| Quinoa has complete nutritional value,and it has the biological characteristics such as cold resistance,drought resistance,barren resistance and salt and alkali resistance,as a result,it has attracted extensive attention in various countries.Genetic diversity analysis of quinoa germplasm resources is of great significance for introduction collection identification classification and breeding improvement of quinoa.The quinoa germplasm population contains a large number of favorable alleles controlling important traits,Association analysis was conducted to find alleles associated with superior traits in natural germplasm populations.The combination of genetic diversity analysis and association analysis is of great significance for the improvement of quinoa traits,rational utilization of germplasm resources and promotion of molecular marker-assisted breeding of quinoa.In this project,a natural germplasm population composed of 163 quinoa materials and 3 djulis materials was collected as the tested object.The main phenotypic characters and quality characters were investigated and determined,and their genetic variation was analyzed by each trait.65 pairs of simple repeat markers(SSR)primers were used to analyze the genetic diversity of the tested germplasm populations,and the SSR loci associated with superior traits were analyzed.The main research results are as follows:(1)11 phenotypic traits and 3 quality traits of tested quinoa were investigated and determined.The variation coefficients of different traits had great difference and wide range of variation.Plant height,inflorescence length,plant branch,panicle length and stem diameter were significantly positively correlated with plant shape.There was significant positive correlation between leaf length and leaf width.The mature stage was marked significant positive correlation with plant height,and was positively correlated with inflorescence length,plant branch,panicle length,stem diameter and plant shape.There was significant positive correlation between stem color and flower color.The fat content was significantly negatively correlated with plant branch and stem diameter,and was significantly negatively correlated with mature period.Total protein content was significantly positively correlated with stem diameter,negatively correlated with total starch content,positively correlated with plant height,and negatively correlated with leaf width.Principal component analysis showed that the cumulative contribution rate of the first five principal components reached 71.08%.(2)When the genetic distance was 5,all the materials were divided into 4 groups by cluster analysis,and the tested germplasms from different sources were divided into different groups,which indicated that the tested germplasms from the same region had rich genetic diversity.The main characteristics of group Ⅰ were the lowest total protein content and the highest total starch content.The main characteristics group Ⅱ were the lowest total starch content and the highest fat content.The main characteristics group Ⅲ were the Smallest blade,The loosest plant,and the lowest fat content.The main characteristics of group Ⅳ were the larges plant size and the latest average of maturity,and the stem color and flower color were the deepest and the total protein content was the highest.(3)From 156 pairs of SSR primers,65 pairs of primers with high heterozygosity,good repeatability and clear amplification fragments were selected to label the tested material population.The effective number of alleles varied from 1.144 to 9.760,with an average of2.953,the variation of observed heterozygosity ranged from 0.019 to 1.000,with an average value of 0.387,the expected heterozygosity ranged from 0.126 to 0.900,with an average value of 0.588,Shannon’s index ranged from 0.252 to 2.409,with an average of 1.126,The polymorphism information content ranged from 0.121 to 0.889,with an average value of0.524.It proved that the primers selected in this study had high polymorphism.(4)Genetic diversity of tested accessions was analyzed by molecular markers.Cluster analysis divided the materials into three groups.The population structure analysis divided all the materials into two subgroups,which showed a similar tendency to cluster analysis.Principal component analysis showed that the explanation rates of the top three principal components were 58.95%,11.49% and 8.72%,respectively,accounting for 79.17% of the total variation.Principal component 1 divided all the materials into two groups,and accessions of the same origin cluster together on the coordinates.The analysis showed that the genetic relationship of tested accessions was significantly related to its geographical origin,and the tested materials of the same geographical origin had relatively close genetic relationship.(5)A total of 2145 pairs of SSR locus combination were identified by linkage disequilibrium analysis of 65 SSR.The linkage disequilibrium coefficients of all combinations ranged from 0.00 to 0.41,with an average value of 0.05.Under the condition of P<0.01,there were 873 pairs of loci with significant linkage disequilibrium,accounting for41.97% of all loci combinations.Among them,there were 411 pairs of paired loci with D′≥0.5,accounting for 19.76% of all loci combinations,and the level of linkage imbalance was low.The general linear model and mixed linear model were used to analyze the association between 11 phenotypic traits and 3 quality traits of quinoa seed quality and SSR marker loci.Based on the results of the two analyses,the optimal model was selected,and the results showed that 8 SSR markers were closely related to plant height,stem diameter,leaf width,branch number of main stem,leaf length,maturity stage,total protein content and total starch content. |
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