Genetic diversity and population structure of Tunisian wild Kermes oak (Quercus coccifera L.): Assessment by ISSR molecular markers and implication for conservation.

BACKGROUND: In Tunisia, Kermes oak (Quercus coccifera L.) populations are severely destroyed due to deforestation. Nowadays, no preservation programs are attempted, yet, to conserve and promote the potential value of this resource. In this work, we assessed the genetic diversity of seven natural Tunisian populations of Q. coccifera from different bioclimates using Inter-Simple Sequence Repeats molecular markers. The distribution of the genetic diversity of Q. coccifera constitutes the pioneer step in the process of the conservation of the species. METHODS AND RESULTS: Nine selected ISSR markers were analyzed to characterize the genetic profiles of 70 different genotypes. The ISSR primers produced 64 loci ranging from 6 (UBC809 and UBC810) to 9 (UBC873) with an average of 7.11 at the species level. The average percentage of the polymorphic loci varied from 64.06% (Tabarka) to 76.56% (El Haouaria). The analyzed genotypes (70 individuals) revealed a high level of genetic diversity at species level (Na = 1.697; Ne = 1.517; He = 0.289; I = 0.418). The major proportion of the variation was attributable to individual differences within populations (76.07%). Analysis of molecular variance revealed also significant differentiation among all populations (ΦST = 0.245) and among populations within bioclimates (ΦSC = 0.233), even at a low scale space. The UPGMA and the PCoA analyses showed that most populations clustered independently to bioclimate or geographical distance indicating that genetic differentiation mainly occurs at local space scale due to genetic drift. CONCLUSIONS: The in-situ conservation of the species should be maintained on natural populations as a forest genetic resources. Moreover, ex-situ conservation should involve the selection of genotypes with extensive collection of seeds and cuttings from different populations of the target area.

Genetic relationships among subspecies of Capparis spinosa L. from Tunisia by using ISSR markers.

In Tunisia, Capparis spinosa L. is widely distributed in different geographic areas. Although it has been extensively studied morphologically, the phylogenetic relationships by using molecular markers among Capparis taxa are still unclear. The Inter-Simple Sequence Repeats (ISSR) molecular markers were used to assess the genetic relationship of this species cultivated in the North and the South of Tunisia. Fifteen ISSR primers were analyzed to characterize the genetic profiles of 67 different genotypes. The ISSR markers produced 108 bands ranging from 4 (ISSR8) to 11 (IAM12 and ISSR16) with an average of 7.2. The observed heterozygosity ranged from 0.43 to 0.95 for ISSR7 and IAM12, respectively. The Polymorphic Information Content (PIC) ranged from 0.48 at the UBC808 to 0.85 at IAM12 and eight loci could be classified as useful for genetic mapping (PIC > 0.7). The genetic diversity within a population was high and varied according to the subspecies and bioclimatic zones. Both UPGMA (Unweighted Pair Group Method with Arithmetic mean) and PCoA (Principal Coordinate Analysis) analyses showed that populations from each subspecies grouped together. However, the structure analysis generated more groups than the PCoA plot and UPGMA, which revealed the mixed allelic of the species Capparis spinosa in Tunisia.