Molecular variance of the Tunisian almond germplasm assessed by simple sequence repeat (SSR) markers

The genetic variance analysis of 82 almond (Prunus dulcis Mill.) genotypes was performed using ten genomic simple sequence repeats (SSRs). A total of 50 genotypes from Tunisia including local landraces identified while prospecting the different sites of Bizerte and Sidi Bouzid (Northern and central parts) which are the most important locations of almond diversity in Tunisia were included. Analysis of molecular variance (AMOVA) was  performed for 11 populations from these different regions and foreign countries to examine the distribution of genetic variation of the accessions studied. Results show that the major variation occurred within populations in each geographic site. Additionally, this analysis demonstrates that the genetic diversity within local almond cultivars was important, with a clear geographic distinction between the Northern and the Southern Tunisian cultivars. The value of prospecting new sites, preserving genetic diversity and encouraging on farmers almond collections is also discussed.Keywords: Prunus dulcis Mill., Genetic resources, AMOVA, local ecotypes, geographic origin, TunisiaAfrican Journal of Biotechnology Vol. 12(29), pp. 4569-457

Usefulness of microsatellites for positioning the tunisian almond germplasm in its mediterranean geographic context.

6 Pags.- 1 Tabl.- 1 Fig. The definitive version is available at: http://www.actahort.org/index.htmIn Tunisia, the almond tree (Prunus dulcis), dating back to ancient times, has been grown extensively since the Carthaginian era. In the framework of a national project on the characterisation and the conservation of the local almond germplasm many morphological and molecular markers (RAPD and SSR) have been used in order to analyse the genetic diversity of the main almond cultivars and to seek for the genetic position of these resources in the Mediterranean basin. For this study, 10 SSRs were used to analyse 82 almond accessions from different origins. Most of them originated from Tunisia (50), the others included in the National collection were from France (9), Italy (7), Morocco (1), Spain (8), USA (3), or were of unknown origin (4). The dendrogram based on UPGMA analysis using the similarity matrix generated by the Nei and Li (1979) coefficient presented four main clusters (A, B, C and D). In group A were present 40 of the 50 local genotypes that originate from the centre and the south contrarily, all cultivars from the north were in group C and clustered with the European and American genotypes. Accordingly, our study stressed the large diversity of the Tunisian almonds and revealed the presence of two distinct genetic groups. One located in the north genetically close to the gene pool of the Northern border of the Mediterranean and the second in the central and southern part that is highly adapted to different abiotic stress mainly drought.Peer reviewe

Usefulness of microsatellites for positioning the Tunisian almond germplasm in its Mediterranean geographic context

Póster presentado en la VI International Symposium on Almond and Pistachios, celebrado en Murcia del 27 al 31 de mayo de 2013.Microsatellites or SSRs are currently being employed for molecular characterization, estimation of genetic diversity and genetic relationships among almond cultivars and related Prunus species. As little information is available about the genetic diversity and relatedness within Tunisian almond cultivars and their relationship with the others originated from other countries, the aims of this work are to identify by SSR analysis the cultivars preserved in the Tunisian National Collection and the landraces collected directly from different sites of the country (Sidi Bouzid and Bizerte), to determine their relatedness to European and American cultivars and to estimate the level of genetic diversity.Peer Reviewe

Effectiveness of molecular markers for almond germplasm management

Proceedings of the V International Symposium on Pistachios and Almonds. Eds.: B.E. Ak, M. Wirthensohn and T. Gradziel. Acta Hort. 912, ISHS 2011Tunisia was one of the main routes used to spread almond all over the Mediterranean region which explains the high diversity noted during recent prospections. In the framework of GREMPA a collection of almond was established in Sfax in the early seventies from which many others were derived. While quantitative and biochemical parameters are environmental dependant molecular markers offer a means to identify and characterise the relationships among cultivars and accessions and for germplasm management. Since little molecular information is available regarding almond cultivars grown in Tunisia, the present study aimed to reveal the genetic diversity and relatedness among the most important Tunisian almond cultivars and to analyse the authenticity of the most important local cultivars preserved in the national collection of >Ettaous>. While comparing 60 almond cultivars, by random amplification of their DNAs with 12 primers, 117 bands were detected, of which 92 were polymorphic (78, 6%). The information obtained from this work was useful for National Collections management and has revealed many duplications and mislabelling for the existing genotypes.Peer Reviewe

Physical properties, biochemical and antioxidant contents of new promising Tunisian almond genotypes: Traits stability, quality aspects and post-harvest attributes

