Genetic Diversity Analysis Of Olive Introduced From Cheng’du Based On Phenotype And SSR Markers

Olea europaea L.is a world-famous tree species for both oil and fruit.Together with Camellia oleifera,coconut and oil palm,it is known as the world’s four largest woody oil plants.With the continuous expansion of olive cultivation area in China,the demand for yield and quality is also increasing.Breeding high-yield and high-quality olive varieties suitable for cultivation in China has become the need of industry development.The study of genetic diversity is of great significance for the collection,conservation and management of olive germplasm resources and the formulation of efficient breeding strategies.Therefore,in this study,83 olive varieties introduced from Chengdu were used as test materials,and diversity analysis,principal component analysis,cluster analysis and correlation analysis were carried out on the phenotypic quantitative traits,phenotypic quality traits and quality traits of 44 olive varieties.At the same time,34 pairs of SSR primers with high polymorphism were screened for SSR polymorphism analysis,cluster analysis,fingerprint construction and population structure analysis of 83 olive varieties.Correlation analysis was carried out on phenotypic quantitative traits,phenotypic quality traits,quality traits and SSR molecular markers,and the genetic diversity of oleifera germplasm resources introduced in Chengdu was comprehensively assessed,laying the foundation for the selection of oleifera varieties in Chengdu.The main findings are as follows:1.The phenotypic and quality traits of 44 bearing olive varieties were statistically analyzed.The results showed that the coefficient of variation of 14 phenotypic quantitative traits ranged from 6.02-55.04%,and the genetic diversity index was between 1.884-2.137.Among them,the coefficient of variation of pulp rate was the lowest,6.02%,and the maximum single fruit quality was 55.04%;The genetic diversity index of 14 phenotypic quality traits was 0.156-1.691;The variation coefficients of 10 quality traits ranged from6.24-57.14%,and the genetic diversity index ranged from 1.783-2.094.The variation coefficient of eicosenoic acid content was the largest,57.14%,and that of oleic acid content was the smallest,6.24%.2.44 olive varieties were clustered into 5 categories by using 14 phenotypic quantities and 10 quality traits.Using 14 phenotypic quality traits for cluster analysis,it can be divided into four categories.The classification results reflect the differences of phenotypic traits among varieties,indicating that 44 varieties can be completely distinguished by using28 phenotypic traits and 10 quality traits.The correlation results showed that among the 14 phenotypic quantitative traits,the fruit transverse diameter had a very significant positive correlation with the single fruit quality,and the correlation coefficient was 0.955;There was a very significant positive correlation between linoleic acid and oleic acid in 10 quality traits,which was 0.864;Mantel test was used to analyze the correlation between phenotypic quantity and quality traits and phenotypic quality traits.The results showed that the R value was 0.14 and the p value was 0.07.The 24 phenotypic quantitative and quality traits of 44 olive germplasm were divided into 8 principal component factors by principal component analysis,of which 3 were yield factors and 5 were fatty acid factors.Through the comprehensive evaluation of phenotype and quality traits,it was concluded that the suitable varieties for Chengdu planting were Gordal,Picholine Languedoc,Picudo and EZ-8.3.A total of 303 pairs of alleles were amplified by 34 pairs of SSR primers from 83 olive varieties,with an average of 8.91 polymorphic sites amplified per pair of primers.SSR marker polymorphism analysis showed that the polymorphism information content of34 pairs of primers was 0.5150-0.8490,the number of effective alleles was 2.192-7.356;the Shannon’s index was 1.094-2.171;the observed heterozygosity was between 0.036 and1.000;the expected heterozygosity was 0.544-0.864.The results indicated that the 34 pairs of SSR primers had high polymorphisms,which could provide rich genetic diversity information,and also indicated that the olive varieties introduced in Chengdu had high genetic diversity.4.Cluster analysis of 34 pairs of SSR genotypes by NJ method,83 olive varieties can be divided into three categories;Among them,5 pairs of SSR primers can completely distinguish 83 varieties,construct the specific fingerprints of 83 varieties,and convert the fingerprints of 44 tested varieties into fingerprint two-dimensional code;Compared with olive germplasm resource bank,14 varieties were identified,of which 11 varieties had the same genotypes as those in the germplasm resource bank,and the other three varieties with great differences were misnamed varieties;The results of population structure analysis showed that 83 olive varieties could be divided into two groups.There was gene exchange among olive varieties from different origin,and there was genetic differentiation among olive varieties from different countries.5.Through Mantel test,the correlation between SSR markers and phenotypic quality traits,phenotypic quantity and quality traits in olive is weak(r =-0.096,-0.015),but SSR molecular markers can completely distinguish varieties with similar phenotypes.Therefore,the combination of molecular markers and phenotypic traits can effectively improve the efficiency of olive Germplasm identification.