Study On Drought Resistance And Diversity Of Astragali Radix Germplasm Resources

There is a lack of germplasm resources of wild Astragalus membranaceus(Fisch.)Bge.var.rmongholicus(Bge.)Hsisao or A.membranaceus(Fisch.)Bge in China,and the artificial breeding is seriously lagging behind.Variety resources have become the main bottleneck restricting the development of Astragali Radix industry.It is very important for establishing of high yield and strong resistance Astragali Radix germplasm,strengthening the breeding of A.membranaceus var.mongholicus and A.membranaceus,and promoting the development and utilization of Astragali Radix to investigate and collect germplasm resources and to study on drought resistance and diversity of germplasm resources of Astragali Radix.The 12 provenance seeds of A.membranaceus var.mongholicus and A.wmembranaceus were collected in this study.Based on seed quality,under conditions of polyethylene glycol drought stress and water control pot-cultured,the drought resistance of Astragali Radix germplasm resources was comprehensively evaluated by analysis of morphological,physiological and biochemical indexes in three critical growth periods(seed germination,seedling and reviving)with the methods of comprehensive drought resistance coefficient analysis,weight subordinate function value,principal component analysis,cluster analysis.Moreover,the diversity of Astragali Radix germplasm resources was studied systematically from the aspects of agronomic traits,molecular markers and chemical composition characteristics based on the field experiment and laboratory analysis.The main results are as follows:1.There is a great difference for single seed quality index among the provenances.There was a significant negative correlation between seed vigor and latitude and longitude,and the water absorption rate of the seeds is positively correlated with the annual precipitation,and germination energy and germination rate are positively correlated with annual rainfall and annual average temperature.The order of comprehensive evaluation index weight subordinative function vaule D from big to small is WD(Wendeng),HY(Hunyuan),LQ1(Gansu Qi No.1),WC(Wuchuan),TY(Taiyuan),LQ2(Gansu Qi No.2),YL(Yulin),YY(Yiyuan),Longxi(LX),GY(Guyang),CF(Chifeng),ALH(Alihe).2.The indexes of drought resistance identification screened in seed germination period are germination index,germination rate,germination energy,radicle length,seedling dry weight.The 12 A.membranaceus var.mongholicus and A.membranaceus provenances can be clustered into 2 groups TY,GY,LX,HY and LQ1,WC,YL,CF,LQ2,ALH,YY,WD.The comprehensive drought resistance coefficient and weight subordinative function value D of LQ1,WC,LQ2,YL,GY are ranked in the front.3.The drought resistance identification indexes screened in seedling period are plant height,root dry weight,root/shoot ratio,SOD enzyme activity,transpiration rate and net photosynthetic rate.The 12 provenances are clustered into three groups,HY,GY,WC,LQ1,CF as drought resistant types,YL,TY,ALH,LX,LQ2 as medium drought resistance types,WD and YY as the drought sensitive types.4.The drought stress delay reviving stage of A.membranaceus var.mongholicus and A.membranaceus and inhibits the ability and vitality of seedling establishment.The indexes of drought resistance identification are root diameter,root/shoot ratio,nodule number,the dry weight,relative conductivity.The 12 provenances are clustered into three groups,WC,LQ2,ALH,WD with poor drought resistance,GY and HY with strong drought resistance,YL,YY,LX as a complex type.By the comprehensive evaluation of D value,YL,LX,GY,HY are stronger in drought resistance.5.Agronomic traits of Astragali Radix germplasm resources with abundant variation are mainly influenced by annual average temperature and annual rainfall the of provenance region.The agronomic traits show a high genetic diversity,and the main indexes of agronomic traits screened by principal component analysis are the root diameter,stem diameter,root volume,the dry weight and the length of the main root.The agronomic traits are clustered into three groups:WD and YY,ALH,and others.The comprehensive evaluation of D value show that WD,YY,HY,WC are ranked in the front.6.By HPLC fingerprint and clustering analysis,The 12 provenances are divided into four kinds of chemical types:ALH,LX,LQ2,and others.There is significant diference for the content of 5 kinds of active components calycosin-7-glucoside,ononin,calycosin,formononetin,astragaloside A among Astragali Radix.There is a significant positive correlation between calycosin-7-glucoside and most agronomic traits,and linear correlation with root fresh weight.According to active components,all provenances are clustered into three groups:ALH;GY,WD,LQ2and others.ALH show a unique chemical composition and activity characteristics.7.By the analysis of ISSR molecular markers,the genetic diversity and genetic variation are very different for every provenance,and the variation mainly comes from inside the provenance.According to the molecular fingerprint,12 provenances are clustered into three main groups:YY and WD,WC,and others.WC provenance with a unique genetic background is a focus of the next selection of germplasm resources.The analysis of genetic markers,chemical components,active components and agronomic traits show that HY,YL,CF,TY,LQ,are clustered into a group with very close genetic relationship.The genetic relationship in genetic resources has been clarified and the evaluation system has been established after studying drought resistance and diversity of germplasm resources of Astragali Radix,which laid a sound foundation,offered theory support and practice direction for breed selection of drought resisting,high yielding and activity components.