基于全基因组的栀子花香成分合成TPS基因系统分析

Systematic analysis of TPS genes for the synthesis of floral aroma components of Gardenia jasminoides J.Ellis based on the whole genome

栀子(Gardenia jasminoides J.Ellis)花色洁白且香气怡人,不仅具有极高的观赏价值,还是重要天然香料来源。萜类是栀子花独特香气的主要组成成分,但合成该类挥发性产物的关键萜类合酶(TPS)尚未鉴定。本研究基于栀子高质量基因组,通过转录组数据、系统发育树和保守结构域分析等,全面挖掘栀子萜类花香成分合成相关的TPS基因。结果显示,栀子基因组共注释到44个GjTPS基因,不均匀分布于11条染色体,其中9个GjTPS参与串联复制事件。所有GjTPS被划分为5个亚家族,其中27个属于被子植物特有的TPS-a、TPS-b和TPS-g分支。结合栀子5个器官的转录组数据及实时荧光定量PCR分析,筛选出5个候选GjTPS基因,其在盛开期的花器官中特异高表达,且含有DDXXD和NSE/DTE活性基序。其中,GjTPS1、GjTPS2、GjTPS3和GjTPS27为TPS-b分支酶,推测为芳樟醇或罗勒烯等栀子主要花香成分合成酶,而TPS-a分支的GjTPS18可能是金合欢烯合酶。

Gardenia jasminoides J.Ellis flowers are white in color and have a pleasant aroma.These flowers have high ornamental value and are an important source of natural spices.Terpenes are the main components of the unique aroma of G.jasminoides flowers,but the key terpene synthases(TPSs)for the biosynthesis of such volatile products have not yet been identified.Here,based on the high-quality genome of G.jasminoides,this study comprehensively explored the TPS genes related to floral scent biosynthesis through transcriptomic,phylogenetic,and conserved domain analysis.In total,44 GjTPS genes were identified in G.jasminoides,unevenly distributed on 11 chromosomes,and nine GjTPS genes participated in tandem duplication events.All GjTPSs were clustered into five subfamilies,27 of which belonged to the angiosperm-specific clades,including TPS-a,TPS-b,and TPS-g.Combining transcriptomic data and quantitative real-time PCR(qRT-PCR)analyses of five organs,five candidate GjTPS genes,with high expression in blooming flowers and containing the active motif DDXXD and NSE/DTE,were screened.Among them,GjTPS1,GjTPS2,GjTPS3,and GjTPS27 were grouped in the TPS-b clade,speculated to be the TPSs responsible for the biosynthesis of the main floral aroma components of G.jasminoides,such as linalool and ocimene,while GjTPS18 from the TPS-a clade may be a farnesene synthase.