摘要
在盐和干旱等渗透胁迫条件下,一些植物会积累甘氨酸甜菜碱(简称甜菜碱)作为渗透调节物质,甜菜碱在植物体内由胆碱经两步氧化形成,催化这两步反应的酶分别是胆碱单氧化物酶(cholinemonooxyge-nase,CMO)和甜菜碱醛脱氢酶(betainealdehydedehydrogenase,BADH)。由于甜菜碱的合成途径简单,进行遗传操作方便,在诸多抗逆性基因中甜菜碱合成酶基因被看作是最有希望的胁迫抗性基因。其中,BADH基因的全长cDNA序列首先被从藜科植物菠菜(Spinaciaoleracea)中克隆到,此后人们相继以该基因为参照,研究其它植物中的BADH基因。本文作者在以菠菜BADH基因为对照研究菊科植物的BADH基因时,根据已发表BADH基因的保守区序列设计了一对PCR兼并引物,以菠菜基因组DNA为模板,采用PCR法扩增出长分别为825bp(seq1)和822bp(seq2)的两个DNA片段,经测序和序列分析,seq1与GenBank中登录的菠菜BADH基因的基因组序列(U69142)一致,其外显子区与已发表的该基因的cDNA序列(M31480)一致,seq2与U69142序列的同源性为68%,其外显子区与M31480序列的同源性为83.93%。而且,在由该核苷酸序列推导的氨基酸序列中,含有醛脱氢酶高度保守的十肽VTLELGGKSP,说明该基因为菠菜BADH基因的同源基因。根据现有文献分析,菠菜中可能存在两个BADH的同工酶,作者所克隆基因片段所属的基因可能编码菠菜BADH的另一个同工酶。该序列已在GenBank中登录,登录号:DQ070842。
When subjected to salt stress or drought, some plants respond with an increased accumulation of the osmoprotectant glycine betaine （betaine）. In these plants, betaine biosynthesis occurs by a two-step oxidation of choline, which are catalyzed by choline monooxygenase （CMO） and betaine aldehyde dehydrogenase （BADH）. Because of the simpleness of the biosynthetic pathway and the conveniency of genetic operation, the genes encoding the two enzyme are regarded as the most promising genes of resistance. The first full-length cDNA of BA DH gene was cloned from spinach of the Chenopodiaceae. Then the gene was often taken as a contrast when BA DH genes from other plants were studied. When studying the BA DH genes from Compositae plants, using the spinach BADH gene as a contrast, a pair of degeneracy primers was designed according to the conserved sequences of the published betaine aldehyde dehydrogenase genes （BA DH）, and two fragments were amplified by polymerase chain reaction （PCR） using the genomic DNA of spinach as a template. One fragment （seql） is 825bp in length, and the other （seq2） is 822bp. Seql is identical to the published genomic sequence ofBADH gene from spinach in GenBank （U69142）, and its exon is identical to the published cDNA sequence （M31480）. While seq2 is only 68% identical to the genomic sequence, and 83.93% identical to the cDNA sequence. In addition, the deduced amino acid sequence comprises the conserved decapeptide sequence （VTLELGGKSP） among aldehyde dehydrogenase. All of the information indicates seq2 belongs to a homologous BA DH gene of spinach. According to the published data, the gene which containes seq2 is likely to encode another isoenzyme of BADH from spinach. Seq2 has been registered on GenBank （DQ070842）.
出处
《分子植物育种》
CAS
CSCD
2006年第1期35-40,共6页
Molecular Plant Breeding
基金
北京市自然科学基金项目（5022008）
国家自然科学基会项目（30471419）资助.
关键词
菠菜
BADH基因例源片段
克隆
Spinach, Homologous fragment of BA DH gene, Cloning
