| Erigeron breviscapus(Vant.)Hand-Mazz.,also known as Erigeron breviscapus,is a perennial herb belonging to the genus Erigeron in the family Compositae.It is mainly distributed in Yunnan,Sichuan and other western and southwestern regions of China at an altitude of 1200-3500 m.Flavonoids,flavonoid glycosides,pyranones,sesquiterpenes,caffeoyl and other components have been identified in Erigeron breviscapus.Flavonoids,flavonoid glycosides and caffeic acid esters are the main active compounds,which are widely used in the treatment of cerebrovascular diseases.Methyl jasmonate(Me Ja)is a new type of plant growth regulator,which plays an important role in plant resistance to adversity and stress.When plants are subjected to biotic and abiotic stresses,Me Ja can respond to external signals and initiate stress-resistant genes,thereby enhancing plant stress resistance and regulating plant growth and development and secondary metabolism.In this paper,Erigeron breviscapus was used as the research object.The soil culture method was used to spray different concentrations of methyl jasmonate on Erigeron breviscapus.Through the changes of plant morphology and flavonoid content of secondary metabolites,the most suitable conditions for methyl jasmonate to alleviate drought were obtained.On this basis,chlorophyll fluorescence analysis and transcriptome sequencing of roots and leaves of Erigeron breviscapus under methyl jasmonate treatment were carried out to reveal the changes of related genes under methyl jasmonate treatment at the omics level,hoping to elucidate the mechanism of methyl jasmonate on the improvement of drought resistance of Erigeron breviscapus and the increase of flavonoids in Erigeron breviscapus under drought stress,and analyze the correlation between genes involved in methyl jasmonate alleviating drought and regulating flavonoids content.The main research results are as follows :1.Three concentrations(0.5mmol / L,1mmol / L,1.5mmol / L)of methyl jasmonate were set to treat Erigeron breviscapus,and 1mmol / L methyl jasmonate solution spraying could significantly alleviate the drought stress of Erigeron breviscapus.The physiological indexes of leaf water content,flavonoid content,soil water content,stomatal size and chlorophyll content were detected.Compared with drought and normal control plants,the leaf water content and chlorophyll content of Erigeron breviscapus plants sprayed with 1mmol / L methyl jasmonate increased;the content of flavonoids in roots and leaves increased,soil water content decreased and stomata closed,indicating that exogenous methyl jasmonate treatment could effectively alleviate the damage of drought stress on Erigeron breviscapus and increase the content of flavonoids.2.Chlorophyll fluorescence imager was used to determine the explants of different treatments.The changes of FO,Fv / Fm,NPQ and Qp of Erigeron breviscapus under methyl jasmonate addition,drought and normal conditions were analyzed.The results showed that the FO value in the drought group was the highest.With the prolongation of treatment time,FO,NPQ and Qp increased,and Fv / Fm decreased.The FO,NPQ and Qp of the methyl jasmonate treatment group decreased,and Fv / Fm increased.It shows that drought stress can obviously cause the change of chlorophyll fluorescence parameters,its photosynthetic efficiency decreases,and heat dissipation increases obviously.Methyl jasmonate treatment,especially 1mmol / L methyl jasmonate treatment,can alleviate the changes of chlorophyll fluorescence parameters.3.The results of transcriptome analysis of materials treated under different conditions showed that :Among the differentially expressed genes in the leaves of the normal group and the drought group,1521 genes were up-regulated and 3372 genes were down-regulated.Among the differentially expressed genes in the roots,482 genes were up-regulated and 716 genes were down-regulated.Among the differentially expressed genes in the leaves of the drought group and the methyl jasmonate group,1862 genes were up-regulated and 632 genes were down-regulated.Among the differentially expressed genes in the roots,625 genes were up-regulated and 306 genes were down-regulated.In the normal group and the methyl jasmonate group,there were 1039 up-regulated genes and 1596 down-regulated genes in the differentially expressed genes of leaves,794 up-regulated genes and 826 down-regulated genes in the differentially expressed genes of roots.The results of GO functional analysis showed that the differential genes of leaves were mainly enriched in cell membrane,membrane composition,inner membrane composition,catalytic activity,hydrolase activity,cell process,intracellular organelles,organelles and biosynthesis process.The differential genes of roots were mainly enriched in cell membrane,membrane composition,membrane composition,inner membrane composition,catalytic activity,hydrolase activity and transferase activity.The results of KEGG functional analysis showed that :Differential genes in leaves were mainly enriched in amino acid biosynthesis,starch and sucrose metabolism,carbon metabolism,plant hormone signal transduction,phenylpropanoid biosynthesis,ribosome,and cell cycle.The differential genes in roots were mainly enriched in cell cycle,DNA replication,meiosis-yeast,cell cycle-yeast,phenylpropanoid biosynthesis,carbon metabolism,amino acid biosynthesis,starch and sucrose metabolism.4.By analyzing the differentially expressed genes in the pathways related to phenylpropanoid biosynthesis,plant hormone signal transduction and flavonoid biosynthesis in the transcriptome,it was found that plants were involved in the regulation of breviscapus stress in two aspects under methyl jasmonate treatment :First,under the regulation of methyl jasmonate,some genes related to the synthesis of flavonoids are basically regulated to promote the formation of flavonoids in plants.Second,the genes that alleviate drought under methyl jasmonate treatment are up-regulated.The genes related to drought relief and improvement of flavonoids are : PAL(phenylalanine ammonia lyase),COMT(caffeic acid 3-O-methyltransferase)and 4CL(trans-cinnamic acid 4-monooxygenase),CHS(chalcone synthase),ANS(anthocyanin synthase)These genes can form flavonoids.The genes related to drought and methyl jasmonate are K13464 JAZ(jasmonate ZIM domain protein),K14506 JAR1＿4＿6(jasmonic acid-amino synthetase),K14432 ABF(ABA response element binding factor).To sum up :Methyl jasmonate can alleviate the drought stress of Erigeron breviscapus and increase the content of flavonoids.The research conclusions not only provide a basis for studying the regulation of secondary metabolism,the regulation mechanism of drought stress and the correlation between them,but also provide basic data for further exploring the regulation mechanism of jasmonic acid hormones on the material metabolism and active ingredient synthesis of Erigeron breviscapus. |
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