Grafting versus seed propagated apricot populations: two main gene pools in Tunisia evidenced by SSR markers and model-based Bayesian clustering Hedia Bourguiba, Bouchaib Khadari, Lamia Krichen, Neila Trifi-Farah, Sylvain Santoni, Jean Marc Audergon To cite this version: Hedia Bourguiba, Bouchaib Khadari, Lamia Krichen, Neila Trifi-Farah, Sylvain Santoni, et al.. Graft- ing versus seed propagated apricot populations: two main gene pools in Tunisia evidenced by SSR markers and model-based Bayesian clustering. Genetica, Springer Verlag, 2010, 138 (9-10), pp.1023- 1032. 10.1007/s10709-010-9488-2. hal-01250497 HAL Id: hal-01250497 https://hal.archives-ouvertes.fr/hal-01250497 Submitted on 4 Jan 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution - NonCommercial| 4.0 International License Genetica (2010) 138:1023–1032 DOI 10.1007/s10709-010-9488-2 ORIGINAL RESEARCH Grafting versus seed propagated apricot populations: two main gene pools in Tunisia evidenced by SSR markers and model-based Bayesian clustering Hedia Bourguiba • Bouchaib Khadari • Lamia Krichen • Neila Trifi-Farah • Sylvain Santoni • Jean-Marc Audergon Received: 12 October 2009 / Accepted: 16 August 2010 / Published online: 14 September 2010 Ó The Author(s) 2010. This article is published with open access at Springerlink.com Abstract Apricot was introduced into the Mediterranean largest part of the studied germplasm. According to their Basin from China and Asian mountains through the geographic origin, the five identified groups (north, centre, Middle-East and the Central Europe. Traditionally present south, Gafsa oasis and other oases groups) enclosed a in Tunisia, we were interested in accessing the origin of similar variation within group, with a low level of differ- apricot species in the country, and in particular in the entiation. Overall results highlighted the distinction of two number and the location of its introductions. A set of 82 apricot gene pools in Tunisia related to the different mode representative apricot accessions including 49 grafted cul- of propagation of the cultivars: grafted and seed propagated tivars and 33 seed propagated ‘Bargougs’ were genotyped apricot, which enclosed a narrow genetic basis. Our find- using 24 microsatellite loci revealing a total of 135 alleles. ings support the assumption that grafting and seed propa- The model-based Bayesian clustering analysis using both gated apricots shared the same origin. Structure and InStruct programs as well as the multivariate method revealed five distinct genetic clusters. The genetic Keywords Prunus armeniaca L. Á Domestication Á differentiation among clusters showed that cluster 1, with Rosaceae Á SSR Á Genetic structure only four cultivars, was the most differentiated from the four remaining genetic clusters, which constituted the Introduction H. Bourguiba Á J.-M. Audergon (&) INRA, UR1052 Ge´ne´tique et Ame´lioration des Fruits et Apricot (Prunus armeniaca L.) is a species of Prunus Le´gumes, Domaine Saint-Maurice, 84143 Montfavet, France genus belonging to the family Rosaceae that is commer- e-mail: [email protected] cially grown world-wide. Apricot is diploid (2n = 16) and H. Bourguiba Á B. Khadari has a small genome size (5.9 Mbp/2n) (Arumuganathan INRA, UMR 1098 De´veloppement et Ame´lioration des Plantes, and Earle 1991) compared to other fruit woody species as Campus CIRAD, TA A96/03 Avenue Agropolis, cherry (6.8 Mbp/2n) and apple (7.5 Mbp/2n) (Yuepeng and 34398 Montpellier cedex 5, France Korban 2007). Three centres of apricot origin were pro- H. Bourguiba Á L. Krichen Á N. Trifi-Farah posed by Vavilov (1992): north eastern, central and wes- Laboratoire de Ge´ne´tique Mole´culaire, Immunologie et tern China, central Asian mountains and near-eastern Biotechnologie, Faculte´ des Sciences de Tunis, Campus centre. Apricot was introduced into the Mediterranean Universitaire, 2092 El Manar, Tunisia Basin through two different ways. The first one was B. Khadari through the Middle-East allowing the identification of the Conservatoire Botanique National Me´diterrane´en, UMR 1098, Irano-Caucasian group (Kostina 1969) and the second was 34000 Montpellier cedex 1, France through the Central Europe (Faust et al. 1998). Four apricot cultivar groups named ‘Diversification’, ‘Geographically S. Santoni INRA, UMR 1097 Diversite´ et Adaptation des Plantes Cultive´es, Adaptable’, ‘Continental Europe’ and ‘Mediterranean 2 Place Viala, 34060 Montpellier cedex 1, France Basin’ were identified by Hagen et al. (2002). These groups 