Genetic diversity of endangered date palm (Phoenix dactylifera L.) in the oases of Nefzaoua, Tunisia, using SSR markers

Introduction - Date palm (Phoenix dactylifera L.) is a dioecious monocotyledon perennial fruit-bearing plant belonging to the palm family Palmae or Arecaceae. The present study consisted of the characterization of the genetic relationships among 21 endangered date palm genotypes from 11 oases of Nefzaoua, Southwestern Tunisia. Materials and methods - The genetic data was obtained using eight highly polymorphic SSR loci. Results and discussion - The results revealed that the eight pairs of primers used amplified 48 alleles in the accessions studied, showing a high level of polymorphism with little geographical structure among the oases analyzed. The number of alleles per locus ranged from three (mPdCIR063) to eight (mPdCIR078) with a mean value of 6 alleles per locus. The average of observed heterozygosity (Ho), ranged between 0.38 (mPdCIR078) and 0.80 (mPdCIR010), with a mean of 0.603. The average of expected heterozygosity (He) ranged between 0.54 (mPdCIR035) and 0.78 (mPdCIR025) with a mean of 0.682. UPGMA cluster analysis grouped the date palm accessions analyzed in four groups. Conclusion - Genetic diversity among the accessions studied is high, as found in previous studies, while the genetic structure is low and does not seem to follow a geographical pattern. The results validate the use of SSR markers in order to analyze the diversity of Tunisian endangered date palm germplasm and optimize conservation measures.