目的 克隆获得洋常春藤Hedera helix鲨烯合成酶基因（HhSS）cDNA全长序列并进行生物信息学分析及表达分析。方法 根据洋常春藤转录组数据信息设计引物，通过RACE克隆方法获得HhSS基因序列；采用DNAMAN、PROTPARAM、TMHMM、PSORT、ScanProsite、SOPMA、SWISS-MODEL等生物信息学工具分析序列信息及编码蛋白的理化特性、结构域等特征；通过实时荧光定量PCR（qRT-PCR）技术进行HhSS基因的检测分析。结果 RACE克隆获得HhSS（GenBank登录号KX056078）基因cDNA序列全长1 889 bp，包含一个从248～1 477 bp的完整开放阅读框（ORF）以及247 bp的5’非编码区（5’UTR）和412 bp的3’非编码区（3’UTR）。该基因编码409个氨基酸，相对分子质量为46 800，等电点为5.68。HhSS蛋白具有植物SS蛋白的特征结构域和跨膜区，与刺五加、人参等同科植物亲缘关系较近。qRT-PCR结果表明洋常春藤叶片中HhSS基因的相对表达量与常春藤皂苷含量存在正相关性。结论 洋常春藤HhSS基因的成功克隆及表达分析研究，为阐明HhSS基因在常春藤皂苷生物合成途径中的作用及代谢调控研究提供理论依据和技术基础。

Objective To obtain a full-length cDNA of squalene synthase gene from Hedera helix (HhSS) by cloning technique, and to carry out bioinformatics analysis and expression analysis.Methods Primers were designed based on H. helix transcriptome data, and HhSS was cloned by using RACE technologies.DNAMAN, PROTPARAM, TMHMM, PSORT, ScanProsite, SOPMA, and SWISS-MODEL were used for analysis of sequence and physical and chemical properties and domain of encoded protein.The relative expression of HhSS was detected by qRT-PCR.Results The cDNA sequence of HhSS (GenBank accession number:KX056078) was 1 889 bp which obtained by RACE cloning.It contained an ORF from 248 bp to 1 477 bp and a 5'UTR with 247 bp and a 3'UTR with 412 bp.It encoded a 409-amino-acid protein with a molecular weight of 46 800and an isoelectric point (pI) of 5.68.The HhSS protein had the characteristic domain and transmembrane region of plant SS protein and closer relationship with Eleutherococcus senticosus, Panax ginseng et al.The qRT-PCR results indicated that it had positive correlation between relative expressing level of HhSS gene and contents of saponins in H. helix leaves.Conclusion The cloning and expression analysis results of HhSS provide a theoretical and technical basis for elucidating the role of HhSS in saponins biosynthetic pathway and metabolic regulation.

中国热带农业科学院基本科研业务费专项资金（1630032018006）；湖南省教育厅科研项目（15A089）