【摘要】 三萜皂苷是三七、人参等重要药用植物的主要有效成分.采用改进的异硫氰酸胍法提取到三七RNA,经RT-PCR克隆技术获得三七三萜合成通路关键酶之一鲨烯合酶(squalene synthase,SS)cDNA,长1270 bp,读码框架编码415个氨基酸.比对分析表明,推衍的三七SS氨基酸序列与人参、积雪草、青蒿、拟南芥和水稻SS的一致性分别为98%、89%、81%、78%和71%.利用实时荧光定量RT-PCR技术对三七根、茎、芦头的SS转录表达研究发现,一年生三七根SS基因转录表达量最高,高于茎和芦头的表达;但总皂苷含量是:芦头>叶>根>茎.可能与SS之后其它三萜合成关键酶的活性差异或/和三萜合成后的定向输送及累积有关.更多还原

【Abstract】 Triterpenoids are the principal effective components of various important Chinese traditional medicines such as Sanqi(Panax notoginseng) and Ginseng(Panax ginseng),etc.Sanqi total RNA were extracted with improved guanidine thiocyanate method,and cDNA of squalene synthase(SS),one of key enzymes on the triterpenoid synthesis pathway in plants from Sanqi root was cloned.The cDNA length of SS from Sanqi is about 1270 bp with one open-reading frame encoding 415 amino acids.Multiple alignment result shows that the deduced Sanqi SS amino acid sequence exhibits about 98%,89%,81%,78% and 71% identity to the SSs of Panax ginseng,Centella asiatica,Artemisia annua,Arabidopsis thaliana,Oryza sativa,respectively.The transcription expression analysis with SYBR Green I Real Time RT-PCR and GAPDH as internal control reveals that the SS expression level in Sanqi root is higher than in stem and rootstock.The amount of total triterperoids in rootstock is higher than in leaf,root,stem in order,perhaps involved in the expression differences of other key enzymes after SS on the triterpenoid synthesis pathway or/and the directional transportation and accumulation of triterpenoid in different tissues and organs of plants.更多还原