Genetic diversity of 50 Tunisian almond (Prunus dulcis Mill.) genotypes and their relationships to European and American cultivars were studied. In total 82 genotypes were analyzed using ten genomic SSRs. A total of 159 alleles were scored and their sizes ranged from 116 to 227 bp. The number of alleles per locus varied from 12 to 23 with an average of 15.9 alleles per locus. Mean expected and observed heterozygosities were 0.86 and 0.68, respectively. The total value for the probability of identity was 4 × 10(-13) . All SSRs were polymorphic and they were able all together to distinguish unambiguously the 82 genotypes. The Dice similarity coefficient was calculated for all pair wise and was used to construct an UPGMA dendrogram. The results demonstrated that the genetic diversity within local almond cultivars was important, with clear geographic divergence between the northern and the southern Tunisian cultivars. The usefulness of SSR markers for almond fingerprinting, detection of synonyms and homonyms and evaluation of the genetic diversity in the Tunisian almond germplasm was also discussed. The results confirm the potential value of genetic diversity preservation for future breeding programs.

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Original article and medical properties, including healthy blood lipids levels, anti-inflammatory and hypocholesterolemic properties (Poonam et al., 2011; García et al., 2016; Musa-Velasco et al., 2016). Almond production in Tunisia is based on the use of locally adapted clones and traditional management practices with minimal to no inputs. These local cultivars are commonly grown in areas between 33° and 36°N and 8° and 10°E, and at altitudes between 13 and 400 m. These almond production areas include a humid climate zone in the north of Tunisia, with an average annual rainfall of more than 700 mm, and a semi-arid climate zone in the centre that receives around 200 mm of rain per year (Figure 1). The cultivation of this species was introduced in Tunisia by the Phoenicians in the 12 th century B.C. Starting in the early 20 th century, many pomologists identified genotypes that were later propagated and considered as cultivars. This was the case in Sfax (southeast Tunisia) for the main cultivars, which are called 'Sfaxien' cultivars: ' Abiodh', 'Ksantini', 'Grosse Tendre', 'Guernghzel' and ' Achaak' (Grasselly and Crossa-Raynaud, 1980). Currently, we have about 20 million almond trees in Tunisia occupying more than 250,000 ha. Almond cultivation is mostly non-irrigated with kernel yields of around 350 kg ha-1 , which is much lower than the 2,300 kg ha-1 in the US, where the production (limited to California) is much more intensive and exclusively irrigated (http:// faostat.fao.org). Grasselly and Crossa-Raynaud (1980) were the first to briefly describe the Tunisian germplasm diversity and to give an overview of the morphological characteristics (shell hardness, fruit shape, kernel percentage and blooming time) of several local almond cultivars. Since then, the need to characterise and preserve the local germplasm German Society for Horticultural Science Summary Almonds have been cultivated in Tunisia since ancient times. Due to increasingly severe dry conditions, the local almond gene pool has significantly decreased since the 1980's. In order to rescue the remaining almond germplasm and to investigate the existing agronomical variation in Tunisia, a survey was undertaken several years ago to identify and preserve the traditional almond cultivars. In this study, 52 local almond cultivars and ecotypes were evaluated for three consecutive years, and 18 different tree, kernel and nut traits were observed. Results show a great diversity of almond ecotypes and cultivars in Tunisia. Kernel weight and size and adaptation to dry conditions are the most interesting qualities of this local germplasm. However, self-incompatibility, early flowering and the presence of double kernels are the most common obstacles for using this germplasm in breeding. Furthermore, principal component analysis was used to identify morphological variation patterns and to classify the genotypes. In this analysis, the first three retained principal components were found to explain more than 56% of the total variance. The main nut traits, such as le...

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