目的 基于人参转录组数据库鉴定环阿屯醇合酶基因（cycloartenol synthase，CAS）家族成员（PgCAS），并分析PgCAS04-5 在过表达及RNAi阳性发根材料中基因的表达模式及人参皂苷生物合成中的功能。方法 利用生物信息学分析了PgCASs的染色体定位、保守基序、进化关系、表达模式、与皂苷合成关键酶基因表达及单体皂含量的相关性；预测PgCAS04-5的蛋白结构与亚细胞定位，同时检测PgCAS04-5在过表达及RNAi阳性发根中关键酶基因的表达情况及皂苷含量变化。结果 在人参转录组数据库中鉴定出20条PgCAS转录本，染色体定位结果表明PgCASs不均匀地分布在人参5条染色体上，构建进化树将PgCASs分为3个亚型，PgCASs主要分布在第Ⅱ和第Ⅲ个亚型中。PgCASs在不同品种、生长年限及组织中的表达模式存在时空特异性，且该家族与皂苷合成关键酶基因形成互作网络并与单体皂苷含量显著相关。PgCAS04-5的亚细胞定位为叶绿体，同时该基因的过表达与RNAi阳性材料中PgCAS04-5、PgDS-1、PgSE2-4、PgCYP137 这4个基因的表达呈反向调控，差异显著。结论 鉴定出20个PgCAS家族成员，PgCAS家族成员功能存在分化，PgCAS04-5基因正向调控人参皂苷Rg₂和人参皂苷Rf的合成，同时负向调控人参皂苷Rb₂和人参皂苷Rd的生物合成，为进一步研究PgCAS基因家族提供参考。

Objective To identify members of the cycloartenol synthase (CAS) gene family (PgCAS) using the Panax ginseng transcriptome database, and analyze the expression patterns of PgCAS04-5 in overexpressed and RNAi-positive hair root materials), as well as explore the function of this gene in ginsenoside biosynthesis. Methods Bioinformatics approaches were adopted to characterize the chromosomal localization, conserved motifs, phylogenetic relationships and expression profiles, and the correlations with the gene expression of key saponin synthesis enzymes and the content of monomer saponin of PgCASs. The protein structure and subcellular localization of PgCAS04-5 were predicted. Meanwhile, the expression levels of key enzyme genes and variations in ginsenoside contents were detected in overexpression and RNAi-positive hairy root lines. Results A total of 20 PgCAS transcripts were identified from the P. ginseng transcriptome database. Chromosomal mapping showed that PgCAS genes were unevenly distributed on five chromosomes of P. ginseng. Phylogenetic tree analysis divided the PgCAS family into three subfamilies, and most PgCAS members belonged to subfamily Ⅱ and subfamily Ⅲ. The PgCAS genes displayed obvious spatiotemporal specificity in expression across different cultivars, growth years and tissues. Additionally, the PgCAS family formed an interaction network with key genes involved in ginsenoside biosynthesis, and their content was significantly correlated with the accumulation of monomeric ginsenosides. Subcellular localization prediction demonstrated that PgCAS04-5 was localized to chloroplasts. Moreover, the overexpression of this gene was inversely regulated with the expression of four genes including PgCAS04-5, PgDS-1, PgSE2-4 and PgCYP137 in RNAi positive materials, with significant differences. Conclusion A total of 20 members of the PgCAS gene family were identified in this study, and functional differentiation exists among PgCAS family members. PgCAS04-5 positively regulates the biosynthesis of ginsenosides Rg₂and Rf, and negatively modulates the synthesis of ginsenosides Rb₂and Rd. The results provide a valuable reference for further research on the PgCAS gene fami

R282.12

人参基因育种技术的建立及优良农家品种选育（20250205032GH）