Genetic Diversity of Onion Genotypes using Microsatellite Markers



To study the genetic relationships among Iranian onion landraces and to compare them with those in some foreign cultivars, fifteen microsatellite (SSR) primer pairs were employed. Based upon the results of the obtained band pattern, 12 pairs of SSR primers in 18 onion landraces and five foreign cultivars form a polymorphic and scorable pattern. There were two to six alleles with an average of 3.3 to every gene location. The polymorphic information content was assessed from 0.2 to 0.76 with a mean of 0.52, which was a proof of high heterozygosity in the masses of landraces. Mean genetic diversity within the landraces and within the foreign cultivars varied from 0.12 to 0.28. Analysis of molecular variance based upon square Euclidean distances indicated significant diversity between and within onion landraces and foreign cultivars. However, the amount of variance between varieties (0.42) was less than that between foreign cultivars (0.58). Grouping through Nei similarity coefficient and UPGMA algorithm, separated the onion landraces and foreign cultivars into six groups and an independent genotype. Although grouping on the basis of molecular data was rather compatible with some of the morphological traits, but it did not, as a whole, match the geographical grouping.