两个水稻GDP-甘露糖-3′, 5′-异构酶基因特征及表达模式的研究  

Molecular Characterization of Two Rice cDNAsEncoding GDP-Mannose-3′, 5′-Epimerase and Their Expression Patterns

作　　者：杜盈[1] 姚远[1] 刘进元[1] 

机构地区：[1]清华大学生物科学与技术系分子生物学实验室及教育部蛋白质科学重点实验室,北京100084

出　　处：《生物化学与生物物理进展》2006年第4期368-376,共9页Progress In Biochemistry and Biophysics

基　　金：国家自然科学基金资助项目(30270753);国家重点基础研究发展计划项目(973)(2004CB117303);国家高技术研究发展计划(863)资助项目(2004AA222100,2002AA212051和2002AA207006).

摘　　要：GDP-甘露糖-3',5'-异构酶(GME)可以催化GDP-甘露糖转化为左旋GDP-半乳糖,该反应对于高等植物体内抗坏血酸的合成是非常重要的.但目前在分子水平上还没有对GME基因进行研究的报道.通过逆转录PCR(RT-RCR)技术从水稻成熟叶片中克隆到两个GME基因的cDNA序列,并与其他植物物种中的GMEs进行比对,结果显示,GME基因在所有植物物种中高度保守,尽管进化树分析表明单子叶植物GMEs和双子叶植物GMEs在进化上相互独立.同时,分析这两个水稻GME基因的剪切模式揭示了二者也存在高度相似性.采用半定量RT-PCR技术对两个GME基因在不同组织和不同胁迫条件下的表达模式进行研究表明,OsGME1基因在冷胁迫条件下表达水平上调,这和先前水稻冷胁迫蛋白质组学研究的结果是一致的.而OsGME2和OsGME1基因在用赤霉素处理条件下表达水平均下调,暗示赤霉素可能通过调节GME基因的表达来调控植物体内的抗坏血酸合成.GDP-mannose-3＇, 5＇-epimerase （GME）, which converts GDP-mannose into GDP-L-galactose, is essential for the biosynthesis of L-ascorbic acid in higher plants. The molecular characterization of two GME genes from rice has been reported. Firstly, both cDNAs were isolated from the rice mature leaves using RT-PCR technique. By comparing their sequences with homologues from other plants, it was found that GME genes were highly conserved among plant species, though phylogenetic study showed that all known GMEs could be divided into two distinct groups corresponding to monocots and dicots. Secondly, the genomic organization of rice OsGME genes was investigated, and a similarity of splice patterns was revealed. Finally, the expression patterns of the two cDNAs have been studied in various tissues and under different stress conditions by semiquantitative RT-PCR assay. The results showed that the OsGME1 transcript was up-regulated in response to cold stress, and gibbereUin might regulate L-ascorbic acid levels by affecting transcription of both OsGME genes.

关 键 词：植物抗坏血酸合成 基因表达 半定量RT-PCR技术 

分 类 号：Q52[生物学—生物化学]