The major thrust of sugarcane (Saccharum spp.) variety improvement programs is to increase sugar yield in addition to biomass and energy cane for biofuel production. However, due to its genetic complexity, sugarcane has received very little research interest, despite its economic importance, and molecular marker techniques are being developed only in recent times. Furthermore, until the present date few molecular studies were carried out to evaluate sugarcane germplasm in Ethiopia. Therefore, this study was conducted at Addis Ababa University, Genetic Research Laboratory to evaluate molecular genetic diversity and establish relationships among genotypes and populations of introduced sugarcane in Ethiopia using ISSR molecular markers. Genomic DNA was extracted from silica-gel-dried leaf samples of 82 sugarcane genotypes according to cetyltrimethylammonium bromide (CTAB) method. A total of 149 scorable and reproducible bands were generated using 12 ISSR primers among which 124 were polymorphic and attributed to percentage of polymorphic loci (PPL) = 83.22%, Nei’s gene diversity (h) = 0.31, and Shannon’s information index (I) = 0.45 at genotypic level. The number and percentage of polymorphic loci of the marker ranged from 7 to 16 and 70 to 90.91%, respectively. Intra-population diversity based on percentage of polymorphic loci ranged from 28.86 to 47.65% with mean of 38.35%, Nei’s gene diversity of 0.097 to 0.171 with mean of 0.137, Shannon’s information index of 0.147 to 0.255 with mean of 0.205. Partitioning the genetic variation by AMOVA further revealed that 63.56% of the total genetic variation occurred among genotypes within population and 36.4% among population. All diversity index parameters confirm that the highest diversity was obtained from those that were obtained from France and Cuba whilst the lowest was from those of Barbados and South Africa. From Jaccard’s pairwise similarity coefficient, pairwise comparison of the seven populations of sugarcane, the genetic identity values were ranged from 0.532 to 0.700 with mean of 0.616. With all clustering analysis, most of the genotypes clustered to their respective geographical origins as there was some mixture of genotypes from different origins in the different clustering groups. The level of polymorphism observed proved that the ISSR marker system was robust at amplifying markers on sugarcane. Thus, ISSR markers detected a range of diversity from investigated sugarcane genotypes with their unique identity that deserve conservation attention and improvement programs. This molecular-based genetic information can be used for establishing proper identity of the genotypes, strategic conservation of these germplasm resources, and future improvement work of the sugarcane crop through selecting the appropriate parents in their breeding programs to maximize sugar yield and maintaining genetic diversity.
Key words: Ethiopia, genetic diversity, inter simple sequence repeat (ISSR), sugarcane.
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