Genetic Diversity, Phylogeography and Population gene flow of Tunisian Pistacia vera L.

Abstract

The aim of this paper was to determine how the pistachio trees evolve, and the evolving factors that influence pistachiopopulation establishment. For that, we investigated pistachio genetic structure from some regions of Tunisia, by sequencing twononcoding chloroplastic regions (trnL (UAA) and trnL-trnF intergenic spacer). We found strong genetic diversity among groups, withthe absence of high differentiation between population pairs. A deep phylogeographical break separated two major clusters: “El-Guetarand “Gafsa/Sidi-Bouzid. This conclusion is proved by the haplotype networks, the phylogenetic trees, and the molecular variance analysis.Different interpretations were proposed to explain this cytoplasm dimorphism, based on the molecular evolution and demographichistory analysis: (1) the domestication events, which are very important to understand the variability between the prospective areas, (2)the gene flow between them, a process that occurs both in time and in space through pollen and seeds, and strongly interacts with thelocal farming systems, (3) the geographical barriers that exist, which limit gene flow transfer and make particular climatic conditions ofthe El-Guetar oasis. Given that, the genetic diversity study within Tunisian pistachio cultivars is very useful to contribute to the nationalmanagement effort for the improvement and conservation of pistachio genetic resources. Moreover, in 2017, Tunisia ranked among thetop 10 countries in global pistachio production. Thus, studying the diversity of Tunisian pistachio can make an important impact onglobal production