Font Size: a A A

Study On The Quality Identification Evaluation And Ecological Factors Of Three Kinds Of Dendrobium Species In Ta-pieh Mountains

Posted on:2021-03-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y D YuanFull Text:PDF
GTID:1363330611995361Subject:Soil and Water Conservation and Desertification Control
Abstract/Summary:PDF Full Text Request
Dendrobium is a larger genus in the Orchidaceae family,with more than 1,500 species worldwide.There are more than 70 species of Dendrobium in China,of which more than 50 are medicinal Dendrobium.Ta-pieh Mountain has unique natural climate conditions,and there are three kinds of Dendrobium,namely Dendrobium huoshanense C.Z.Tanget S.J.Cheng,Dendrobium officinale Kimura et Migo,and Dendrobium moniliforme(L.)Sw.Dendrobium contains active ingredients such as polysaccharides and alkaloids,which have anti-aging,antioxidant and immune regulation effects.At present,the application value of Dendrobium is constantly rising,and the demand is also increasing.However,Dendrobium has low reproductive capacity under natural conditions and high requirements for growth environment,and the wild resources of Dendrobium are on the verge of extinction.The quality of Dendrobium planted in China is uneven and the quality cannot be unified,which leads to the confusion of the currently available Dendrobium medicinal materials.Therefore,this study screened out the three main dendrobium species(D.huoshanense,D.officinale,and D.moniliforme)in Ta-pieh Mountains,compared and identified the three Dendrobium species by methods such as character identification and microstructure comparison.By analyzing the biological characteristics,medicinal ingredients of three kinds of Dendrobium,and effectively discovering and identifying genes encoding secondary metabolite biosynthetic enzymes and genes related to their metabolic regulation,and comprehensively evaluating the quality characteristics and quality-forming molecules of the three Dendrobium mechanism.Furthermore,the growth environment of three kinds of Dendrobium in Ta-pieh Mountains areas in different growth modes was monitored to explore the correlation between ecological factors and their medicinal ingredients.The main research conclusions are as follows:(1)In this study,the results showed that under ordinary light microscope and fluorescence microscope,different tissues of different types of Dendrobium show different morphologies.At the same time,the stems of Dendrobium with different growth years were collected as materials to determine their polysaccharides and total alkaloids.It can be seen from the results that the polysaccharide content of the three kinds of Dendrobium in different growth years is between 249.31mg·g-1 and 547.66 mg·g-1,among which the three-year-old D.huoshanense has the highest polysaccharide content.The total alkaloid content is between 0.21 mg·g-1-0.54 mg·g-1,and the highest content is also three-years-old D.huoshanense.We measured the amino acid content of these three Dendrobium in different growth years,and we can see that these three Dendrobium contain seven amino acids required by the human body.A safety evaluation of the basic trace elements of Dendrobium was conducted.The results showed that the dosage of 12 g·d-1 Dendrobium prescribed in the Chinese Pharmacopoeia met the recommended daily intake of trace elements recommended by the US Food and Drug Administration and would not cause trace element poisoning.(2)In order to explore the molecular mechanism of different active components of different Dendrobium and different tissues of the same kind of Dendrobium,we selected the roots,stems and leaves of D.huoshanense,D.officinale and D.moniliforme for transcriptome sequencing and pathway mining.By comparison with the CAZy database,1407 unigenes related to polysaccharide activity were identified.In the family of glycosyltransferase genes(GTs),315 differentially expressed genes(DEGs)were identified.In Dh_L vs.Dh_S and Dh_R vs.Dh_L,124 and 58 DEGs were related to the biosynthesis of D.huoshanense alkaloids.In Dh_R vs.Dh_S,62 DEGs related to D.huoshanense terpenoid pathway were identified.Using fluorescence quantitative PCR,five key enzyme genes in the terpenoid pathway were identified and their expression patterns in different tissues were verified.A total of 24,927 genes were obtained by transcriptome sequencing of the roots,stems and leaves of D.officinale.We compared all genes to the pathways in the KEGG database to determine the polysaccharides and secondary metabolic pathways that these genes may be involved in.Key enzyme genes related to flavonoids were also identified,and their expression patterns in different tissues were further analyzed using real-time fluorescent quantitative PCR.By identifying the CHS gene family of D.officinale,five CHS genes were obtained,and the structure and evolutionary relationship of these genes were further analyzed.In D.moniliforme,562,580unigenes were generated by transcriptome sequencing.Based on the transcriptome-based gene annotation,through comparison with the CAZy database,1,204 unigenes related to polysaccharide activity were identified,including 417 glycosyltransferase genes(GTs),780 glycoside hydrolase genes(GHs),and 19 glycoesterase genes(CEs),75 carbohydrate-binding modules(CBMs)and 44polysaccharide lyase genes(PLs).In the cellulose synthase family,21 differentially expressed genes related to polysaccharides were found.Subsequently,the tissue-specific expression patterns of genes involved in the polysaccharide pathway were studied,providing a basis for understanding the biosynthesis and regulation of D.moniliforme polysaccharides at the molecular level.By real-time fluorescence quantitative PCR,two key enzyme gene families(Susy and SPS)involved in the polysaccharide pathway were identified,and their expression patterns in different tissues were further analyzed.(3)We used weighted gene co-expression network analysis(WGCNA)and gene expression profiles of active ingredients to identify modules and genes that may be relevant to specific species and tissues.RNA was extracted from three Dendrobium plants and three tissues,a high-quality transcriptome database was established,and 8,056 homologous genes were identified for WGCNA analysis.Based on the significant changes in gene expression,a co-expression network was constructed and 19 gene modules were revealed.Because polysaccharides and alkaloids are the main medicinal components of Dendrobium,so we focus on the synthesis genes and metabolic pathways of these metabolites.We screened out four functional modules related to polysaccharide,alkaloid regulation and biosynthesis functional research.These results improve our understanding of the biosynthesis of this important medicinal plant active ingredient and will help guide more in-depth research.(4)In this study,the main components(polysaccharides,total alkaloids,total flavonoids)of D.officinale were determined under three different growth modes:greenhouse,bionic and wild.It was found that among the three growth modes,the wild growth mode of medicine is the highest value.After a series of statistical analysis,there are eight ecological factors that are considered to be the key factors affecting the main medicinal components in the cultivation process of D.officinale,they are maximum relative humidity,minimum relative humidity,maximum temperature,sunshine hours,substrate pH values,total nitrogen in the substrate,total phosphorus in the substrate,and available phosphorus in the substrate,these findings provide innovative ideas for exploring the complex relationship between ecological factors and medicinal value in artificial cultivation.
Keywords/Search Tags:Dendrobium, identification evaluation, medicinal component, transcriptome, ecological factors
PDF Full Text Request
Related items