinformatics Analysis of Ubiquitin-conjugating Enzymes and Expression Analysis of UBC2 Gene Sub-family in Response to LowNitrogen Stress in Maize

Ubiquitin-binding enzyme is an important component of the ubiquitin/proteasome pathway, playing an important role in protein ubiquitination. In this study, bioinformatics tools were used to systematically analyze the maize gene structure and evolution relationship of ubiquitin E2 family members. Phylogenetic analysis showed that the maize ubiquitin-binding enzyme genes could be divided into six subfamilies. The number of the members in each subfamily is different. Subfamily UBC1 contained the largest numbers (22 genes), while the least number of members was UBC3, only five genes. Based on the subfamily UBC2, it was found that there were four paralogous genes in UBC2, namely ZmUBC3/ZmUBC70, ZmUBC8/ZmUBC34, ZmUBC31/ZmUBC53 and ZmUBC45/ZmUBC66. Gene structure analysis revealed that the paralogous genes were similar in structure. ZmUBC45/ZmUBC66 contained the largest number of exons (9 exons) while ZmUBC31/ZmUBC53 only had four. Gene motif analysis results showed ZmUBC3/ZmUBC70 contained eight motifs while ZmUBC8/ZmUBC34 and ZmUBC31/ZmUBC53 only had three. Gene promoter element analysis revealed that there were five component types, which were photo response elements, hormone response elements, stress response elements, tissue expression related components, and periodic regulation related components. Gene expression analysis indicated that all the tested genes had high expression levels in the female flowers but the lowest expression in roots and stems. The low nitrogen stress test suggested that the relative expression of all the tested genes decreased rapidly to a minimum at 1th hour, then increased slowly. Under low concentration of NH₄ ⁺ treatment, the expression level of each gene gradually decreased and reached the lowest value at the 24th hour point. The results suggested that the maize ubiquitin-binding enzyme genes may be involved in the response of low nitrogen stress pathway.