汉麻聚酮合酶基因家族成员鉴定与表达分析

Identification and expression analysis of Polyketide synthase gene family in Cannabis sativa

目的在从全基因组层面对汉麻Cannabis sativa聚酮合酶(polyketide synthases,PKSs)基因家族进行鉴定和功能分析,为解析汉麻次生代谢产物的合成与积累奠定理论基础。方法基于已发布的高质量汉麻基因组,利用生物信息学工具对汉麻PKS基因家族进行鉴定并对其物化性质、基因结构、蛋白构象以及表达模式进行分析,利用Alphafold算法对关键PKS蛋白结构进行预测。结果共鉴定出9个汉麻PKSs(CsPKS1~CsPKS9),分布在5条染色体上。通过对汉麻和其他物种PKS的系统发育分析,CsPKSs主要被分为3组:group1包括Cs PKS2~CsPKS4与花药特异性CHS样酶(anther specific chalcone synthase-like,ASCL)同源;group2含有CsPKS1和CsPKS5~CsPKS8为类CHS超家族(chalcone synthase like,CHSL)与苯戊酮合酶(valerophenone synthase,VPS)和茋类合酶(stilbene synthase,STS)等关系较密切;group 3仅含有CsPKS9,为查耳酮合成酶(chalcone synthase,CHS)参与类黄酮的合成。其中,CsPKS1和CsPKS7串联重复,是汉麻中酚萜类化合物合成通路中的橄榄醇合成酶(olivetolsynthases,OLS)。此外,CsPKS5和CsPKS8可能参与汉麻茋类化合物的生物合成。CsCHS的功能在进化中相对保守,而CHS-like的CsPKS的功能出现了分化。通过对汉麻不同组织部位和不同品种腺毛的RNA-seq数据分析,汉麻PKSs基因的表达存在组织特异性,尤其与酚萜类、类黄酮、茋类次生代谢产物密切相关的基因在雌花和苞片中特异性表达。结论为深入研究汉麻PKS基因家族的功能提供了方向,为进一步阐明汉麻中萜酚类化合物的生物合成机制和CsPKSs在汉麻中的生理功能奠定基础,并对开发新聚酮化合物药用资源提供理论基础。

Objective To conduct identification and functional analysis of the polyketide synthase(PKS)gene family of Hanma(Cannabis sativa L.)from the genome-wide level as a theoretical basis for resolving the synthesis and accumulation of secondary metabolites in Cannabis sativa L.Methods Based on the published high-quality C.sativa genome,the C.sativa PKS(CsPKS)gene family were identified and its physicochemical properties,gene structure,protein conformation and expression pattern were analyzed through bioinformatics analysis tools,in addition,this study also used the Alphafold algorithm to predict the key PKS protein structure.Results A total of nine CsPKS members(CsPKS1-CsPKS9)were identified in this study and they distributed on five chromosomas.Through the phylogenetic analysis of CsPKSs in C.sativa along with other species,CsPKSs are mainly divided into three groups.Group1 contains Cs PKS2-CsPKS4 are homologous to anther specific chalcone synthase(CHS)-like(ASCL)enzymes;Group2 contains CsPKS1 and CsPKS5-CsPKS8,which belongs to the CHS-like superfamily(CHSL)and is closely related to valerophenone synthase(VPS)and stilbene synthase(STS);Group3 contains only Cs PKS9,a CHS involved in the synthesis of flavonoids.Among them,CsPKS1 and CsPKS7 are tandem repeat genes,which are olivetol synthases(OLS)in the synthesis pathway of phenolic terpenoids in hemp,CsPKS9 is the CHS of the hemp flavonoid synthesis pathway and is involved in the synthesis of flavonoids.In addition,CsPKS5 and CsPKS8 may be involved in the biosynthesis of stilbene compounds.The functions of CsCHS are relatively conserved in evolution,while the functions of CHS-like have diverged.According to RNA-seq data,CsPKSs were differentially expressed in five tissues in cultivar Diku,especially the genes closely related to phenolic terpenoids,flavonoids,and stilbene secondary metabolites in specific expression in female flowers and bracts.Conclusion This study will provide a direction for further functional study of the CsPKS gene family,lays a foundation for further elucidating the biosynthetic mechanism of terpene phenolic compounds in C.sativa and the physiological function of CsPKSs,and provides theoretical basis for the development of new polyketides for medicinal resource.