玉米咖啡酸O-甲基转移酶的全基因组鉴定与功能分析

Identification and Functions of Caffeic Acid O-methyltransferase Genes in Maize

【目的】咖啡酸O-甲基转移酶(Caffeic acid O-methyltransferase,COMT)是褪黑素生物合成中的关键酶,在植物的生长、发育和抵御胁迫中发挥着重要的作用。本研究旨在探究COMT在玉米全基因组中的分布与盐胁迫响应情况,鉴定玉米咖啡酸O-甲基转移酶(COMT)基因。【方法】通过分析玉米COMT基因家族成员的结构特征、系统发育关系、基因结构、表达模式等,对ZmCOMTs基因进行系统分析,并通过过表达ZmCOMT12拟南芥对ZmCOMT的功能进行初步验证。【结果】在玉米全基因组中共鉴定出了28个COMT基因,根据系统发育分析分为2个分支(分支Ⅰ~Ⅱ),大部分的COMT成员具有相似的motif组成和基因结构特征。利用玉米数据库分析ZmCOMTs的表达模式发现部分基因存在组织特异性,实时荧光定量PCR发现ZmCOMTs被盐胁迫诱导表达,说明ZmCOMTs成员参与了盐胁迫的调控,过表达ZmCOMT12拟南芥提高了褪黑素的含量和耐盐性。【结论】通过序列比对、亲缘关系、蛋白结构分析得到了假定的褪黑素合成基因ZmCOMT12,过表达拟南芥发现该基因与褪黑素的合成和耐盐性相关。

【Objective】Localization in genome and response to salt stress of the genes of caffeic acid O-methyltransferase(COMT),a key melatonin biosynthesis enzyme relating to plant growth,development,and stress resistance,in maize were studied.【Method】Structure,phylogenetics,and expressions of the COMT family in maize(ZmCOMT)were analyzed.Functions of the genes were verified by overexpressing ZmCOMT12 in Arabidopsis thaliana.【Result】Twenty-eight COMTs were identified in the maize genome and phylogenetically divided into BranchⅠand Branch II.Most of them were structurally similar with a like motif composition,and some had tissue specific expressions.As revealed by RT-PCR,ZmCOMTs could be induced by salt stress,indicating its association with the stress regulation.The overexpressed ZmCOMT12 significantly elevated the melatonin content and salt tolerance of Arabidopsis.【Conclusion】ZmCOMT12 was hypothesized as the melatonin synthesizing gene by the sequence alignment,genetic relationship,and protein structure analyses.