The Comparative Effects Of Ethylene And Methyl Jasmonate On Secondary Metabolism And Anticancer Characteristics Of Catharanthus Roseus

The medicinal plant Catharanthus roseus produces a large number of terpenoid indole alkaloids(TIAs)used as chemotherapeutics in the treatment of lymphoma,leukemia.Secondary metabolic networks and regulation are becoming more and more attentional and in-depth researched.C.roseus is currently recognized as a model plant for studying the secondary metabolic pathways of terpene indole alkaloids.Elucidation of the synthetic pathway of these medicinal ingredients,the key enzymes involved in the synthesis and the regulation mechanism of transcription factors have become the targets of the current research.In this paper,C.roseusseedlings were treated with ethylene and methyl jasmonate,and their secondary metabolism regulation and anticancer characteristics were compared.The metabolites and transcriptome of alkaloids and phenols were determined and analyzed by UPLC-QTOF/MS and RNA-seq techniques.And we discuss the difference between the effects of two signaling molecules on the metabolism of terpene indole alkaloids and the regulatory network in C.roseus.The medicinal plant C.roseus accumulates large numbers of terpenoid indole alkaloids(TIAs),including the pharmaceutically important vinblastine,vincristine,ajmalicine,and serpentine.The phytohormone ethylene or methyl jasmonate(MeJA)can markedly enhance alkaloid accumulation.The interaction between ethylene or MeJA in the regulation of TIAs biosynthesis in C.roseus is unknown.Therefore,in this study,LC-MS was used to analyze alkaloid metabolites in C.roseus,and multivariate data were processed to screen out the key metabolites and 7 target TIAs target compounds in the alkaloid biosynthesis pathway.The relationship between secondary metabolites and upstream pathway metabolites in C.roseus under the action of exogenous hormones was further elucidated.Interestingly,ethylene and MeJA regulate the 2-C-methyl-D-erythritol 4-phosphate(MEP)and acetate-mevalonate(MVA)pathways through A ACT and HMGS and through DXS,respectively,to induce TIAs biosynthesis in C.roseus.Overall,both untargeted and targeted metabolomics,as well as transcript analysis,were used to reveal that MeJA and ethylene control different metabolic networks to induce TIAs biosynthesis.The medicinal plant C.roseus contains a large amount of phenolic compounds,and has various pharmacological effects,the exogenous hormones closely regulate the metabolic network in the plants.In this study,we approached the combinational effects of ethylene and methyl jasmonate(MeJA)on phenolic compounds profiles and gene expressions in the medicinal plant C.roseus.In virtue of a widely non-targeted/targeted metabolomics method,we identified a total of 29 kinds of phenolic compounds in the leaves.In addition,7 kinds of intermediates critical for the biosynthesis of phenolic compounds and alkaloids were identified and discussed with phenolic metabolism.The combinational actions of ethylene and MeJA effectively promoted the total phenolic compounds,especially the C6C1 compounds(such as salicylic acid,benzoic acid)and C6C3 ones(such as cinnamic acid,sinapic acid).In contrast,the C6C3C6 compounds displayed a notably inhibitory trend in this case.Subsequently,the gene-to-metabolite networks were drawn up by searching for correlations between the expression profiles of 5 gene tags and the accumulation profiles of 36 metabolite peaks.In this study,the comprehensive regulation and induction model of exogenous hormones on phenolic compounds metabolism in C.roseus was described,and the regulation mechanism of phenolic compounds in roseus would be further studied in the future.It has been reported that ethylene and methyl jasmonate are effective inducers for the synthesis of valuable secondary metabolites in C.roseus,but there are few reports on transcriptome of C.roseus induced by ethylene or methyl jasmonate.In this study,a new generation sequencing technique was used to sequence the total RNA extracted from C.roseus.The results showed that phenolic biosynthesis genes in leaves were specifically responsive to ethylene and monoterpene biosynthesis genes in roots were responsive to methyl jasmonate.By comparing RNA sequencing results with NCBI database,37 key genes in the TIAs synthesis pathway of C.roseus were screened,50 candidate ABC transporters protein genes were obtained,and 85 related genes.These genes were detected by real-time fluorescence quantitative PCR,and multivariate data were analyzed.The results showed that tryptamine pathway genes were specifically responsive to methyl jasmonate,while TIAs downstream pathway genes were more sensitive to ethylene.Many ABC family proteins were involved in the transmembrane transport of TIAs.Exogenous hormones can affect the synthesis of alkaloids through the synergistic action of transcription factors and transporters.In vitro cytological tests showed that ethylene and methyl jasmonate had an effect on the anticancer activity and characteristics of TIAs produced by C.roseus.