夜来香SAMT基因的分离与原核表达

为探究夜来香（Cestrum nocturnum）花香基因SAMT在花香代谢中的调控作用，以花瓣为材料，采用RT-PCR和RACE技术相结合，克隆夜来香SAMT基因的全长cDNA。结果表明：该cDNA的序列长度为1 493 bp，编码365个氨基酸，其中包含1 098 bp ORF、130 bp 5′UTR和265 bp 3′UTR，将其命名为CnSAMT；生物信息学分析结果表明：该基因所编码的氨基酸序列与烟草、番茄的同源性分别为98％和98％，属于甲基转移酶-7家族；原核表达结果表明：CnSAMT的蛋白表达产物约为42 ku，与软件预测的结果大致相同。采用染色体步移技术，克隆夜来香CnSAMT的5′端调控序列，结果表明：该序列长度为993 bp，且该序列除了含有TATA-box、CAAT-box等启动子核心元件外，还含有光、生长素、脱落酸、热胁迫、缺氧胁迫等外界环境条件响应的顺式作用元件。

Isolation and Prokaryotic Expression of SAMT Gene from Cestrum nocturnum

A full-length cDNA encoding SAMT named CnSAMT with length 1 493 bp, encoding 365 amino acids, including 130 bp 5′UTR, 1 098 bp ORF,  265 bp 3′UTR, was cloned by the combination of RT-PCR and RACE from Cestrum nocturnum petals, to explore the mechanism of the formation of fragrance in C. nocturnum. Bioinformatics analysis showed that the amino acid sequence was 98% homology with Nicotiana tabacum and 98% identity with Solanum lycopersicum, belonging to Methyltransf-7 superfamily. The product of prokaryotic expression of CnSAMT gene was about 42 ku. The molecular weight was consistent with the predicted by software. A regulatory sequence of the 5′ terminal in CnSAMT with 993 bp in length was cloned by genomic walking technology and the result of sequence analysis showed that the regulatory sequence contained core elements such as TATA-box, etc. and other cis-acting elements responding for environmental conditions such as light, auxins, ABA, heat stress and anaerobic tress, and so on.