Assessment of the Genetic Diversity among Wild Colocynth (Citrullus colocynthis (L.)Schrad.) Ecotypes Collected from Different Regions of Sudan

Abstract

Better utilization and conservation of the medicinal and aromatic plants (MAP), most of which are collected from the wild, necessitate their screening to identify potential genotypes for both production and utilization in interbreeding to develop superior genotypes.The objective of this research, therefore,wasthe assessment of the genetic relationship among wild colocynth Citrullus colocynthis (L.)Schrad. ecotypes. Seeds of twelve colocynth plants (SF, K10, K10₁, K114, ABD, SH, G, GD, GD1, ND, SD and NK) were collected from wild plants growing in twelve diverse ecologies of Sudan’s States. Commercial watermelon (Wm) seeds were obtained from the seed store and tested for comparison. Randomly Amplified Polymorphic DNA (RAPD) technology was used to explore the genetic relatedness of the ecotypes. Ten RAPD primers were used to amplify CTAB-extracted DNA from leaves of each ecotype. Data were used to create similarity matrices using the PAST 3.01 software package and a dendrogram was constructed based on Jaccard’s similarity coefficients. A total of 321 DNA fragments were detected by RAPD markers for the 13 tested plants giving an average of 24.69 alleles per ecotype. The number of fragments detected for each ecotype ranged from 11 (GD) to 64 detected for K10; ten fragments were detected for watermelon. Hundred percent polymorphism was recorded for the tested primers with high Polymorphism Information Content (PIC) values in the range of 0.97-1.00. Similarity matrix constructed from data generated indicated that the closest ecotypes, with 67% similarity, were ABD and K114, while the most distant ones (no similarity) were SD and GD as well as GD and Wm. The constructed dendrogram divided the 12 colocynth ecotypes and the watermelon cultivar into three major clusters; the first includes watermelon cultivar as an out-group, the second includes all ecotypes except K10 which is grouped in a separate cluster. These results conclude that the ecological zone does not affect the genetic relatedness of the tested ecotypes despite their high genetic polymorphism. The variability between the ecotypes points out that Sudan’s colocynth germplasm possesses high potentiality for future improvement through crossing and selection.