The specific approach of any fruit tree genetic resources preservation program depends undoubtedly on the valorization of the autochthonous germplasm with noticeable traits related to quality and adaptation to harsh climatic conditions. In this context, pomological and biochemical properties of 15 chance seedling almond genotypes, 11 old local Tunisian cultivars and 5 foreign introductions from different origins were studied in order to evaluate possibilities for their commercial and industrial valorization features. Parameters with high discriminating values were more related to kernel weight and width, shelling percentage, oleic and linoleic acids, tocopherols, sugar and protein contents. On the other hand, oil and protein contents were highly variable between genotypes, ranging respectively from 42.6 to 61 % and from 14.5 to 28.3 % of the total kernel dry weight. Main fatty acids ranged between 5.9–7.5 % for palmitic acid, 60.3–76.5 % for oleic acid, and 13.4–28.9 % for linoleic acid. The range of variation of tocopherols, was large for α-tocopherol (208.3–629.2 mg kgoil) and for γ-tocopherol (2.8–21.9 mg kgoil). Although the physical performances of the kernels for some accessions were in general low, their interesting chemical composition offers the possibility of many alternative uses which could improve their marketable value. In addition, some genotypes were singled out as the most promising for varied commercial finalities. ‘Porto’ and ‘Blanco’ were characterized by high stable total sugar and sucrose contents. Moreover, ‘Blanco’ had the highest α-, γ- and δ-tocopherol contents. ‘Guernghzel’, ‘Ras Bouma’ and ‘Forme en Poire’ were a rich source of protein while ‘Mahsouna’ and ‘Achaak’ may be a potential source for almond oil extraction. All of the understudied ‘K.Friji1’, ‘Bouchouka’ and ‘Forme en Poire’ oils had powerful antioxidant effects due to their high α-tocopherol content. ‘Sahnoun’ and ‘Zahaaf’ presented valuable oil with high oleic acid content. Thus, newly identified genotypes with high performances compared to the introduced cultivars represent a very promising base for breeders to generate new local almond cultivars with high quality kernel and oil that might be used for edible and industrial purposes.This study has been supported by the Institution for Agricultural Research and Higher Education of Tunisia (IRESA), the Spanish Agency for International Cooperation and Development (AECID) and ARIMNET-2 European project (NUT4Drought

Kernel quality evaluation of promising new almond germplasm grown in mountain and oasis agro-systems in Morocco

The main physicochemical traits of almond kernel were determined in 26 selected local almond [Prunus dulcis (Mill.) D.A. Webb, syn. P. amygdalus (L.) Batsch] seedlings grown in four localities under two different agro-ecological systems, Mountains (Al-Hoceima and Azilal) and oasis ecosystem (Agdez and Skoura). Nut and kernel weight varied widely among genotypes, year and population. Most genotypes exhibited small to intermediate kernel weight, ranging from 0.9 to 1.4 g. All these genotypes are hard shelled with shelling percentages lower than 25%. Kernels produced at Agdez and Skoura (oasis ecosystems) are slightly heavier than those of other localities (mountains regions). Natural variability was observed among genotypes for oil content, ranging from 50 to 61% on a dry weight (DW) basis. For protein content, the value varied between 18.24 and 29.16% DW. The year effect was significant on oil and protein content. In agreement with the oil content, the protein content of the kernels produced in oasis ecosystem [Agdez (24.84% DW) and Skoura (24.58 DW)] was higher than those collected in mountain regions [Azilal (22.35% DW) and Al-Hoceima (22.54% DW)]. The analysis of fatty acids demonstrated a significant variability among genotypes for palmitoleic (5.49–7.53%), palmitic (0.35–0.64%), stearic (1.42–2.80%), oleic (61.55–76.68%) and linoleic (13.58–27.7%) acid percentages with a significant year effect. Over the two studied years, the oleic acid was higher and the linoleic acid was lower in kernels of almond grown under oasis ecosystem than in those from mountains regions. The high quality of almond kernel produced in oasis ecosystem could be due to the favourable oasis micro-climate and to the periodic supply of water and nitrogen to the underlying crops that are inter-planted with almond; however in the mountains regions, the almond is grown under drought conditions without any supplemental irrigation or technical support.This work was supported by the Nut4Drought from ARIMNET-2 European Progra

Development of an SSR-based identification key for Tunisian local almonds

19 Pags., 4 Figs., 2 Tabls.Ten simple sequence repeat (SSR) loci were used to study polymorphism in 54 almond genotypes. All genotypes used in this study originated from almond-growing areas in Tunisia with different climatic conditions ranging from the sub-humid to the arid and are preserved in the national collection at Sidi Bouzid. Using ten SSR, 130 alleles and 250 genotypes were revealed. In order to develop an identification key for each accession, the data were analysed separately for each microsatellite marker. The most polymorphic microsatellite (CPDCT042) was used as a first marker. Two microsatellite loci (CPDCT042 and CPDCT025) were sufficient to discriminate among all accessions studied. Neighbour-joining clustering and principal coordinate analysis were performed to arrange the genotypes according to their genetic relationships and origin. The results are discussed in the context of almond collection management, conformity checks, identification of homonyms, and screening of the local almond germplasm. Furthermore, this microsatellite-based key is a first step toward a marker-assisted identification almond database.Financial support was provided in part by the Tunisian Ministry of Higher Education, Scientific Research and Technology, the Spanish Ministry of Science and Innovation (AGL2008-00283/AGR co-financed by FEDER), the Aragon Government (Group A44), and the Agencia Española de Cooperación Internacional (A/5339/06 and A/8334/07).Peer reviewe