玉米SRO基因家族的鉴定及表达分析

【目的】SRO(similar to rcd one)是植物所特有的一类小蛋白家族,其在植物的生长发育,及应对非生物胁迫中发挥着重要功能。基于玉米全基因组数据库,鉴定玉米SRO家族基因,分析其序列、基因定位、蛋白结构及其系统进化关系,同时解析Zm SROs在玉米组织表达特异性及其在高盐和干旱胁迫下的表达变化,为阐明SRO基因在玉米生长和逆境响应中的功能研究奠定基础。【方法】利用拟南芥SRO家族基因为探针,在玉米全基因组查找并下载玉米SRO基因序列,并从Maize GDB中获取玉米SRO基因相关信息,包括CDS、氨基酸序列及染色体位置等。通过生物信息学工具(GSDS2.0、Expasy-protparam、SOPMA、Plant-m PLoc、EMBL-EBI、MEME)对获得序列的基因结构、蛋白质分子量、等电点、二级结构、亚细胞定位、保守结构域、保守基序原件等进行预测和分析。同时利用Clustalx(1.83)和MEGA 6.0软件进行同源序列比对并构建系统进化树。运用实时荧光定量PCR技术分析玉米SRO组织表达特异性及其在高盐和干旱胁迫下SRO的表达变化情况。【结果】从玉米全基因组共鉴定6个SRO家族基因,分别命名为Zm SRO1a—Zm SRO1f。Zm SROs分布于第1、4、5和9染色体,包含2—5个内含子。序列分析发现CDS序列长度在1 215—1 791 bp;编码氨基酸数目为404—596 aa;分子量为45.23—66.78 k D;等电点为7.01—9.17。亚细胞定位分析发现Zm SRO1a/Zm SRO1b/Zm SRO1c/Zm SRO1d定位于叶绿体,Zm SRO1e则定位于过氧化氢酶体,Zm SRO1f定位于细胞核。系统进化树分析发现Zm SROs分为3个亚类,Ⅰa亚类包括Zm SRO1a/Zm SRO1b/Zm SRO1c,Ⅰb亚类包括Zm SRO1f,Ⅰc亚类包括Zm SRO1d/Zm SRO1e。保守结构域分析结果显示Zm SRO1a/Zm SRO1b/Zm SRO1c/Zm SRO1d/Zm SRO1e包含PARP和RST结构域,缺少WWE结构域,Zm SRO1f包含WWE和PARP催化中心,RST结构域缺失。Zm SROs蛋白共找到5个保守基序,命名为基序1—5。Zm SRO1a/Zm SRO1b/Zm SRO1c包含所有保守基序,Zm SRO1d/Zm SRO1e缺少保守基序3,Zm SRO1f缺少保守基序5。组织表达分析发现Zm SROs在根系特异性表达。高盐胁迫下,玉米根系中Zm SRO1a/Zm SRO1b/Zm SRO1c/Zm SRO1d/Zm SRO1e在1 h时显著上调表达,地上部中Zm SRO1a/Zm SRO1b/Zm SRO1d/Zm SRO1e均下调表达,而Zm SRO1f在处理6 h显著上调表达。干旱胁迫下,玉米根系Zm SRO1e在1 h显著上调表达,Zm SRO1f在24 h显著上调表达;地上部中Zm SRO1a/Zm SRO1b/Zm SRO1d/Zm SRO1e均下调表达。【结论】玉米SRO家族基因包含6个成员,被划分为3个亚类,6个Zm SROs在玉米根系中特异性表达,且可以不同程度地响应干旱和高盐胁迫。

Genome-Wide Identification and Expression Analysis of SRO Genes Family in Maize

【Objective】The SRO (similar to rcd one) is a group of plant-specific proteins which have important functions in plant growth and development, and response to abiotic stress. Based on maize genome information, the SRO family genes were identified, and the sequences, gene localization, protein structure and their evolutionary relationships were analyzed. Meanwhile, the SRO family genes tissue-specific expression profiles and expression pattern under salt and drought stresses of ZmSROs were analyzed. This research can lay a foundation for researching the function of SRO family genes in the growth and response mechanisms of stress in maize. 【Method】The Arabidopsis SRO protein sequences were used as queries to identify SRO in maize genome and download all the SRO gene sequences, which information regarding the maize SRO genes, including CDS sequences , amino acid sequences and chromosome location were obtained from MaizeGDB. The gene structure, protein molecular weight, isoelectric point, secondary structure, subcellular localization, conserved domain, and conserved element were also prospected and analyzed by GSDS2.0, Expasy-protparam, SOPMA, Plant-mPLoc, EMBL-EBI, MEME bioinformatics tools. Meanwhile the homologous sequence alignment and phylogeny were analyzed by Clustalx (1.83) and MEGA6.0 software. The expression levels of ZmSROs genes in different maize tissues and under high salt and drought stresses were analyzed by real-time fluorescence quantitative PCR. 【Result】Six SRO family genes were identified from Maize genome, and designated ZmSRO1a to ZmSRO1f. ZmSROs were mapped on 1, 4, 5 and 9 chromosome, and contained two to five introns. The CDS of 6 ZmSROs varied in length from 1,215 to 1,791 bp, and their predicted protein products ranged from 404 to 596 aa, with corresponding molecular masses of 45.23 kD and 66.78 kD, and with predicted isoelectric points in the range of 7.01 to 9.17. Subcellular localization analysis showed that ZmSRO1a/ZmSRO1b/ZmSRO1c/ZmSRO1d were located in the chloroplast, ZmSRO1e was located in the peroxisome, and ZmSRO1f was located in the nucleus. Phylogentic analysis revealed that ZmSROs can be divided into three subgroups. Subgroup Ⅰ a contains ZmSRO1a/b/c, subgroups Ⅰ b contains ZmSRO1f, and subgroup Ⅰ c contains ZmSRO1d and ZmSRO1e. Conservative structure domain analysis showed that ZmSRO1a/ ZmSRO1b/ ZmSRO1c/ ZmSRO1d/ ZmSRO1e contain the PARP and RST domain, lack the WWE domain. ZmSRO1f contains the PARP and WWE domain, lacks the RST domains. A total 5 motif were identified from ZmSROs proteins，named motif 1—motif 5. ZmSRO1a/ZmSRO1b/ZmSRO1c contain all of motif, ZmSRO1d/ ZmSRO1e lack the motif 3，ZmSRO1f lacks the motif 5. Different tissues expression assay showed that all ZmSROs had specific expressions in root. The expression of ZmSRO1a/ZmSRO1b/ZmSRO1c/ZmSRO1d/ZmSRO1e in root were significantly up-regulated under high salinity treatment for 1 h. ZmSRO1a/ZmSRO1b/ZmSRO1c/ZmSRO1d/ZmSRO1e were down-regulated in shoots, However, the expression of ZmSRO1f in shoot was significantly up-regulated under high salinity treatment for 6 h. ZmSRO1e in root was up-regulated under drought stress for 1 h and that of ZmSRO1f was up-regulated for 24 h. Meanwhile, the expressions of ZmSRO1a/ ZmSRO1b/ZmSRO1d/ZmSRO1e in shoot were down-regulated under drought stress and that of ZmSRO1c and ZmSRO1f had no significant changes in shoot. 【Conclusion】Maize SRO family contains six genes, and ZmSROs genes could be classified into threes subgroups. Six of ZmSROs genes had specific expressions in root and could respond to high salt and drought stresses in varying degrees.