L’oléiculture au Maroc de la préhistoire à nos jours : pratiques, diversité, adaptation, usages, commerce et politiques

International audienceCe numéro propose une relecture de la place de l’oléiculture dans l’histoire de l’Ouest méditerranéen et plus particulièrement le Maroc. L’olivier y est considéré comme un modèle des relations sociales et environnementales : la distribution de la diversité génétique, les flux de gènes entre oliviers et oléastres, ou l’équilibre entre les variétés locales et les variétés étrangères sont liés aux stratégies de conservation, de sélection, d’amélioration et aux stratégies de développement et de valorisation oléicoles. La question de l’impact de la sélection variétale et de la dynamique évolutive de l’olivier constitue un axe commun aux chercheurs engagés dans différentes disciplines (écologie, biologie, génétique, ethnobiologie, archéologie, archéobotanique, histoire, agronomie, socio-économie, économie politique internationale). Leurs travaux mettent en perspective différents facteurs déterminant les dynamiques variétales, environnementales et sociales. Au début, les contributions apportent de nouveaux éléments sur la manière d’analyser et d’interpréter la diversité variétale et l’évolution de l’oléiculture depuis la préhistoire à la période contemporaine. Puis les approches de la génétique et de l'histoire interrogent la dominance de la « Picholine marocaine ». L'origine de cette variété, les facteurs historiques de sa diffusion au Maroc, son impact sur les agroécosystèmes traditionnels et sur la conception des programmes de sélection génétique y sont analysés. Afin d’approfondir les dynamiques à l’œuvre dans la diversification variétale de l’olivier, les approches de la génétique, de la socio-économie et de l’ethnobotanique, analysent l’évolution des écosystèmes et des pratiques paysannes. L’angle de l’économie politique internationale et de la socio-économie interroge alors le rôle des opérateurs privés et des organismes publics dans la diffusion variétale, en se focalisant en particulier sur les pépinières et les appellations d’origine oléicoles. Enfin, les dernières contributions présentent de nouvelles approches pour l'étude de l’olivier au Maroc. Des résultats préliminaires sur la plasticité de l’olivier, sur les caractères anatomiques de son bois et sur les données relatives au pollen y sont restitués. L’ensemble de ce travail fournit des éléments de réponse nuancés sur les facteurs déterminant la diffusion variétale et la dynamique de la diversification de l’olivier. Il ouvre de nouvelles pistes de recherche sur les mesures permettant de mieux évaluer les adaptations aux changements environnementaux et sur le rôle des politiques économiques dans la diffusion variétale

Centennial Olive trees in Lebanon: a substantial patrimony

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitièresThis study aimed to assess the centennial olive trees growing across Lebanon, with theperspective of conservation of the ancient germplasm. The survey indicated the existenceof numerous centennial olive trees distributed in different agro-climatic areas, from 80 to1350 meters altitude across the country. Centennial olives were found in large sizeorchards and scattered as well as in young orchards, road hedges and gardens forornamental purposes. Yet, no reliable information is available regarding the age of thecentennials, but they can considered as 500 to 1000 years old. Among these, only sixcentennials located in Bcheale village in the north of the country at 1000 meters altitudeare considered as “millenials” or “monumentals” by the Ministry of Tourism, while theremaining ones widespread across the countries are still ignored. As a preliminarymorphological characterization of the trees conducted on 292 centennials spread in 48orchards, a large variability was recorded for foot, trunk and central cavity sizes. Principalcomponent analysis showed that foot and trunk circumferences as well as central cavitydiameter were the most discriminating descriptors. Most of the 48 orchards were clusteredtogether in one pool sharing similar traits. The most outstanding orchards were located in10 locations distributed across Lebanon. At the tree level, six single trees located in Northand Mount Lebanon were well differentiated by their large sized foot, trunk and centralcavity diameter. These centennials should be further characterized using morphologicaland agronomical descriptors in order to understand their performance through time and tovalorize them in selection programs

Extent of the genetic diversity in Lebanese olive (Olea europaea L.) trees: a mixture of an ancient germplasm with recently introduced varieties

AGAP : équipe Génomique évolutive et gestion des populations (GE²pop)International audienceThe olive tree was primary domesticated in the North-East Levant at least six millennia ago. Nowadays monumental trees are surviving across the Mediterranean Basin. These ancient, traditional varieties testify for the long cultivation of the crop but this germplasm remains incompletely characterized. Here, we investigated the genetic diversity among Lebanese cultivated olives in comparison to accessions from the whole Mediterranean Basin. Seventy-three olive trees including six monumentals were sampled in four main Lebanese areas, and characterized with 12 nuclear microsatellites and 39 plastid DNA markers. These genetic profiles were combined to those previously obtained in the world collection of Marrakech (WOGB) and analyzed with a phenetic approach, a multivariate analysis, and a Bayesian clustering method. Three main genetic clusters were identified in the Mediterranean cultivated olive tree as previously shown. The majority of Lebanese olive trees were assigned to the Eastern Mediterranean gene pool. A few genotypes were however assigned to the Central Mediterranean cluster. Plastid DNA markers revealed the presence of four haplotypes belonging to lineages E1 (72 olive trees) and E2 (one plant). Haplotype E1.1 that originated in the Eastern Mediterranean was found in 68 individuals (93 %). Within the common variety "Baladi", several nuclear microsatellite profiles were identified including closely related olive trees that may correspond to molecular variants due to somatic variation. The six monumentals were remarkably positioned close to the Cypriot accessions and showed three different profiles, one of which matched to the most common profile of the widespread traditional variety "Baladi". Our findings suggest that the Lebanese olive trees were locally selected during the beginning stages of olive growing and served as basic plant material for the current traditional varieties derived by both sexual and clonal propagation. Recent variety introductions from westernmost regions were also evidenced, but only in modern orchards from the Bekaa district

Genetic Mapping and Detection of Quantitative Trait Loci

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitièresOlive tree is a long-living woody species with similar genomic and phenotypic constraints to other perennial fruit crops. However, compared to apple, grape, and peach, genomic investigations for designing innovative breeding strategies are still limited to only preliminary research in this species. In this chapter, we aim to describe the studies on genetic mapping and underline the most promising investigations and initiatives to build a Mediterranean network suitable for establishing robust marker-trait associations through QTL mapping and association studies. These tools should serve to finally implement new breeding programs driven by marker-assisted breeding