MOLECULAR ANALYSIS OF GENETIC DIVERSITY AND POPULATION STRUCTURE OF LOCAL SUGARCANE GENOTYPES IN ETHIOPIA

Aim: To assess genetic variability/diversity and study population structure among local sugarcane germplasm collections in Ethiopia using SSR markers.

Place and Duration of Study: Laboratory of Department of Biotechnology, Sugarcane Breeding Institute, Tamil Nadu State, Coimbatore, India, between November 2012 and February 2013.

Methodology: For genomic DNA isolation young leaves of 100 local sugarcane genotypes growing in different geographic regions of Ethiopia by small holder farmers were used. Genetic diversity and population structure of the genotypes was evaluated using twenty two SSR markers.

Results: The markers amplified a total of 260 alleles, of which 225 (86.5%) were poly­morphic with a mean of 10.2 alleles per SSR locus. The high number of alleles and polymorphic nature of these SSR markers indicated their robustness in quantifying the genetic diversity of sugarcane cultivars. The range in allele number was 4–22. PIC values ranged from 0.214 to 0.348 with an average of 0.291. Measures of effective number of alleles and genetic diversity on average were 1.52 and 0.299, respectively, across all the 22 markers evaluated. Cluster and PCoA analysis assigned clones into three main distinct clusters and nine major groups. Genotypes were grouped in separate clusters irrespective of their geographic location. FST values among pairs of populations ranged from 0.0018 (between Tigray and Gambella) to 0.4003 (between Benshangul-Gumz and Amhara) with an overall average of 0.0903. The average gene flow (Nm) among populations was equal to 1.6907. Average Nei’s unbiased genetic distance was high (0.167) between Tigray and SNNPR populations and low (0.001) between accessions of Oromia and Amhara. Genetic identity values were in the range of 0.791 to 1.000.

Conclusion: High level of local sugarcane germplasm genetic diversity is present in Ethiopia, the genetic relationship information of the cultivars will help sugarcane breeders to select the appropriate parents in their breeding programs to maximize yield, maintain diversity as well as developing mapping population.