Evaluation Of Drought Tolerance And SSR Correlation Analysis Of Soybean Core Germplasm Resources During Germination

Soybean（Glycine max（L.）Merr.）is rich in protein,fat,isoflavones,phospholipids and dietary fiber,and is an important food and industrial raw material.Shanxi Province is one of the important undertakings of soybean production in China,located in the middle reaches of the Yellow River.It has a cultivated area of 4.804 million square hectares,of which 80% belong to the dry land.The annual precipitation in Shanxi Province is less than 400 mm,there are many strong winds in spring,soil moisture loss is fast,the precipitation is concentrated in summer,prone to spring drought.Drought is one of the main reasons limiting soybean production in Shanxi Province.Cultivating drought-resistant varieties is the most fundamental solution to drought,and germplasm resources are the material basis for the cultivation of new varieties.Cultivating new drought-tolerant varieties with drought-tolerant germplasm resources is an effective measure to solve the dilemma of soybean production in Shanxi Province.Shanxi Province is long and narrow from north to south,with a difference of 4 latitudes.There are mountains,basins,and hills in the territory.The geographical environment of continuous drought in Shanxi Province has bred abundant drought-resistant germplasm resources.This study analyzed the phenotypic diversity of 1999 soybean germplasm resources in 11 cities,103 counties and districts in Shanxi Province.The local core germplasm of Shanxi was constructed.Then the drought tolerance at the bud stage was evaluated,and the SSR markers were used to scan to find the excellent allelic variants related to drought tolerance.The main results are as follows:1.Shanxi soybean genetic resources are rich and diverse.Through the analysis of the source of local soybean in Shanxi Province,it was found that the genetic resources of local soybean were mainly distributed in Xinzhou（314）,Changzhi（300）,Linfen（277）,Jinzhong（266）and Datong（221）,the resources are 1378,accounting for 68.93% of the total resources.The genetic diversity of soybean germplasm resources was rich in Shanxi province,and the diversity difference between cities and regions was small,with the average diversity index ranging from 2.0261（Yangquan）to 2.5609（Jinzhong）.2.Construction of core germplasm of Shanxi local soybean.213 core collections of original collections were constructed,accounting for 10.66% of the original collections,through clustering and random sampling of 1999 historical data of Shanxi local varieties.T-test and F test of the 19 phenotypic traits showed that there were no significant differences between the core germplasm and the original germplasm,indicating that the core germplasm retained the genetic variation of the original germplasm.The range coincidence rate between the core germplasm and the original germplasm was 136.29%,the percentage difference between mean and variance was 0,and the change rate of variation coefficient was 106.443%,which indicated that the core germplasm could well represent the original germplasm.3.Drought tolerance identification of core germplasm at germination period.Three varieties with different drought tolerance,TN4-94（drought-resistant type）,Meng8206（intermediate type）and Jindou 19（sensitive type）,were used to set CK and five treatment concentrations of 16%,18%,20%,22% and 24% for concentration screening.The results showed that 20%PEG-6000 was the suitable concentration for drought tolerance in germination.Using 20%PEG-6000 to identify the drought tolerance of the core germplasm in germination,the results showed that 2 germplasm were drought-tolerant（level 1）,27 germplasm were drought-tolerant（level 2）,120 germplasm were intermediate（level 3）,116 germplasm were sensitive（level 4）,and 14 germplasm were sensitive（level 5）.The two tolerant germplasm（Grade 1）were from local varieties,respectively from Linfen and Xinzhou.Among the drought-tolerant germplasm,24 germplasm were from local varieties,and 3 germplasm were developed varieties.4.Elite allele analysis.（1）Analyze the identification materials of bud stage by SSR molecular markers,and use the software Structure 2.3.4 to divide 279 materials into 2 subgroups.There are 169 materials in subgroup I,including all bred varieties（59）and 110 local varieties;There are 110 accessions in subgroup II,all of which are local varieties.Subgroup Ⅰ Linfen has the most local varieties,and subgroup Ⅱ Xinzhou has the most materials.The number of species prime of the sensitive type（Level 4）in subgroup I was 79,and that of the sensitive type（Level 5）in subgroup II was 106.A total of 177 alleles were collected from 279 materials,with an average of 4.317 alleles per marker and an average of 2.357 effective alleles.The number of satt354 alleles was up to 9,and the number of effective alleles was 3.4576.The maximum number of effective alleles of Satt441 is 4.7288,and the number of alleles is 8.The PIC of satt441 is the largest at 0.78852.（2）GLM model of Tassel 2.1 was used to make association analysis of the identified traits using population structure Q value as covariable.A total of 33 markers related to phenotypic traits were found at the significant level of P<0.05.The explanational rate of phenotypic variation was1.67%-10.23%,with an average of 4.73%.At the extremely significant level of P<0.01,a total of 16 markers related to phenotypic traits were found,and the phenotypic variation explanation rate was 2.46% 10.23%,with an average of 6.16%.At the 0.05 significant level,5 SSR markers were found directly and significantly related to drought tolerance at bud stage,Sat₁72、Satt337、Satt237、Satt271 and Sat₄19;The maximum positive of Sat₁72（285）was 0.0769,The typical materials were big red beans from Changzhi.Satt237（296）had the maximum negative of-0.1044,typical materials such as black bean from Linfen.Among them,Sat₁72,Satt237,Satt271 three sites are still significantly related to the average total membership function at a significant level of 0.01.In addition,Sat₁60,Sat₂41,Sat₂96,Sat₃58,Satt094,and Satt130 are related to individual traits.