Cultivated Olive Diversification at Local and Regional Scales: Evidence From the Genetic Characterization of French Genetic Resources Bouchaib Khadari, Ahmed El Bakkali, Laïla Khadari, Christine Tollon-Cordet, Christian Pinatel, Guillaume Besnard To cite this version: Bouchaib Khadari, Ahmed El Bakkali, Laïla Khadari, Christine Tollon-Cordet, Christian Pinatel, et al.. Cultivated Olive Diversification at Local and Regional Scales: Evidence From theGe- netic Characterization of French Genetic Resources. Frontiers in Plant Science, Frontiers, 2019, 10, 10.3389/fpls.2019.01593. hal-02620852 HAL Id: hal-02620852 https://hal.inrae.fr/hal-02620852 Submitted on 26 May 2020 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. 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Distributed under a Creative Commons Attribution| 4.0 International License ORIGINAL RESEARCH published: 24 December 2019 doi: 10.3389/fpls.2019.01593 Cultivated Olive Diversification at Local and Regional Scales: Evidence From the Genetic Characterization of French Genetic Resources Bouchaib Khadari 1,2*, Ahmed El Bakkali 3, Laila Essalouh 1,4, Christine Tollon 1, Christian Pinatel 5 and Guillaume Besnard 6 1 AGAP, University Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France, 2 Conservatoire Botanique National Méditerranéen de Porquerolles (CBNMed), UMR AGAP, Montpellier, France, 3 INRA, UR Amélioration des Plantes et Conservation des Ressources Phytogénétiques, Meknès, Morocco, 4 Établissement Public Local d’Enseignement et de Formation Professionnelle Agricoles Nîmes-Rodilhan-CFPPA du Gard, Rodilhan, France, 5 Centre Technique de l’Olivier, Maison des Agriculteurs, Aix-en-Provence, France, 6 CNRS-IRD-UPS EDB, UMR 5174, Université Paul Sabatier, Toulouse, France Molecular characterization of crop genetic resources is a powerful approach to elucidate the origin of varieties and facilitate local cultivar management. Here we aimed to decipher the origin and diversification of French local olive germplasm. The 113 olive accessions of the ex situ collection of Porquerolles were characterized with 20 nuclear microsatellites Edited by: plus their plastid haplotype. We then compared this collection to Mediterranean olive José Manuel Martínez-Rivas, varieties from the Worldwide Olive Germplasm Bank of Marrakech, Morocco. High genetic Instituto de la Grasa (IG), Spain diversity was observed within local French varieties, indicating a high admixture level, Reviewed by: Cristian Silvestri, with an almost equal contribution from the three main Mediterranean gene pools. Nearly Università degli Studi della Tuscia, Italy identical and closely related genotypes were observed among French and Italian/Spanish Enzo Perri, varieties. A high number of parent–offspring relationships were also detected among Council for Agricultural and Economics Research, Italy French varieties and between French and two Italian varieties (‘Frantoio’ and ‘Moraiolo’) *Correspondence: and the Spanish variety (‘Gordal Sevillana’). Our investigations indicated that French Bouchaib Khadari olive germplasm resulted from the diffusion of material from multiple origins followed by [email protected] diversification based on parentage relationships between varieties. We strongly suggest Specialty section: that farmers have been actively selecting olives based on local French varieties. French This article was submitted to olive agroecosystems more affected by unexpected frosts than southernmost regions Crop and Product Physiology, could also be seen as incubators and as a bridge between Italy and Spain that has a section of the journal Frontiers in Plant Science enhanced varietal olive diversification. Received: 05 August 2019 Keywords: Olea europaea L., parentage analysis, simple sequence repeat, genetic structure, ex situ collection of Accepted: 13 November 2019 Porquerolles, genetic resource management, core collection Published: 24 December 2019 Citation: Khadari B, El Bakkali A, Essalouh L, Tollon C, Pinatel C and Besnard G INTRODUCTION (2019) Cultivated Olive Diversification at Olive (Olea europaea L.) is the iconic fruit crop of the Mediterranean Basin. Archaeological, historical, Local and Regional Scales: Evidence From the Genetic Characterization of and genetic studies support a primary olive domestication in the Near East, probably starting during French Genetic Resources. the Chalcolithic period (Kaniewski et al., 2012; Zohary et al., 2012; Besnard et al., 2013b). Then Front. Plant Sci. 10:1593. long-distance translocation of varieties followed by