Multi-Omics Analysis Of Aroma Formation In Jasmine(Jasminum Sambac)During Flowering

Jasmine tea belongs to reprocessed tea,which originated in Fuzhou,Fujian Province.It is made by mixing and scenting tea and jasmine to make tea absorb the aroma of jasmine.Jasminum sambac(L.)Aiton is the main raw material for scenting jasmine tea,and the difference in aroma characteristics of its varieties directly affects the aroma quality of jasmine tea.Single-petal jasmine(SP)and double-petal jasmine(DP)are the production species of jasmine tea.SP jasmine shows a fresh and pure aroma,low yield and weak resistance.DP jasmine shows a intense aroma,high yield and high resistance.In this study,widely targeted metabolomic were used to explore the aroma precursors in SP and DP.Metabolomics was used to analyze the aroma variation and characteristic aroma of those jasmines during flowering,and combined with transcriptome data,potential regulatory genes related to aroma formation were mined.In addition,the genome-wide identification and analysis of the TPS gene family involved in terpenoid metabolic pathway.This study elucidates the molecular mechanism of jasmine aroma formation from the molecular level,and provides theoretical basis for jasmine production and variety breeding.The main results were as follows:1.Analysis of different metabolites in flowers and leaves of different Jasminum sambacIn this study,the flowers and leaves of Fuzhou single petal(SP)and double petal(DP)jasmines were used as materials.Ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)was used to determine.A total of 935 metabolites(13 categories)were identified from the flowers and leaves of SP and DP.The main significant changed metabolites were phenolic acids,flavonoids,lipids,saccharides and sugar alcohols.Significant changed metabolites(SCMs)in flowers were mainly enriched in tryptophan metabolism,propanoate metabolism,photosynthesis,monoterpenoid biosynthesis,and biosynthesis of cofactor.In addition,this study found that more D-sucrose and D-trehalose accumulated in the flowers of SP,which may contribute to the aroma formation in SP.The significant accumulation of phosphoenolpyruvate and anthranilic acid in the flowers of DP,and the significant accumulation of3-dehydro-shikimic acid in the flowers of SP may be the reason for the differential accumulation of aromatic substances in the downstream of those jasmines.2.Volatile metabolome analysis of dynamic changes of aroma components of Jasminum sambac during floweringA total of 103 volatiles were identified from SP and DP jasmines by using HS-SPME-GC?MS,among which 16 volatiles were identified as their key odorants.Terpenoids,esters and alcohols were the main aroma components.The increasing trend of caryophyllene,α-farnesene,methyl anthranilate,benzyl acetate,benzeneacetaldehyde,hexanal,phenylethyl alcohol and the decreasing trend of linalool may contribute to the characteristic aroma of SP.The caryophyllene,geraniol,linalool,α-farnesene,methyl anthranilate,methyl salicylate,benzoic acid,methyl ester,benzyl acetate,benzeneacetaldehyde and hexanal in DP may contribute to the formation of variety characteristic aroma.In addition,the potential reason for the aroma difference between SP and DP during flowering may be the significant difference in the contents of β-ocimene,benzyl benzoate,methyl anthranilate,benzoic acid,methyl ester,phenylethyl alcohol and cis-nerolidol.3.Transcriptome analysis of aroma-related genes of Jasminum sambac during floweringIn this study,Illumina 6000 sequencing technology was used for transcriptome sequencing and differentially expressed genes(DEGs)analysis.A total of 156.39 Gb clean data were obtained,and 30167 genes were obtained after comparison and annotation.Analysis of DEGs in the terpenoid and phenylpropane/benzene metabolic pathways found that PMK1,MDS1 and TPS16,which were up-regulated in SP,and HMGR1,HMGR2,HDR2,DXS3,DXS4,TPS1,TPS9,TPS15,TPS19,PAL1,PAL3,4CL1 and 4CL2,which were highly expressed during flowering in DP,may play an important role in the synthesis of terpenoids and benzene/phenylpropanoids.WGCNA analysis showed that b ZIP8 may be involved in the biosynthesis of geraniol and linalool in jasmine by regulating the expression of TPS15 and TPS19;b HLH6,MYB4 and AP2/ERF3 may affect the accumulation of benzyl benzoate by regulating the expression of PAL1.4.Genome-wide identification of TPS gene family of Jasminum sambac and its expression during floweringIn this study,TPS genes were identified from the chromosome-level genome of DP,and a total of 26 full-domain Js TPS genes were identified.The Js TPS genes were distributed unevenly on 6 chromosomes and mainly located in cytoplasm or chloroplast.By analyzing the expression pattern of Js TPS genes of Jasminum sambac during flowering,it was found that Js TPS1,Js TPS4,Js TPS9,Js TPS24 and Js TPS31 were highly expressed in SP and DP,and the expression of Js TPS1,Js TPS24 and Js TPS31 in DP was significantly higher than that in SP.The expression of Js TPS2 and Js TPS16 in SP was significantly higher than that in DP,indicating that these Js TPS genes may play an important role in the accumulation and difference of terpenoids during flowering in SP and DP.