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Rosemary plant is in high demand due to its application in traditional health care, food flavoring, fragrance and pharmaceutical industries. It contains high level of secondary metabolites which are responsible for its beneficial activities. Application of molecular techniques would facilitate the production of these substances and screening of accessions. The isolation of polymerase chain reaction (PCR) amplifiable genomic DNA is a prerequisite for taking advantage of these technologies. Even though several DNA isolation protocols for plants with high level of secondary metabolites were developed, they may not permit optimal DNA extraction due to chemotypic variation within species. Extracting DNA from different rosemary accessions is a challenging task due to its high level of secondary metabolites. Therefore, this research is conducted with the aim of optimizing a reliable and rapid method suitable for extracting DNA from rosemary plants. The optimized protocol avoids the use of repeated toxic phenols, liquid nitrogen and large polypropylene tube. It is appropriate for both fresh and dry leaf samples. The quality of the obtained DNA was excellent as evident by A 260 /A 280 ratio ranging from 1.7 to 1.89 and the concentration ranged from 195.8 to 2184 ng/µl. The success of this protocol indicated its applicability for other plants with high secondary metabolite contents.

Forty-five rosemary genotypes collected from different parts of Ethiopia were evaluated for quantitative morphological traits to estimate the genetic variability, heritability and association of characters. The genotypes displayed significant differences for all of the studied traits, showing the presence of wide variability among the tested genotypes. The genotypic and phenotypic coefficients of variation were found to be medium and high for all growth and yield traits except for leaf length. Moderately high to high broad-sense heritability (0.66 -0.97) coupled with moderate to high genetic advance as a percent of the mean (10.37 -79.14) values were found for all traits.  Correlation coefficient and path coefficient analysis revealed that characters vis. branch number plant-1, fresh leaf weight plant-1, dry leaf weight plant-1, fresh leaf yield ha-1, and essential oil content had a high positive direct effect and significant positive association with essential oil yield ha-1. Thus direct selection for these traits would be quite effective for essential oil yield enhancement in rosemary. In general, the studied accessions were diverse in nature and could be exploited in the conservation, breeding and commercialization of the crop.