中文摘要：

【目的】从茶树中克隆甜菜碱（GB）合成途径中的关键酶——胆碱单加氧酶CsCMO,研究不同逆境胁迫和不同抗寒茶树品种间GB合成中关键基因的表达模式,并分析茶树体内GB的含量,为茶树抗性育种奠定基础。【方法】采用反转录PCR结合RACE技术,从茶树中克隆CsCMO的全长cDNA序列,并对其进行生物信息学分析,结合前期克隆得到的茶树甜菜碱醛脱氢酶CsBADH,用实时荧光定量PCR（qRT-PCR）方法分析这2个基因的表达模式,紫外分光光度计测定GB含量。【结果】克隆得到茶树CsCMO（GenBank登录号：JX050146）的cDNA全长1 558 bp,包含1 305 bp的完整开放阅读框（ORF）,编码434个氨基酸,并被定位在叶绿体上。氨基酸序列分析表明,CsCMO含有CMO中保守的Rieske型2Fe-2S结构域和单分子非血红素Fe结合位点,与其它植物CMO序列相似性在50%以上;进化树分析显示,它与枸杞的关系最近。qRT-PCR分析表明,4℃低温、NaCl盐和ABA处理均能诱导CsCMO和CsBADH表达,96 h内随着处理时间的增加,表达量呈增加趋势,但2个基因的表达模式有差异,盐胁迫诱导基因表达更显著;在不同抗寒品种中,2个基因的表达在抗性强的品种中表达量总体要高于抗性弱的品种,且CsBADH的变化比CsCMO的显著。3种胁迫处理48 h后,叶片中的GB含量均增加;低温处理后抗寒性强的品种中GB含量比抗寒性弱的高。【结论】克隆了茶树CsCMO,在低温、NaCl盐以及ABA处理下,GB积累,CsBADH和CsCMO上调表达,且盐胁迫下的表达更明显,表明GB与茶树抵御这3种胁迫关系密切。

英文摘要：

【Objective】 Choline monooxygenase gene（CMO）,one of the key enzyme genes in biosynthesize pathway of glycine betaine（GB） in plant,was cloned from tea plant（Camellia sinensis）.The expression patterns of CsCMO and the other GB biosynthesis-related gene,CsBADH（betaine aldehyde dehydrogenase）,under different abiotic stresses and in different cold resistant cultivars were analyzed.And the contents of GB under different abiotic stresses in tea plant were detected.【Method】 The full-length cDNA of CsCMO was isolated using reverse transcription-PCR（RT-PCR） combined with RACE techniques from tea plant,and the bioinformatic characteristics were analyzed using online software.The expression profiles of CsCMO and CsBADH and the contents of GB were determined using quantitative real-time PCR（qRT-PCR） method and ultraviolet spectrophotometer techniques,respectively.【Result】 The obtained cDNA of CsCMO was 1 558 bp in length with GenBank accession number JX050146,containing a 1 305 bp open reading frame（ORF） which encoded 434 amino acid residues.The CsCMO shared more than 50% amino acid sequence similarity with that of other plants.It was targeted in chloroplast and contained two consensus domains of Rieske-type [2Fe-2S] cluster and sites for mononuclear nonheme Fe.The phylogenetic tree analysis showed that CsCMO had the closest genetic relationship with Lycium barbarum.The qRT-PCR analysis indicated that the expressions of CsCMO and CsBADH were up-regulated by cold（4℃）,salt（NaCl） and abscisic acid（ABA） during 96 h treatment,but they displayed different patterns under these stresses.The expression level of two genes induced by NaCl was more dramatically than other treatment.The further experiments showed that the level of CsBADH was generally higher than CsCMO in different cold tolerance cultivars,and the cultivars which had stronger cold hardiness had higher expression level of CsCMO and CsBADH than that of the cultivars which had weaker cold hardiness.The accumulation of GB w