Analysis of genetic diversity in rosemary (Salvia rosemarinus Schleid.) using SSR molecular marker for its management and sustainable use in Ethiopian genebank

Abstract

Rosemary (Salvia rosemarinus Schleid.) is cultivated worldwide due to its diverse uses as spice, preservative and medicine against many illnesses. Even though rosemary is widely grown in Ethiopia, the genetic diversity of available germplasms was not assessed. Therefore, this experiment was designed to analyze the genetic diversity of Ethiopian rosemary for further breeding activities. Genetic diversity of 45 rosemary accessions collected from different parts of Ethiopia was analyzed using 12 simple sequence repeat markers. A total of 189 alleles were detected, and the number of alleles per marker (Na) ranged from 7 to 27 with an average of 15.75. About 56.6% of the alleles were rare (frequency 0.5), respectively. Polymorphic information content per marker ranged from 0.74 to 0.94, with an average value of 0.87. The result depicted over all polymorphism of 92.6%, indicating the existence of high genetic variability among the accessions. The average values of expected (HE) and observed (HO) heterozygosities were 0.65 and 0.35, respectively. The average HO was lower than HE, showed heterozygote deficiency due to restricted cross-fertilization. Analysis of molecular variance revealed that within populations variations contributed more to the genetic diversity than between population variations. Unweighted Neighbor Joining based phylogenetic analysis, Principal Coordinate analysis and STRUCTURE analysis showed admixture of the populations, confirming that the sample groupings did not strictly follow the geographic origin of the accessions. Therefore, improvement program of the crop should focus on actual diversity, not on area of growing.