Genetic diversity and population structure of Cucumis sativus L. by using SSR markers

The genetic variation, marker attributes and population structure was assessed in 104 genotypes of cucumber using 23 SSR primer pairs. The total number of alleles produced was 67 with an average of 2.91 per locus. Allele frequency was in the range of 0.215 to 0.561 with mean value of 0.403, polymorphic information content ranged from 0.158 to 0.495 with the mean of 0.333, marker index ranged from 0.316 to 1.54 with an average value of 0.954 and resolving power ranged from 0.346 to 2.692 with mean of 1.392. The maximum allele frequency was reported with primer SSR65, whereas the maximum value of polymorphic information content and resolving power was found with SSR61 and the maximum value of marker index was reported with SSR60. Jaccard's similarity coefficient ranged from 0.07 to 0.897 with maximum similarity between genotype G40 and G41 and minimum between G16 and G20, and G16 and G100. Clustering and PCA grouped the genotypes in two clusters, and majority of them were found in cluster B. The population structure analysis also showed two major populations, in which 47 genotypes were found in population 1, 39 genotypes in population 2, whereas remaining 18 genotypes were admixtures. The study provides researchers a valuable information for genotype identification, gene mapping, molecular breeding, and future exploration of cucumber germplasm in India and other major cucumber growing countries.