Genetic structure and core collection of the World Olive Germplasm Bank of Marrakech: towards the optimised management and use of Mediterranean olive genetic resources

The conservation of cultivated plants in ex-situ collections is essential for the optimal management and use of their genetic resources. For the olive tree, two world germplasm banks (OWGB) are presently established, in Córdoba (Spain) and Marrakech (Morocco). This latter was recently founded and includes 561 accessions from 14 Mediterranean countries. Using 12 nuclear microsatellites (SSRs) and three chloroplast DNA markers, this collection was characterised to examine the structure of the genetic diversity and propose a set of olive accessions encompassing the whole Mediterranean allelic diversity range. We identified 505 SSR profiles based on a total of 210 alleles. Based on these markers, the genetic diversity was similar to that of cultivars and wild olives which were previously characterised in another study indicating that OWGB Marrakech is representative of Mediterranean olive germplasm. Using a model-based Bayesian clustering method and principal components analysis, this OWGB was structured into three main gene pools corresponding to eastern, central and western parts of the Mediterranean Basin. We proposed 10 cores of 67 accessions capturing all detected alleles and 10 cores of 58 accessions capturing the 186 alleles observed more than once. In each of the 10 cores, a set of 40 accessions was identical, whereas the remaining accessions were different, indicating the need to include complementary criteria such as phenotypic adaptive and agronomic traits. Our study generated a molecular database for the entire OWGB Marrakech that may be used to optimise a strategy for the management of olive genetic resources and their use for subsequent genetic and genomic olive breeding

Effects of a Composite Endomycorrhizal Inoculum on Olive Cuttings under the Greenhouse Conditions

This study was carried out in a nursery to evaluate the impact of mycorrhizal fungi on the cutting's root growth, and root colonization of a Moroccan olive variety ‘Picholine Marocaine' under greenhouse conditions during 2 years of cultivation. The results revealed that the inoculation with a composite inoculum of arbuscular mycorrhizal fungi (AMF) stimulated an early root formation and high development of vegetative shoots in inoculated cuttings respectively, 35 days (50 days in the control plots) and 40 days (60 days in the control plots) after their culture. The progressive establishment of mycorrhizal symbiosis in the roots of the inoculated plants showed that the root and vegetative masses were respectively 24 g and 19.5 g two years after inoculation. The average height and the leave's number of the inoculated plants relative to the control were respectively s 42/ 12 cm and 145/12. The newly formed roots were mycorrhizal and present different structures characteristic of AMF: arbuscules, vesicles, hyphae and spores, whose frequency and intensity reached 90% and 75% two years after cuttings cultivation. The arbuscular and vesicular contents and the number of spores were 67%, 96% and 212 spores/ 100 g of soil respectively. The fourteen species of mycorrhizal fungi isolated from the rhizosphere belong to 4 genera (Glomus, Acaulospora, Gigaspora, and Scutellospora) and three families (Glomaceae, Acaulosporaceae and Gigasporacea).The Glomus genus was the most dominant (65%) followed by the Gigaspora genus (22%). Glomus intraradices, Gigaspora sp.2, Glomus versiformes are the most abundant species, their frequency of occurrence are respectively 30%, 21% and 16%

