佛手瓜β-香树素合成酶基因表达及齐墩果烷型皂苷的分析

Expression ofβ-amyrane gene and analysis of oleanolic saponins in Sechium edule

佛手瓜为贵州省9个优势蔬菜单品之一,含有齐墩果烷型皂苷。β-香树素合成酶(β-AS)是2,3-氧化角鲨烯物质转化成齐墩果烷型皂苷关键酶。本研究利用转录组数据并克隆获得了1条完整的佛手瓜β-AS基因(GenBank登录号MW123089),该基因开放阅读框长度为2370 bp,可编码氨基酸长度为789 aa。进化分析表明,佛手瓜β-AS与葫芦科植物处在一个分枝,但存在一定的距离。基因表达结果表明,β-AS基因在佛手瓜嫩果中表达最高,而在成熟的老果中表达量相对较低。利用LC-MS非靶向代谢组学研究发现了佛手瓜中有6种齐墩果烷型皂苷,总含量在小果(5.175 mg·100 g^(−1))和嫩果(4.811 mg·100 g^(−1))中较高。

Sechium edule is one of the nine dominant vegetable products in Guizhou Province.Previous studies have shown that S.edule contains oleanane saponins.β-amyrin synthase(β-AS)is the key enzyme for transforming 2,3-oxsqualene into oleanane saponins.In this study,a completeβ-AS gene(GenBank:MW123089)was cloned based on the transcriptome data.The ORF frame length of the gene was 2370 bp,encoding amino acid length was 789 aa.Phylogenetic analysis showed thatβ-AS of S.edule could be in a branch with other Cucurbitaceae plants,but there was a certain distance between them.Gene expression analysis showed that the expression level ofβ-AS gene was the highest in young fruit,but relatively low in mature old fruit.Six oleanane saponins were found in the fruits of S.edule by LC-MS non-targeted metabonomics,and the total content was high in small(5.175 mg·100 g^(−1))and tender(4.811 mg·100 g^(−1))fruit.