| Taxus wallichiana var.mairei is an important drug source plant,and its high-value natural anticancer substance taxol as well as other active ingredients have attracted wide attention from scientists all over the world.Taxus wallichiana var.mairei cv.‘Jinxishan’is a natural variant strain of Taxus wallichiana var.mairei with yellow aril and high taxol content.The study on its metabolism and regulation mechanism provides a theoretical basis for the comprehensive development and utilization of Taxus wallichiana var.mairei.In this paper,widely targeted metabolomics combined with HPLC were used to study the difference of metabolites content in the needles of Taxus wallichiana var.mairei and Taxus wallichiana var.mairei cv.’Jinxishan’,which analyzed the special metabolic pattern of Taxus wallichiana var.mairei cv.’Jinxishan’.Then,key influencing factors for the regulation of taxol synthesis in Taxus wallichiana var.mairei cv.’Jinxishan’ were revealed by Transcriptome sequencing.The main research contents and results were as follows:1.Widely targeted metabolomics combined with HPLC were used to study the difference of metabolites content in the needles of Taxus wallichiana var.mairei(T.mairei)and Taxus wallichiana var.mairei cv.’Jinxishan’(T.’Jinxishan’).A total of 689 metabolites were found,of which 71 metabolites content was significantly difference.Most of differential metabolites between T.mairei and T.’Jinxishan’ were significant enriched in primary metabolic pathways,such as glycometabolism and lipid biosynthesis pathways,as well as secondary metabolic pathways such as flavonoids biosynthesis pathways.A large number of metabolites in the flavonoid and amino acid biosynthesis pathway were significantly accumulated in T.’Jinxishan’,while the differential metabolites in sugar metabolism,lipid synthesis and TCA cycle pathways were mainly accumulated in T.mairei.The increase of flavonoid content was related to the increase of 3-O-p-Coumaroyl quinic acid content in the upstream,suggesting that the increase of flavonoid metabolites content may be attributed to the co-regulation of phenylalanine and tyrosine metabolic pathways,which improved the adaptability of T.’Jinxishan’ to the environment.At the same time,the energy was supplyed by synthesizing large amounts of amino acids to make up for the lack of energy,caused by the decrease of metabolites content in glycometabolism,lipid biosynt hesis and TCA cycle pathways.2.To investigate the key influencing factors for the regulation of taxol biosynthesis in T.’Jinxishan’,RNA-seq was conducted to reveal the differences in transcriptional levels between T.mairei and T.’Jinxishan’.Compared with T.mairei,the results indicated that there are 2,889 up-regulated differentially expressed genes and 2,347 down-regulated differentially expressed genes in the needles of T.’Jinxishan’.Among them,high expression levels of unigenes encoded for taxadienol acetyltransferase(TAT),taxadiene 5-alpha hydroxylase(T5H),5-alpha-taxadienol-10-beta-hydroxylase(T10OH),and 2-debenzoyl-7,13-diacetylbaccatin III-2-O-benzoyl-transferase(DBBT),which catalyze the key acetylation and hydroxylation steps,are the main cause of high taxol content in T.’Jinxishan’.Moreover,Our RNA-seq data showed that COI1 and JAZ-encoding genes had significantly increased transcript abundance,resulting in the activation of Jasmonic acid(JA)signal transduction in the needles of T.’Jinxishan’,and its crosstalk with the relevant genes in the hormone signal pathway of Gibberellin(GA),auxin,and Ethylene(ET)(such as DELLA,ERF1,ARF,etc)finally caused the increase of taxol content,which explains the elevation of differentially expressed genes(DEGs)in the taxol biosynthesis pathway.TFs-encoding(transcription factor)genes,represented by the transcription factor(ERF),basic/helix-loop-helix(bHLH),MYB,and WRKY families,were detected as differentially expressed between JXS and WT,further indicated that the regulation of hormone signaling on taxol biosynthesis genes were mediated by transcription factors(TFs). |
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