中文摘要：

利用生物信息学分析方法挖掘玉米（Zea mays）不同组织间差异表达的基因,揭示玉米生长发育过程的分子机理,本研究从NCBI数据库中下载获得玉米自交系Mo17和B73根和芽的转录组数据,发现了5个在根中高表达的氧甲基转移酶（O-methyltransferase,OMT）基因,在B73全基因组中鉴定到另外的23个拷贝。对玉米的28个氧甲基转移酶基因的结构、保守模体以及进化分析表明,其不同于咖啡酸氧甲基转移酶（caffeic acid O-methyltransferase,COMT）基因和咖啡酰辅酶A氧甲基转移酶（caffeoyl coenzyme A 3-O-methyltransferase,CCo AOMT）基因,是一类新型的氧甲基转移酶基因家族。这类基因家族含有5个进化分支,其中有两个进化分支分别包含苯并噁嗪类基因7（benzoxazinless 7,Bx7）和Bx10,参与苯并噁嗪类物质的生物合成,表明该类基因在玉米的抗病虫反应中发挥着重要作用。染色体结构与进化分析表明,这类新型氧甲基转移酶基因家族的扩增大多是通过串联重复和片段复制来实现的。对这些基因在玉米的巢式关联定位（nested association mapping,NAM）群体亲本中的表达模式分析表明,其表达模式十分复杂。该研究结果为进一步了解COMT基因的生物学功能及其利用提供了理论依据和参考,并对研究该基因家族的催化机制及其表达调控模式具有重要的指导意义。

英文摘要：

With the development of high-throughput sequencing technique, the whole genome sequencing and transcriptome sequencing in maize（Zea mays） have been completed. The differentially expressed genes can be discovered by bioinformatic methods in different maize tissues, which will further reveal the molecular mechanism of the growth and development process. In this study, the transcriptome datasets of maize inbred lines Mo17 and B73, from the NCBI GEO database, were downloaded, and 5 genes（GRMZM2G311036,GRMZM2G336824, GRMZM2G059465, GRMZM2G124799, GRMZM2G147491）, belonging to O-methyltransferase（OMT） gene family, which were expressed higher in roots than in shoots in both maize inbreds B73 and Mo17, were found, and additional 23 copies were identified from the maize B73 reference genome. The plant O-methyltransferases（OMTs） are dependent on S-Adenosyl-L-methionine（SAM）, which can catalyze a vari-ety of secondary metabolites such as flavonoids, alkaloids and phytoalexins that play an important role in various stages of plant growth and development, the resistance of the invasion of exotic pathogens. All 28 OMT genes were located on 8 chromosomes. Most of them contained 2 exons and one intron（except for GRMZM2G349791 and GRMZM2G104730, which contained one exon and 8 exons, respectively） with the length varied from 291 to 921 bp. The genes structures, conserved motifs and evolutionary analysis revealed that all the 27 OMTs belonged to a new type of OMT gene family that was different from the caffeic acid Omethyltransferase（COMT） and caffeoyl coenzyme A 3- O- methyltransferase（CCo AOMT）. The new type of OMT genes contained more than 8 conservative motifs except GRMZM2G147503. They were the same protein family（O-methyltransferase COMT-type family） as COMT based on the prediction of protein family. Furthermore, the motifs 2, 4 and 9 were only presented in the new OMT gene family, while the motifs 5, 6 and 7 were shared by the new OMT and COMT, and the CCo AOMT（GRMZM2G127948） had no com