Plasticity of fruit and oil traits in olive among diferent environments

Olive is a long-living perennial species with a wide geographical distribution, showing a large genetic and phenotypic variation in its growing area. There is an urgent need to uncover how olive phenotypic traits and plasticity can change regardless of the genetic background. A two-year study was conducted, based on the analysis of fruit and oil traits of 113 cultivars from fve germplasm collections established in Mediterranean Basin countries and Argentina. Fruit and oil traits plasticity, broad‐sense heritability and genotype by environment interaction were estimated. From variance and heritability analyses, it was shown that fruit fresh weight was mainly under genetic control, whereas oleic/(palmitic+linoleic) acids ratio was regulated by the environment and genotype by environment interaction had the major efect on oil content. Among the studied cultivars, diferent level of stability was observed, which allowed ranking the cultivars based on their plasticity for oil traits. High thermal amplitude, the diference of low and high year values of temperature, negatively afected the oil content and the oleic acid percentage. Information derived from this work will help to direct the selection of cultivars with the highest global ftness averaged over the environments rather than the highest ftness in each environment separately.EEA San JuanFil: Mousavi, Soraya. Consiglio Nazionale delle Ricerche. Institute of Biosciences and Bioresources; ItaliaFil: Mousavi, Soraya. Consiglio Nazionale delle Ricerche. Institute for Agricultural and Forest Systems of the Mediterranean; ItaliaFil: De la Rosa, Raúl. Instituto Andaluz de Investigación y Formación Agraria, Pesquera, Alimentaria y de la Producción Ecológica (IFAPA). - Centro Alameda del Obispo; EspañaFil: Moukhli, Abdelmajid. Institut National de la Recherche Agronomique (INRA). Centre Régional de la Recherche Agronomique( CRRA); MarruecosFil: El Riachy, Milad. Lebanese Agricultural Research Institute (LARI); LíbanoFil: Mariotti, Roberto. Consiglio Nazionale delle Ricerche. Institute of Biosciences and Bioresources; ItaliaFil: Torres, Myriam Mariela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Juan; Argentina.Fil: Torres, Myriam Mariela. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pierantozzi, Pierluigi. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Juan; Argentina.Fil: Pierantozzi, Pierluigi. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Stanzione, Vitale. Consiglio Nazionale delle Ricerche. Institute for Agricultural and Forest Systems of the Mediterranean; ItaliaFil: Mastio, Valerio. Consiglio Nazionale delle Ricerche. Institute for Agricultural and Forest Systems of the Mediterranean; ItaliaFil: Zaher, Hayat. Institut National de la Recherche Agronomique (INRA). Centre Régional de la Recherche Agronomique; MarruecosFil: El Antari, Abderraouf. Institut National de la Recherche Agronomique (INRA). Centre Régional de la Recherche Agronomique; MarruecosFil: Ayoub, Salam. National Agricultural Research Center (NARC); JordaniaFil: Dandachi, Faten. Lebanese Agricultural Research Institute (LARI); LíbanoFil: Youssef, Hiyam. Lebanese Agricultural Research Institute (LARI); LíbanoFil: Aggelou, Nikolas. Mediterranean Agronomic Institute of Chania (MAICh). Department of Horticultural Genetics and Biotechnology; GreciaFil: Contreras Valetín, Ana Cibeles. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria San Juan; Argentina.Fil: Contreras Valetín, Ana Cibeles. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Maestri, Damián. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal (IMBV); ArgentinaFil: Maestri, Damián. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Belaj, Angjelina. Instituto Andaluz de Investigación y Formación Agraria, Pesquera, Alimentaria y de la Producción Ecológica (IFAPA). - Centro Alameda del Obispo; EspañaFil: Bufacchi, Marina. Consiglio Nazionale delle Ricerche. Institute for Agricultural and Forest Systems of the Mediterranean; ItaliaFil: Baldoni, Luciana. Consiglio Nazionale delle Ricerche. Institute of Biosciences and Bioresources; ItaliaFil: León, Lorenzo. Instituto Andaluz de Investigación y Formación Agraria, Pesquera, Alimentaria y de la Producción Ecológica (IFAPA). - Centro Alameda del Obispo; Españ

Ongoing domestication and diversification in grafted olive-oleaster agroecosystems in Northern Morocco

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitièresThis paper analyzes sociohistorical and biological factors that shape olive-oleaster agroecosystems (hereafter OOAs), in northern Morocco and their continuing roles in olive domestication, diversification and food security. Forests are cleared and oleasters (wild olive trees) are preserved by farmers for their valuable oil and for use as rootstocks to graft olive. This practice is among those that have shaped olive domestication in the Mediterranean region. It contributes to the creation of forest-based olive agroecosystems and favors olive intraspecific diversity that is highly adapted to heterogeneous mountain environments. Productions contribute to food security, short trade circuits, land tenure and cultural identity. Ethnobiological studies show a continuity of classification, naming and uses between selected oleaster types and olive varieties suggesting an ongoing domestication process. This is supported by genetic analyses which show a higher concentration of genotypes selected from seedlings that propagate through sexual propagation in OOAs as compared to areas where management of oleasters for oil and as rootstocks is absent. Photointerpretation of aerial images corroborated with field-based observations, show the impacts of exogenous projects since the French and Spanish Protectorate periods to contemporary projects of the state policy "Plan Maroc Vert." We discuss the importance of OOAs for the preservation of on-farm genetic resources, food security and as models for future agroecosystems within the context of climate change

Role of Phenolic Metabolism in the Defense of the Olive-tree against Leaf-spot Disease Caused by Spilocaea oleaginae

International audienceIn order to study the role of phenolic metabolism in the defense of the olive-tree against Spilocaea oleagina, three defense components: soluble phenols, parietal phenols, lignin and phenylalanine ammonia-lyase (PAL), were studied in two different varieties: a resistant (Picholine du Languedoc) and a susceptible (Moroccan Picholine). The inoculation of olive-tree leaves by Spilocaea oleagina induces a foliar necrosis whose speed of onset and expansion distinguishes clearly the two studied varieties according to their behaviour to the leaf-spot disease. For the resistant variety, these symptoms are composed of small necrotic lesions, whereas for the susceptible variety, they appear as extended necrotic spots. These symptoms are accompanied by an increase in the accumulation of the contents of soluble and parietal phenols, the intensification of the lignification and the induction of the PAL activity of which the speed and intensity plainly distinguish both varieties under study. These results reveal that the response of phenolic metabolism to the resistance of the olive tree to the leaf-spot disease appears to occur in the early stages of infection leading to an increase in the biosynthesis of the contents of three defense components (soluble phenols, parietal phenols and lignin). (c) 2013 Friends Science Publisher

