毛白杨蔗糖合酶基因PtSS2克隆与表达分析

Molecular Cloning and Expression Patterns of PtSS2fromPopulus tomentosa

为了解毛白杨蔗糖合酶（sucrose synthase,SS）基因功能和表达模式,以毛白杨茎段来源的cDNA为模板,根据毛果杨PtrSS2 CDS 序列信息设计特异引物,采用RT-PCR技术分离克隆了PtSS2基因。测序分析表明,PtSS2基因序列全长为2 412 bp,编码803个氨基酸,蛋白大小为92.14 kD,理论等电点6.00,属于酸性蛋白;氨基酸序列同源性分析表明,PtSS2与毛果杨PtrSS2和PtrSS1一致性分别高达100%和98.63%;结构域分析表明,PtSS2含有2个高度保守的功能域,即蔗糖合酶（5~552）和糖基化转移酶（554~744）功能域。qRT-PCR 检测表明,PtSS2在毛白杨根、茎、叶、营养芽、雄雌花芽等各个组织中均有表达,但在营养芽和花芽中表达量较高,根部相对较低,总体呈组成型表达模式;在干旱胁迫下,PtSS2表达水平提升。研究结果推测,蔗糖合酶基因PtSS2在毛白杨各组织器官发育过程及干旱胁迫响应过程中具有重要功能。

To investigate the function and expression patterns of sucrose synthase gene,we used cDNA reverse transcript from total RNA of stem tissue of Populus tomentosa as DNA template.The specific-primers were designed according to PtrSS2 CDS on Phytozome v9.0 database for PCR amplification.The sequencing results indicated that PtSS2 was 2 412 bp in full length which encoded a protein of 803 aa.Its molecular weight and isoelectric point （pI） were 92.14 kD and 6.00,respectively.The result showed that the PtSS2 in P.tomentosa belonged to acidic protein.The deduced protein sequence of the PtSS2 shared 100% and 98.63% highly identify with PtrSS2 and PtrSS1,respectively.Conserved domain searching results showed that this protein contained two conserved function domains,5~552 and 554~744.Tissue differential expression detected with qRT-PCR indicated that the PtSS2 transcripts were more abundant mRNA products in vegetative bud and stem tissue,and relative lower transcripts in root,it belong to constitutive expression patterns.RT-PCR showed that levels of mRNAs to drought stress were significantly higher than that in control group.The results suggested that PtSS2 gene play a role in the development of P.tomentosa plant.