Analysis of genetic diversity and population structure among exotic sugarcane (Saccharum spp.) cultivars in Ethiopia using simple sequence repeats (SSR) molecular markers

摘要

The present study was performed to study genetic relationships and population differentiation of 90 introduced sugarcane accessions in Ethiopia by means of 22 SSR molecular markers. The 22 SSR markers amplified a total of 260 alleles, of which 230 were poly-morphic with a mean of 10.45 alleles per SSR locus. The range in allele number was 4–22. A high level of polymorphism with a mean of 60.51% polymorphic loci within the genotypes was detected. The polymorphic information content (PIC) ranged from 0.231 to 0.375 with an average of 0.303. Measures of effective number of alleles and genetic diversity on average were 1.55 and 0.317, respectively, across all the 22 markers evaluated. The SSR genetic profiles obtained using the 22 markers enabled complete discrimination among all the 90 introduced sugarcane cultivars. The neighbor- joining unweighted pair group method with arithmetic mean (UPGMA) cluster analysis based on the simple matching dissimilarity indices unambiguously distinguished all sugarcane genotypes with three major clusters and 11 groups. The same clustering pattern was also found in the PCoA analysis. In all the geographical populations, genotypes from the same country were often in different clusters and likewise accessions from different countries often clustered together indicating the possibility of exchange of materials between countries. Population genetic differentiation showed Fst values among pairs of populations ranging from 0.0024 to 0.5134 with an overall average of 0.0590. The average gene flow (Nm) among populations was 1.7213. Nei’s unbiased genetic distance ranged from 0.018 to 0.279 with an overall average of 0.053. Genetic identity values were in the range of 0.756 to 0.992 with overall average of 0.950. The genetic relationship information of the cultivars will help sugarcane breeders to select the appropriate parents in their breeding programs to maximize yield as well as to maintain genetic diversity.