123 1024 Genetica (2010) 138:1023–1032 displayed a gradient of decreasing genetic diversity of cultivars and surveys were limited to some areas of apricot varieties from east to south-west. culture. In this paper, our investigations implied mapped Tunisia, one of the extreme dissemination zone of microsatellites markers covering the eight linkage groups apricot in the Mediterranean Basin, enclosed a strongly of Prunus genome to study a larger set of Tunisian apricot distinct gene pool of local apricot cultivars with a low germplasm including both grafting propagated cultivars genetic diversity compared to the four previously defined and seed propagated accessions. groups (Khadari et al. 2006). Apricot in Tunisia included We tested two working hypotheses related to the sce- traditional cultivars propagated by grafting, cultivated from narios described above: (a) two independent introductions, the north to the south of the country, and accessions a northern-central group including grafting propagated propagated by seeds, specific to oasis agrosystems, locally cultivars and a south-oasian group composed by seed called ‘Bargougs’ and characterized by their shadow con- propagated accessions; and (b) a single introduction fol- tribution to the oasian ecosystem. Khadari et al. (2006) lowed by a local diversification. For that purpose, a set of supported that seed propagation was more frequent than 82 apricot accessions including 49 grafted cultivars and 33 grafting propagation during apricot introduction in Tunisia. seed propagated ‘Bargougs’ was analyzed using 24 single- Thus, grafted cultivars could be the results of few intro- locus SSR markers, polymorphic in apricot species and duced genotypes which have been firstly propagated by selected throughout the Prunus genome. Using both mul- seeds. However, this hypothesis was not completely veri- tivariate analysis and model-based Bayesian clustering fied since the analysis was limited to only grafting propa- methods, we argued for the assumption that grafting and gated cultivars. Based on these results, a likely scenario seed propagated apricots shared the common origin. could be proposed considering that grafting propagated cultivars shared a same gene pool with seed propagated accessions supporting a single apricot introduction in Materials and methods Tunisia. An alternative scenario based on historical events suggested two main apricot introductions (Valdeyron and Plant material Crossa-Raynaud 1950; Carraut and Crossa-raynaud 1974). The first one, for the grafting propagated cultivars, was The plant material consisted of 82 Tunisian apricot located in the North of the country and originated from accessions including 49 cultivars propagated by grafting Andalusian germplasm, and the second one, for the seed and 33 spontaneous oasian ‘Bargougs’ propagated by propagated accessions, was situated in the South of Tunisia seeds. Surveys were conducted in the northern (Ras Jbel and originated from the Irano-Caucasian group. and Testour), central (Kairouan, Mahdia and Sfax), and Recently, several studies focused on characterization southern (Gabes and Jerba) areas of apricot culture in and genetic variability assessment of Tunisian apricot Tunisia and in six oasian zones (Gafsa, Midess, Tameghza, cultivars in order to preserve the local genetic resources Nefta, Tozeur and Degache; Fig. 1). Surveyed areas belong and to understand the evolution of apricot in south Medi- to the sub-humid bioclimatic zone for northern areas to the terranean areas. In fact, using microsatellites markers (or Saharan superior bioclimatic one for some oasis. The simple sequence repeats; SSRs), Krichen et al. (2006) studied accessions were classified into five geographic established an identification key for the discrimination of groups: north, centre, south, Gafsa oasis and other oases 54 cultivars on the basis of only five loci. While, using (Fig. 1). amplified fragment length polymorphism markers (AF- LPs), Khadari et al. (2006) compared the genetic diversity DNA extraction and microsatellite amplification among 31 grafting propagated Tunisian apricot cultivars and accessions from Europe, North America, Turkey, Iran Total genomic DNA was extracted from fresh young leaves and China, in order to give insights into the origin and according to Bernatzky and Tanksley (1986) protocol. historical selection process of local germplasm. Results Genotyping was conducted with a set of 24 SSR primers. revealed that Tunisian apricot constituted a distinct