茶树甲基化EGCG生物合成相关OMTs基因的鉴定及表达  

Identification and expression analysis of OMT genes related to O-methylated EGCG biosynthesis in Camellia sinensis

作　　者：罗勇[1] 温贝贝 陈燕 曹桂萍 雷淑敏 李群 王坤波[2,3] LUO Yong;WEN Beibei;CHEN Yan;CAO Guiping;LEI Shumin;LI Qun;WANG Kunbo(School of Chemistry and Environmental Science,Xiangnan University,Chenzhou 423000,China;Key Laboratory of Tea Science of Ministry of Education,Hunan Agricultural University,Changsha 410128,China;National Research Center of Engineering Technology for Utilization of Functional Ingredients from Botanicals,Changsha 410128,China;School of Pharmacy,Xiangnan University,Chenzhou 423000,China)

机构地区：[1]湘南学院化学与环境科学学院,郴州423000 [2]湖南农业大学茶学教育部重点实验室,长沙410128 [3]国家植物功能成分利用工程技术研究中心,长沙410128 [4]湘南学院药学院,郴州423000

出　　处：《应用与环境生物学报》2022年第1期26-33,共8页Chinese Journal of Applied and Environmental Biology

基　　金：湖南省自然科学基金(2020JJ5525);湖南省教育厅科学研究项目(19C1720)资助。

摘　　要：茶树O-甲基转移酶(OMT)可催化甲基化EGCG的生物合成.为进一步获得甲基化EGCG生物合成的关键OMT基因,以不同甲基化EGCG含量的茶树品种金观音(JGY)、金牡丹(JMD)和福鼎大白(FD)为试验材料,基于茶树基因组和转录组数据,通过生物信息学方法,对筛选获得的OMTs基因进行染色体定位、基因结构特征、编码蛋白特性和系统进化关系分析,同时采用实时荧光定量PCR验证茶树OMTs在不同茶树品种的相对表达水平.结果显示,共鉴定出5个在金观音与福鼎大白以及金牡丹与福鼎大白比较组合中显著上调表达的OMT基因,其编码序列(CDS)全长和编码氨基酸的数目分别在528-1122 bp和175-373 aa之间,命名为CsOMT1-CsOMT5.系统发育树分析显示,茶树OMT蛋白分别与已知的咖啡酰辅酶A-O-甲基转移酶、咖啡酸O-甲基转移酶、黄腐酚4-O-甲基转移酶和类黄酮3′,5′-甲基转移酶等具有较近的亲缘关系.基因结构分析结果显示,结构相似的OMTs成员多聚在同一个分支,这些结果与系统发育分析的结果一致.转录组结果表明,5个OMTs基因在富含甲基化EGCG的金观音和金牡丹中具有较高转录水平;实时荧光定量PCR表达分析显示,除OMT2之外,其余4个OMTs基因在3个茶树品种的相对表达水平差异显著,总体表现为在福鼎大白中表达量较低,而在金观音和金牡丹中相对表达水平显著上升.上述研究表明鉴定获得的CsOMT1、CsOMT3、CsOMT4和CsOMT5可能参与甲基化EGCG的生物合成,结果可为茶树甲基化EGCG生物合成的调控机制研究奠定理论基础.O-methyltransferase(OMT)catalyzes the biosynthesis of O-methylated EGCG in Camellia sinensis.To further obtain the key OMT genes for O-methylated EGCG biosynthesis,three tea cultivars including“Fudingdabai(FD)”,“Jinmudan(JMD)”,and“Jinguanyin(JGY)”with different O-methylated EGCG contents,were used as the experimental materials in this study.Based on the genomic and transcriptomic data of tea plants,the OMT genes were analyzed using bioinformatics methods for gene identification,chromosomal localization,gene structural characteristics,coding protein properties,and phylogenetic relationships,whereas real-time fluorescence quantitative polymerase chain reaction was used to verify the relative expression levels of OMTs in three tea plant cultivars.Results showed identified a total of five OMT genes whose expressions were significantly upregulated in“JGY vs FD”and“JMD vs FD”comparison groups.The full-length coding sequence and encoded amino acid numbers of these OMTs ranged from 528-1122 bp and 175-373 aa,respectively,and were named CsOMT1-CsOMT5.Phylogenetic tree analysis showed that these CsOMT proteins have close affinities with the known CCoAOMT,COMT,xanthohumol 4-O-methyltransferase,and flavonoid 3′,5′-methyltransferase.Gene structure analysis indicated that similarly structured OMT members clustered mostly in the same branch,and these results were consistent with the results of the phylogenetic analysis.Transcriptome data showed that five OMT genes had high transcript levels in the O-methylated EGCG-rich tea plant cultivars JGY and JMD.Gene expression analysis revealed that,except for OMT2,the relative expression levels of the remaining four OMT genes differed significantly among the three tea cultivars,which were expressed at a lower level in FD but were significantly increased in JGY and JMD.In summary,the identified CsOMT1,CsOMT3,CsOMT4,and CsOMT5 may be involved in the biosynthesis of O-methylated EGCG.This study provides a theoretical basis for understanding the mechanisms regulating

关 键 词：茶树 甲基化EGCG OMT基因 转录组 定量表达 

分 类 号：S571.1[农业科学—茶叶生产加工]