| According to Chinese Pharmacopoeia(2015 Edition),rhubarb is the dried root and rhizome of Rheum palmatum L.,R.tanguticum Maxim.ex Balf.and R.officinale Baill..Rhubarb has various effects such as diarrhea attack,clearing heat and purging fire,cooling blood and detoxifying,promoting blood circulation and removing blood stasis,etc.Rhubarb has a long history as the mainly-used drug to break blood stasis,activate blood circulation,and break down diarrhea.It has a wide range of clinical applications and is also an important natural drug material.In recent years,with the growth of market demand for rhubarb,wild rhubarb resources are increasingly scarce.Therefore,cultivated rhubarb gradually becomes the main source for clinical use.However,our group found that the seeds used in cultivation of rhubarb were all from wild plants or self-harvesting by farmers in the previous investigation.Because of the lack of excellent varieties,the active ingredients in cultivated rhubarb are lower than those in wild rhubarb generally,and extremely unstable.Therefore,the core germplasm screening of rhubarb is an urgent problem to be solved at present.In this project,rhubarb seeds from 34 different origin areas were collected and cultivated in Lochang County,Longnan City,Gansu Province for 2 years.After that,the phenotypic traits and yield of rhubarb from each origin area were measured.After the harvest of rhubarb,the content of 14 ingredients in 4 categories was determined.The free anthraquin.d.s included aloe emodin,rhein,emodin,chrysophanol,emodin methyl ether,while the binding anthraquin.d.s included aloe emodin,rheinoside,rhubarb glycoside,chrysophan,emodin methyl ether glycoside.Sennoside A and sennoside B were selected representative component of dianthran.d..At last,gallic acid and catechins were the hallmark of tannins.Analyzing and comparing phenotypic traits,yield,and efficacy components content of rhubarb from different producing areas is a way to combine yield and quality so as to build a comprehensive evaluation system.The core germplasm of rhubarb was constructed according to the construction principle and evaluation method of Core Germplasm by combining the yield and quality of rhubarb with the comprehensive use of multiple sampling scales.Screening of excellent rhubarb germplasm was carried out by gray correlation method,which lays a foundation for the conservation of rhubarb germplasm resources and the breeding of good varieties in the later stage.The main results are as follows:(1)Differences of 9 phenotypic characters in Rhubarb.The diversity of phenotypic traits of rhubarb form different producing areas was analyzed,and the results showed that there are differences among them.For the plant height,the Xining rhubarb has a large span indicating the instability.The average plant height of rhubarb from Yahuang,Shuanshui,Qingshui,and Zhuanglang areas is higher than in other areas,and especially the rhubarb from Yahuang is significantly higher than Xining rhubarb.This phenomenon is probably related to the change of longitude.The average leaf width among rhubarbs from different areas has a highly significant difference,and that of Xining rhubarb and Liangzhou rhubarb is smaller than rhubarb from other areas.(2)Content differences of four functional components in Rhubarb from different regions.The analysis of four kinds of efficacy components of rhubarb from different areas showed a great difference.According to the classification of different efficacy components,when choosing rhubarb germplasm with excellent laxative efficacy components,the Qingshui rhubarb and Zhuanglang rhubarb should be preferred,and the species should be Rheum palmatum L..When rhubarb germplasm with brilliant components for clearing away heat and purging fire is needed,the Minxian rhubarb is better,and the species should be R.tanguticum Maxim.ex Balf..When rhubarb germplasm with effective cooling blood detoxification efficacy,Liangzhou rhubarb was the best,and for species-choosing Rheum palmatum L.was the best choice.(3)Construction of rhubarb core collection.The primary core germplasm of rhubarb was constructed by 20%overall sampling proportion and proportional sampling method.The core germplasm of rhubarb containing 21 accessions was finally established by parameter evaluation,principal component analysis and correlation analysis.(4)Screening of different elite rhubarb Germplasm.The excellent rhubarb germplasms were screened by grey correlation analysis base d on yield,traits and pharmacodynamic components.The superior types for diarrhea w ere YH-O-1 germplasm,QT-O-2 germplasm,and SS-P-1 germplasm.The excellent typ es for blood-cooling and detoxification were XN-T-8 germplasm,YH-T-3 germplasm,and YH-T-5 germplasm.The best performance in clearing away heat and purging fire was behaved by XN-T-4 germplasm,SS-P-1 germplasm,and YH-T-3 germplasm.In this paper,the differences and diversities between different regions and differen t Radix Rhei were analyzed and compared from the aspects of phenotypic characters,yield and effective component content.Based on the data of phenotypic characters,yie Id and functional components,the core germplasm was constructed and evaluated by c ore germplasm construction method,which provided convenience for the conservation and utilization of rhubarb germplasm resources.According to the different characteristi cs of rhubarb,excellent agronomic characters,high yield and different efficacy of rhub arb germplasm were screened,which laid the foundation for the breeding and Directio nal Cultivation of rhubarb. |
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