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Le palmier rônier ou Borassus aethiopum Mart. est une plante aux multiples usages, qui présente des caractéristiques socio-économiques importantes pour les populations locales. Les nombreux avantages dont offre la plante, font qu'elle subit de grandes pressions anthropiques. Dans le but de définir des stratégies de gestion et de conservation à moyen et long terme, une analyse de la diversité a été effectuée grâce aux marqueurs microsatellites spécifiques de l'espèce. Ces derniers ont été développés à partir d'un séquençage partiel du génome de B. aethiopum, puis par la méthode QDD, onze (11) amorces spécifiques ont pu être définies et testées sur 180 échantillons représentant neuf (9) populations au Bénin. L'utilisation de ces marqueurs a permis de distinguer deux groupes génétiques dont l'un est constitué des populations Sud et Centre Bénin et le second groupe représentant l'ensemble des populations du Nord y compris la population de Savè qui est aussi située au Centre Bénin. De plus, dans le souci d'élucider la frontière génétique entre les différentes espèces de Borassus sp., les analyses phylogénétiques conduites sur l'ensemble des échantillons issus des cinq espèces (B. aethiopum, B. akeassii, B. madagascariensis, B. heineaus, B. flabellifer) ont permis de déterminer que l'espèce soeur de B. aethiopum serait B. madagascariensis avec une spéciation intervenue il y a trois (03) millions d'années (Ma). Ces résultats sont d'une grande importance et amélioreront l'état des connaissances aussi bien sur B. aethiopum que les autres espèces. Tout ceci contribuera à une meilleure gestion de l'espèce dans son aire de distribution.

The African fan palm Borassus aethiopum Mart. is widely distributed in savanna ecosystems throughout of the continent. It is an important non-timber forest product with multiple usages of significant socio-economic importance for local populations. As such, it is under strong anthropogenic pressures that have the potential to affect negatively the genetic diversity of the species. However, in spite of its role for fighting both desertification and poverty, the African fan palm remains under-studied, which hampers its sustainable development as a resource. In the present study, we analyze the genetic diversity and population structure of B. aethiopum sampled in different locations across Benin, West Africa. In order to achieve this, we have generated a partial, low-cover genomic sequencing of this species, using a high-throughput sequencing technology, and used it to identify microsatellite loci in the fan palm genome. Among these potential target loci, 11 were found to yield polymorphic amplifications between our test samples and were subsequently used in our analyses. Our results highlight the overall low genetic diversity of Borassus aethiopum populations in Benin, with number of effective alleles ranging from one point forty-four to two point zero sixty-nine per locus, and expected heterozygosity (He) ranging from zero point two hundred and sisty-three to zero point four hundred and fifty-one depending on the population. Moreover, our Bayesian analysis shows that Beninese fan palm populations are mostly structured according to geographic distances, with two population cluster including samples from the Southern and Central geo-climatic regions vs. samples from the Northern region, respectively. The present work constitutes a first step towards larger-scale genetic studies dedicated to B. aethiopum and, beyond that, provides new molecular data to the palm community.

Borassus aethiopum Mart. (Arecaceae, Coryphoideae) is a dioecious tree (Fig. 1) endemic to Africa which is widely distributed in savannah regions of the continent (Fig. 2). It is a multipurpose palm playing a prominent socio-economic role in local population (Fig. 3). In Benin, the hypocotyls are exploited for human diet resulting in an intense pressure on natural stands of the species with consequences on regeneration. The lack of information on seed germination and conservation hinders seedling production for sustainable Borassus aethiopum population management. In this context, we have undertaken to first describe the morpho/anatomy and germination behaviour of mature seeds, for the purpose of later addressing the physiological aspects of seed conservation.

International audience; BACKGROUND: A cryopreservation protocol has been established for oil palm somatic embryos (SEs), the efficiency of which must be evaluated, both in terms of regeneration and of long-term storage capacity, before its large-scale routine use.Objective: To test the survival and recovery of 29 clones of oil palm somatic embryos cryostored for 20 years.Materials and methods: Clumps of SEs were pregrown for 7 days on medium containing 0.75 M sucrose, dehydrated in air-tight containers containing silica gel to moisture contents between 19-35% fresh weight, and then immersed directly in liquid nitrogen and stored in cryotanks for 20 years.Results: Survival of SEs cryopreserved and rewarmed immediately displayed an average value of 19.1% for the 29 clones tested while survival of SEs rewarmed after 20 years of cryostorage was significantly higher, with an average of 33.2% for the 28 surviving clones. Out of these 28 surviving clones, three were lost due to contamination or regrowth decline, six produced only shoots and the rest proliferated.Conclusion: It is possible to cryostore oil palm SEs for extended periods and to regenerate proliferating cultures and plantlets from the cryopreserved material. The cryopreservation protocol established can thus be efficiently used to store oil palm germplasm and to manage large-scale production in industrial laboratories.

The African fan palm or toddy palm (Borassus aethiopum Mart.) plays a significant role in rural village economy because of the many uses of different parts of the plant for food, construction, traditional medicines and crafts. However, some of these uses which specifically target either male individuals (construction beams) or reproductive stages (fruits and hypocotyls) put pressure on the genetic diversity of palm populations and threaten the species as a whole. As a preliminary step to defining conservation strategies for Borassus aethiopum populations in Benin, an assessment of their genetic diversity was conducted through the use of microsatellite markers. In the absence of molecular resources for this species, we first set out to evaluate the transferability of microsatellite primers that had previously been designed in other palm species, including the cousin species from Asia Borassus flabellifer. We show that the portability of such markers, quantified as their ability to successfully amplify B. aethiopum DNA, is very low. Moreover, among the successfully transferred primers we found that the ability to detect polymorphisms, both within or among nine fan palm populations sampled across the Beninese territory, was even lower. In light of these first results, we discuss experimental options that will allow us to overcome this technical difficulty, and the future development of our project throughout the West African subregion.