Genetic Diversity And Quality Evaluation Of Thirteen Species Of Dendrobium

Dendrobium Sw.is the largest genus of Orchidaceae.According to the records of the flora of China,there are 74 species and 2 varieties of Dendrobium in China.Although the species of Dendrobium are abundant,the germplasm resources are scarce.Dendrobium is one of the most important rare and endangered plants in china.Because of its medicinal value and ornamental value,the annual demand is far more than its natural growth.Because of the continuous depletion of wild resources,shoddy phenomenon appears on the market.Therefore,it is very important to distinguish the species and quality of Dendrobium.In view of this,the following results were obtained by observing and measuring the morphological indexes,chemical composition and content of the three kinds of Dendrobium varieties and ISSR molecular markers.(1)The morphological indexes of Dendrobium genus were measured by observing and measuring.From the point of view of morphological characteristics,the thirteen species of Dendrobium in this experiment can be classified from three aspects:whole plant morphology,stem morphology and leaf morphology.According to the shape of the whole plant,there were three types of erect,semi erect and horizontal type of the thirteen Dendrobium species.According to the shape of the stem can be divided into two categories:column type(stem top,the lower part of the thickness is roughly the same)and unequal type(mostly for the central stem expansion,the upper and lower part of the fine).According to the leaf morphology can be divided into two categories:the broad leaf type and narrow type.(2)Determination of water content in thirteen species of Dendrobium by drying method.The moisture content was above 50%.Specifically,the drying rate of S5 was 41.76%,the drying rate of S13 was 13.94%.Accordingly,the maximum moisture content of S13 was 86.06%,and the moisture content of S5 was the smallest,which was 58.24%.(3)The polysaccharide content of thirteen varieties of Dendrobium was determined by phenol-sulfuric acid method.The polysaccharide content of all the tested materials was between 0.24%and 0.48%.In particular,the polysaccharide content of S9 was the smallest,0.24%,and the polysaccharide content of S1 was the largest,which was 0.48%.In addition,it can be seen from the experiment,the use of phenol-sulfuric acid method to determine the content of polysaccharides,easy operation,the results intuitive,high sensitivity,good repeatability.(4)The content of coumarin and moanine in thirteen varieties of Dendrobium were determined by high performance liquid chromatography(HPLC).Only S1,S8,S9 containing coumarin,the contents were 1.3%,3.0%,0.4%.Only S5,S9,S11,S12 contain mullin,the content of 1.0%,respectively,4.3%,0.5%,1.7%.In addition,it can be seen from the experiment,high performance liquid chromatography determination of Dendrobium plant coumarin,mullin content,simple operation,the results intuitive,high sensitivity.(5)In ISSR molecular marker experiments,six ISSR primers were screened for ISSR-PCR amplification of thirteen species of Dendrobium.A total of 76 clear and stable bands were detected by ISSR-PCR using thirteen ISSR primers.Among them,there were 75 polymorphic bands with a polymorphic rate of 98.68%Increased length of the band between 200bp-1500bp.The results of the six ISSR primers used in the genus Dendrobium were better.Thirteen Dendrobium plants can be divided into four groups when the genetic similarity coefficient is about 0.64.S5 alone as a group,S7 alone as a group,S6 alone as a group,the other 10 species of Dendrobium species into a group.This shows that Dendrobium exile Schltr.,Dendrobium heterocarpum Lindl.and Dendrobium Sw.and the remaining 10 species of Dendrobium plants far from the genetic relationship.In summary,this study was carried out on thirteen Dendrobium species were described in the form of chemical composition,ISSR molecular markers.From the point of view of the differences,it is not only a reference value for the study of the identification of Dendrobium species,but also the basis for the clinical research of Dendrobium.Due to the scarcity of test materials,the lack of collection of varieties,there are some limitations of the reference.But to a certain extent,it is beneficial to realize the sustainable utilization of medicinal plant resources,and to provide the basis for the evaluation of the quality of Dendrobium and the prospect of artificial cultivation.