| Ginkgo biloba is a deciduous tree of Ginkgo biloba.It is a unique multi-purpose economic forest in China.It is called "living fossil" and is one of the key protected plants in China.Ginkgolide compound is an important active ingredient in Ginkgo biloba leaves.It has extremely high medicinal value and has good curative effect in preventing and treating cardiovascular and cerebrovascular diseases.Selenium is one of the elements required for plant growth.It stimulates plant growth and development,improves crop yield and quality,and has a certain role in plant metabolism bio-oxidation and resistance to environmental stress.Moreover,selenium can interact with other elements in plants,there by affecting the physiological functions of plants.In this experiment,three-year-old Ginkgo biloba leaf houseplants were used as test materials to apply Na2Se03 to ginkgo seedlings.The selenium application method was foliar spraying and root watering.Some physiological indexes were also determined to study the effects of inorganic selenium on the growth and physiological aspects of Ginkgo biloba seedlings.Furthermore,the effects of selenium on the content of terpenoids in Ginkgo biloba L.at different time points were analyzed by different selenium application methods.Through the combined analysis of transcriptome and metabolome,the differences of differential genes and metabolites in Ginkgo biloba leaves after exogenous sodium selenite treatment were analyzed.The six key genes DXS,DXR,MECT,MECPs and HMGR synthesized by ginkgo biloba compounds were analyzed.The expression analysis of MVD further clarified the mechanism of sodium selenite regulating the synthesis of steroids through the changes of scorpion-related genes.The results show that different exogenous inorganic selenium application methods have certain effects on the physiological growth of Ginkgo seedlings.The trends of soluble sugar and soluble protein in Ginkgo biloba leaves over time were tested by different treatment methods.The results showed that the selenium application on the leaves increased the soluble sugar content of Ginkgo biloba leaves,and the sugar content began to fall with time.The e ffect of selenium on the soluble sugar of Ginkgo biloba leaves was not obvious,indicating that the ginkgo leaves were inorganic.The physiological response of selenium is greater than that of the root.On the basis ofprevious studies,the experimental group with the largest difference in terpenoid content was selected:the concentration of leaves was 20 mg/mL(group A)and the concentration of root application was 20 mg/pot(group B)for transcriptome sequencing,and the sequencing results were submitted.Nr,Nt,Pfam,KOG/COG,Swiss-prot,KEGG,GO seven databases,a total of 142,834 unigenes,with an average length of 656 bp.The number of Unigenes annotated in the KEGG and KEG databases is less than 25,000,the number of annotations in other databases is more than 40,000,and the number of annotations in the NR NT,and SwissPort databases is even more than 50,000.The KOG data alignment showed that 18,671 unigenes successfully annotated to KOG were distributed in 26 functional categories,including the most post-translational modifications,protein folding and molecular chaperones(14.97%),followed by translation,ribosome structures and organisms.Synthesis(12.4%),secondary metabolite synthesis,transport and metabolism(10.7%).Differential gene analysis There were 4653 differential genes in the leaf application group and the control group.There were 2546 differential genes in the root application group and the control group,while there were only 394 differentially expressed genes in the root application compared with the leaf application.The KEGG enrichment analysis of differentially expressed genes showed that the differential genes of the leaf application group and the control group were mainly Phenylpropanoid biosynthesis,plant hormone signal transduction,amino acid and nucleotide sugar.Amino sugar and nucleotide sugar metabolism and starch and sucrose metabolism,while there was no significant enrichment between the treatment groups.Among them the pathways related to the synthesis of terpenoids are mainly steroid skeleton biosynthesis,biosynthesis of sesquiterpenoids and triterpenoids,monoterpenoid biosynthesis,diterpenoid biosynthesis,and ubiquinone and other steroidal organisms.synthesis.A total of 991 metabolites,including known and unknown metabolites,were detected in the metabolome test,of which only 9 terpenoids were detected,namely gentian buckwheat,zeaxanthin plant cedarane C,zeaxanthin,and yam Saponins,caffeol,alfalfa,rice diterpenoids and plant cedar.Through the screening of differential metabolites,there were 315 differential metabolites between the control group and the leaf application group.There were 324 differential metabolites between the control group and the root application group,while there were only 154 differential metabolites between the treatment groups.Through the KEGG pathway enrichment analysis,only the diterpenoid biosynthesis pathway was found,and the related poor metabolites were only gibberellin 3 and gibberellin 7.Six candidate genes were screened by analyzing the KEGG pathway involved in the synthesis of terpenoids.qRT-PCR was used to verify the selected candidate differential genes.The expression levels of related enzyme genes(DXS,DXR,MECT,MECPs,HMGR MVD)were significantly up-regulated within 5 weeks after treatment with sodium selenite.The expression level will fall back to the control level in the following weeks.This experiment provides comprehensive genetic information and metabolome data for the regulation of physiology and molecular mechanism of exogenous sodium selenite to control the synthesis of Ginkgo biloba,and lays a theoretical foundation for the in-depth study of the molecular regulation mechanism of Ginkgo biloba under selenium treatment conditions. |
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