Detection of genetic diversity using RAPD-PCR and sugar analysis in watermelon [Citrullus lanantus (Thunb.) Mansf.] germplasm

RAPD (random amplified polymorphic DNA) markers generated by 15 arbitrary decamers were used to determine the frequency of DNA polymorphism in 39 watermelon [Citrullus lanantus (Thunb.) Mansf.] germplasms. Of the 15 primers tested, all except 1 (primer 275) directed the amplification of polymorphic products. A total of 162 amplification products were generated across all 39 genotypes. Among the 162 fragments, 35 (21%) appeared to be reliable polymorphic markers. The mean value by marker difference in this comparison was 0.24, and the highest, 0.69. Eight RAPD markers could be utilized in the unique variety discrimination 8 watermelon genotypes. From the phenograms constructed by UPGMA based on the comparison of RAPD markers, four clusters were resolved. Each group was also characterized and identified with morphological and genetic characteristics for each genotype. The free sugars of the edible parts of watermelons were analyzed by HPLC (high- performance liquid chromatography). Results from the phylogenetic analysis of band sharing data were consistent with sweetness as measured by HPLC. In conclusion, RAPD assays can be used for providing alternative markers for identifying genotypes and quantitative characteristics in watermelon.