admixture events led to secondary multi-local doi: 10.3389/fpls.2019.01593 diversification in central and western Mediterranean regions (Terral, 1997; Besnard et al., 2001a; Belaj Frontiers in Plant Science | www.frontiersin.org 1 December 2019 | Volume 10 | Article 1593 Khadari et al. Olive Diversification in French Agroecosystems et al., 2002; Owen et al., 2005; Baldoni et al., 2006; Breton et al., cultivars growing in the eastern and western sides of the 2008; Diez et al., 2015). Locally adapted varieties have thus been Rhone valley were differentiated (Khadari et al., 2003), possibly carefully selected by farmers in several Mediterranean areas and reflecting two pathways of olive cultivar introduction from the the domestication process is still ongoing (Besnard et al., 2001a; Italian and Iberian Peninsulas, respectively. Khadari et al., 2003; Khadari et al., 2008; El Bakkali et al., 2013a; In the present study, we investigated the cultivated olive Besnard et al., 2018). Selected trees are still both clonally and seed diversification process in southern France, with the aim of propagated in traditional agroecosystems from different parts of the determining ways to efficiently manage local olive genetic Mediterranean Basin (Aumeeruddy-Thomas et al., 2017; Besnard resources. Both nuclear and chloroplast loci were used to et al., 2018), implying a continuing role of sexual reproduction in characterize the genetic diversity of a set of varieties from the varietal diversification, with potential contributions from local French Olive Germplasm Bank (FOGB) in comparison to the domesticated, feral, and wild olives. Due to this diversification Worldwide Olive Germplasm Bank (WOGB) of Marrakech, process, a high frequency of parentage relationships could be Morocco (Haouane et al., 2011; El Bakkali et al., 2013b). We expected among varieties, as previously observed within the specifically aimed to: (1) assess genetic diversity within the Spanish olive germplasm (Diez et al., 2015) and in grapevine FOGB collection and propose a nested set of French reference (Bowers et al., 1999; Lacombe et al., 2013). Furthermore, farmer varieties representative of total genetic diversity; (2) compare the selection of newly adapted olive trees could be viewed as a key genetic diversity at two different geographical scales, i.e. local process in agroecosystems under changing climatic and ecological (France) and regional (Mediterranean area); and (3) clarify the conditions, such as those on the fringe of olive growing areas. But origin of French olive germplasm by parentage analyses within it is still unknown how farmer selection and varietal diversity and among French and Mediterranean varieties. Our results relate to these changing environmental conditions. Today, in a were examined in light of the diversification process founded context of global changes associated with the emergence of pests on farmer selection within traditional agroecosystems probably that threaten olive cropping, especially in southern Europe (e.g. hampered by frequent climatic accidents such as frost. Xylella fastidiosa), there is call for the selection of varieties adapted to new environmental conditions (De Ollas et al., 2019). The characterization of olive varieties in any germplasm bank and the MATERIAL AND METHODS elucidation of their origins are thus high priority to ensure efficient Plant Material use of genetic resources in the future. The FOGB includes a total of 113 olive accessions, and is In France, olive is traditionally cultivated in southern regions maintained on the island of Porquerolles, near Toulon in southern on the rim of the Mediterranean Sea. Major development of olive France (Table 1). These accessions are identified with a variety cultivation was initiated by Phoenicians in Massalia, i.e. present name and/or with tree coordinates in the collection (Table 1). day Marseille, around 2600 BP, while wild olives were already Among the 63 accessions identified with a variety name, 14 are present and some local varieties were also likely cultivated (Terral considered as being the main French varieties since they are et al., 2004). More than 100 French olive varieties are currently cropped over broad areas compared to minor varieties (22), which described based on morphological descriptors (Moutier et al., have a limited distribution range, generally over a few townships, 2004; Moutier et al., 2011) and molecular markers (Khadari and to local varieties (27), which are only present in one or two et al., 2003; Khadari et al., 2004).