Chloroplast DNA Diversity of Tunisian Barley Landraces as Revealed by cpSSRs Molecular Markers and Implication for Conservation Strategies

In Tunisia, barley local landraces are still cropped for human and animal consumption in some subsistence farming systems under marginal and stressed conditions. These high-value genetic resources present a potential source of resistance genes to biotic and abiotic stresses useful for both national and international breeders. Actually, they are represented by threatened small populations, which face a high risk of genetic erosion and progressive substitution by modern varieties. In this study, the genetic diversity of 60 Tunisian barley landraces was assessed using six chloroplast microsatellites. All loci were found polymorphic, with 2 or 3 alleles per locus. Thirteen alleles were detected across the studied sample, which were combined into 8 haplotypes, giving a haplotype diversity (Hd) of 0.847. High punctual and haplotype genetic diversity was observed for Tunisian barley landraces when compared to other germplasms from other regions of the world. The genetic structure analysis revealed two major clusters of Tunisian barley landraces, which confirms their multiorigin. This result was corroborated by the median-joining network showing the genetic relationships among the eight detected haplotypes. The AMOVA analysis revealed that 83% of the genetic variation is between populations, which requires the in situ and ex situ conservation of plant material for all Tunisian populations of barley landraces. Information on genetic variation within the chloroplast genome is of great interest to ensure an efficient conservation strategy that takes into account the preservation of the various maternal lineages of Tunisian barley

Data from: Conservation priorities for endangered coastal North African Pennisetum glaucum L. landrace populations as inferred from phylogenetic considerations and population structure analysis

The increasing anthropologic pressure and the modernization of agriculture have led to a forsaking of pearl millet traditional cultivars inducing a progressive loss of the genetic variability encompassed in this locally-adapted germplasm. Imperatively, national efforts based on robust data gleaned from genetic surveys have to be undertaken in order to set up suitable conservation priorities. Inthis study, in addition to the assessment of the genetic diversity and population structure among and within a set of seven pearl millet landrace populations from coastal North Africa, demographic and phylogenetic data, conservation priority scores were calculated according to Vane-Wright et al. (1991). To date, genetic diversity of pearl millet in North Africa is still poorly documented. The present survey reports for the first time the use of highly informative nSSR markers (PIC =0.74) on P. glaucum landraces representative of the Mediterranean coastline of North Africa. A high level of genetic diversity was obtained within the investigated landraces (He=0.80) at the population level. FST, AFC-3D and Bayesian clustering underlined significant differentiation and an apparent genetic structure according to geographical origin. Phylogenetic considerations integrated with demographic and genetic information enabled conclusive inferences of highly prioritized populations for conservation. Populations Haouaria, Hammem Laghzez, Mahdia and Medenine representatives of the main pearl millet growing areas in Tunisia and cultivated in the North African littoral should be strongly recommended for an ex-situ conservation program. Dynamic on-farm conservation method is also required as it allows to the local landraces to evolve in different environments while maintaining their adaptation potentials