Menara gardens: a Moroccan olive germplasm collection identified by a SSR locus-based genetic study

UMR DAP, équipe AFEF Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienceThe Menara gardens in Marrakech (Morocco), established in the 12th century, comprise more than 2000 olive trees. To assess the genetic diversity within these gardens, we performed SSR analysis of 128 randomly sampled olive trees. Using 15 SSR loci which revealed 70 alleles, we identified 16 distinct genotypes. The analysis of chloroplast DNA polymorphism allowed to identify 2 chlorotypes: COM1 for 2 genotypes and CE1 for all others. Among the 128 trees analysed, Picholine marocaine was the prevalent cultivar represented by 100 trees (78%), the 28 remaining trees being classified into 15 distinct genotypes. However, four genotypes were closely related to Picholine marocaine from which they probably derived through somatic mutations. The genotypic and genetic diversity observed in Menara gardens compared with the genotype diversity from different areas (North and Atlas); these facts support the hypothesis that these gardens have been planted with trees probably originating from different areas of Morocco. Our results point out an important concept for ex situ conservation: the assumption that local Moroccan olive germplasm was empirically, but not purposively, conserved already in Menara garden

Resistance of olive tree to Spilocaea oleagina is mediated by the synthesis of phenolic compounds

E-mail Addresses: [email protected] Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienceTo understand the resistance of the olive tree to the leaf-spot disease caused by Spilocaea oleagina, the constitutive and postinfectional synthesis phenolic compounds of the leaves were analyzed by HPLC in 110 genotypes F1 (susceptible cultivar “Picholine marocaine” x resistant cultivar “Picholine du Languedoc”) presenting of the differential behaviours to this disease (highly resistant, resistant, intermediate, susceptible & highly susceptible genotypes). The HPLC analysis distinguished 15 majors phenolic compounds according to their chromatographic and spectral characteristics into five phenolic families (hydroxycinnamic derivatives, flavonoids, verbascoside derivatives, tyrosol derivatives, oleuropein derivatives). No qualitative difference was observed between cultivars. Principal components analysis (PCA) highlighted three multifactorial components distinguishing the various genotypes according to their behaviour to the disease. These components were determined by the postinfectional contents of oleuropein and rutin and by the constitutive contents of tyrosol and its derivatives. The tyrosol and its derivatives were associated with constitutive resistance, whereas the oleuropein and rutin were associated with induced resistance. These results suggest that the activity ratio of the enzymes implied in various biosynthesis ways of these phenolic compounds and/or the expression rate of the corresponding genes would be at the origin of the resistance degree of olive tree to S. oleagina

Adaptation of Mediterranean fruit tree cultivation to climate change

International audienc

Construction of core collections suitable for association mapping to optimize use of Mediterranean olive (Olea europaea L.) genetic resources.

Phenotypic characterisation of germplasm collections is a decisive step towards association mapping analyses, but it is particularly expensive and tedious for woody perennial plant species. Characterisation could be more efficient if focused on a reasonably sized subset of accessions, or so-called core collection (CC), reflecting the geographic origin and variability of the germplasm. The questions that arise concern the sample size to use and genetic parameters that should be optimized in a core collection to make it suitable for association mapping. Here we investigated these questions in olive (Olea europaea L.), a perennial fruit species. By testing different sampling methods and sizes in a worldwide olive germplasm bank (OWGB Marrakech, Morocco) containing 502 unique genotypes characterized by nuclear and plastid loci, a two-step sampling method was proposed. The Shannon-Weaver diversity index was found to be the best criterion to be maximized in the first step using the Core Hunter program. A primary core collection of 50 entries (CC50) was defined that captured more than 80% of the diversity. This latter was subsequently used as a kernel with the Mstrat program to capture the remaining diversity. 200 core collections of 94 entries (CC94) were thus built for flexibility in the choice of varieties to be studied. Most entries of both core collections (CC50 and CC94) were revealed to be unrelated due to the low kinship coefficient, whereas a genetic structure spanning the eastern and western/central Mediterranean regions was noted. Linkage disequilibrium was observed in CC94 which was mainly explained by a genetic structure effect as noted for OWGB Marrakech. Since they reflect the geographic origin and diversity of olive germplasm and are of reasonable size, both core collections will be of major interest to develop long-term association studies and thus enhance genomic selection in olive species