| Eurya muriata Dunn is a dioecious evergreen shrub or small arbor,belong to Eurya of Pentacene.It has high medicinal value because it is rich in active components such as terpenoids,alcohol and flavonoids.It is also an excellent nectar source plant in southern China.However,its nectar secretion is greatly affected by climate,the amount of nectar secretion is unstable,and the metabolic mechanism is still unclear.Methyl jasmonate(Me JA)controls plant central processes and plays an important role in plant growth and development,flower development and opening,and nectar secretion.In order to clarify the effect of Me JA on plant metabolism,this article used E.muricata as experimental material.After Me JA spray treatment in its nectar period,a series of changes in E.muricata response to Me JA were studied based on metabolomics system.Solid phase microextraction coupled with gas chromatography mass spectrometry(SPME-GC-MS)was used to detect volatile organic compounds(VOCs)in E.muricata flower and conduct qualitative and quantitative analysis.High performance liquid chromatography evaporative light scattering(HPLC-ELSD)was used to qualitatively and quantitatively analyze the sugars in E.muricata nectar.Non-targeted metabolomics detection of primary metabolites and secondary metabolites of E.muricata was performed by means of GC-MS and ultra-high performance liquid chromatographytime-of-flight mass spectrometry(UPLC-Q-TOF-MS).The main results are as follows:1.Based on SPME-GC-MS,27 and 31 VOCs were identified from female and male flowers of E.muricata,respectively.The terpenes dominated by basil accounted for 79.49%-87.18% of the total volatiles.The results of principal component analysis(PCA),orthogonal partial least squares discriminant analysis(OPLS-DA)and volcano map showed that Me JA treatment caused significant changes in VOCs of female and male flowers.The content of 8 VOCs in female flowers increased,including 4-hexen-1-ol,5-methyl-2-(1-methylethenyl)-,acetate,1,3,7-octatriene,2,7-dimethyl-,translinalool oxide,camphor,hydroxylinalool,hexadecane,caryophyllene and α-farnesene;One is reduced,which is α-phellandrene;Six VOCs in male flowers were upregulated,including piperitone,2-isopropenyl-5-methylphenol,trans-linalool oxide,terpinen-4-ol,1,3-cyclohexadiene,1-methyl-4-(1-methylethyl)-and hydroxylinalool;Four types of downregulation are phenol,2-ethyl-4-methyl-,β-cymene,camphor,and α-farnesene.2.HPLC-ELSD detected fructose,glucose,and sucrose in the nectar of E.muricata The content of three kinds of sugars were 1.27 ± 0.97 μg/piece,0.92 ± 0.19μg/piece and 15.01 ± 8.49 μg/piece in the nectar of female flowers and 7.24 ± 1.77μg/piece,7.21 ± 0.02 μg/piece and 67.65 ± 15.19 μg/piece in the nectar of male flowers,respectively.Sucrose accounted for 82.4%-87.3% of the total amount of three kinds of sugars.After Me JA treatment,the contents of fructose,glucose,and sucrose in female flower nectar were increased by 2.52 ± 0.81 μg/piece,2.15 ± 0.86 μg/piece and 35.64± 4.94 μg/piece,respectively.The content of fructose,glucose,and sucrose in male flower nectar increased to 12.04 ± 6.28 μg/piece,10.94 ± 5.30 μg/piece and 72.39 ±19.30 μg/piece,respectively.3.Silylation derivatization combined with GC-MS identified 30 and 38 primary metabolites in E.muricata flowers and leaves,respectively.Both PCA and OPLS-DA showed that there was no significant change in the types of primary metabolites of E.muricata flowers and leaves after Me JA treatment,but the relative content changed significantly.5 and 3 different substances appeared in female and male flowers,respectively.KEGG analysis showed that these different substances mainly involved six metabolic pathways,including galactose metabolism,butyrate metabolism,and glyceride metabolism.There were 14 and 8 different substances in female and male leaves,respectively,mainly involving 19 metabolic pathways,of which 8 were significantly enriched,including butyrate metabolism,citrate cycle,and arginine biosynthesis.4.Based on UPLC-Q-TOF-MS,96 compounds were identified from E.muricata flowers and 84 compounds were identified from leaves.Quantitative analysis of phenolic compounds indicates that the high content of phenolic compounds in flowers were gallic acid,catechin,ellagic acid,and luteolin.After spraying Me JA,the total amount of phenolic compounds in female and male flowers increased by 3.16 μg/g DW and 5.32 μg/g DW,respectively;The high content of phenolic compounds in leaves are luteolin and gallic acid.After spraying Me JA,the total amount of phenolic compounds in female and male leaves increased by 6.80 μg/g DW and 4.61 μg/g DW,respectively.The heatmap results showed that Me JA treatment did not cause significant changes in the types of metabolites in the flowers and leaves of E.muricata,but had varying degrees of impact on the content,which was conducive to the accumulation of metabolites in E.muricata.Through KEGG,the identified metabolites of E.muricata flower were co-enriched into 16 metabolic pathways such as flavonoid and flavonol biosynthesis,flavonoid biosynthesis and purine metabolism,while the leaves were coenriched into 20 metabolic pathways such as flavonoid and flavonol biosynthesis,flavonoid biosynthesis and phenylalanine metabolism.This study comprehensively revealed the effects of spraying Me JA on the main metabolites in the nectar,flowers and leaves of E.muricata from a metabonomic perspective.Studies show that spraying Me JA improves the content of sugars in E.muricata nectar,and increases the content of sugars,organic acids and phenolic compounds in flowers and leaves,indicating that spraying Me JA promotes the accumulation of metabolites in the nectar,flowers and leaves of E.muricata.This study provide scientific basis for the development and utilization of Eurya resources. |
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