Evaluation of Genetic Diversity of Rapeseed (Brassica napus L.) Cultivars Using SRAP Markers

Rapeseed is cultivated as a valuable oilseed plant throughout the world. The rapeseed oil contains significant amounts of unsaturated fatty acids. A total number of twenty-five cultivars of (winter/spring) rapeseed were grown in greenhouse conditions. In order to investigate genetic diversity, genomic DNA was extracted from the leaves and polymerase chain reaction was performed using 12 pairs of SRAP primers. Based on the results, 96 polymorphic bands were detected, in which the EM10-ME10 primer pairs with 14 bands and the EM1-ME14 and EM10-Me1 primer pairs with 4 bands had produced the maximum and minimum number of polymorphic bands, respectively. The Polymorphic Information Content (PIC) index varied from 0.25 to 0.499 and the genetic diversity based on Nei's index was 0.18 to 0.33. The cluster analysis using UPGMA method, with 95% accuracy of the grouping, was introduced as more appropriate than the other clustering methods. This method divided the studied cultivars into five distinct groups. The most genetic distance was recorded between Hydromel and Elvis, Zarfam, Artist and Okapi cultivars, and the lowest was shown between Artist and Okapi cultivars. Based on the results of principal coordinate analysis, the first and second components explained 83.66% of the variation, which represents the improper distribution of the SRAP markers on the whole genome. Overall, this study demonstrated high genetic diversity among cultivated rapeseed cultivars, which may be attributed to their high genetic background and environmental effects.