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Genetic diversity and structure of seven natural populations of Teucrium polium were assessed using forty-six electrophoretic bands revealed by seven isozymes, and 144 RAPD loci amplified by eight primers. The analysed populations are diploid (population of Sakiet Sidi Youssef and Dj. Douaou), tetraploid (populations of Korbous, Dj. Ezzit, Sidi Khlifa, and Toujane), and hexaploid (population of Kerkena) and belonged to five bioclimatic zones.

Additional isozyme bands were detected in the polyploid populations when analysed by isozymes. The percentage of polymorphism ranged from 19.5 to 58.7% according to a population. Population structure assessed by a principal component analysis (PCA) based on electrophoretic bands frequencies concords with the ploidy level and the bioclimatic appurtenance.

The percentage of polymorphic RAPD loci was high (87.06%). It ranged from 38.3 to 53.9% according to a population. Particular RAPD loci were detected mainly in the polyploid upper arid populations. A high differentiation among polyploid populations from the upper arid bio-climate and the other populations was revealed by the PCA performed on the amplified DNA fragment's frequencies.

The two sets of data significantly correlated (r=0.70; P<0.05). However, population structure assessed by a PCA based on the combined matrices (isozyme and RAPD bands frequencies) was more similar to that observed using only RAPD markers.