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The kola tree (Cola nitida) belongs to family Malvaceae grown mainly for its seed. It is highly prized for its socio-cultural and industrial uses. However, there is a significant high variability due to a high proportion of allogamy in the reproduction mode. The influence of substrate and genotype on kola tree cuttings has been studied in order to propagate it vegetatively. Six growing substrates: 100% Black soil, 50% Black soil + 50% Wood sawdust, 100% Wood sawdust, 50% Soil + 50% Black-Coco, 100% Black-Coco, 50% Wood sawdust + 50% Black-Coco were tested on genotypes 305 and D9L7A1 using a split-plot experimental design with genotype as main factor and substrate as subplot treatment replicated three times. The experimental unit constituted 20 cuttings. Six months after transplanting, the average success rate of tunnel cutting from the kola tree to the nursery was 76.2±7.6%. The best success rates were obtained with 100% Wood sawdust, 100% Black soil and 50% Black coco + 50% Wood sawdust substrates with 85±4.5, 80.8±6.6 and 79.7±5.8%, respectively, regardless of the plant material used. The substrates 100% Black soil and 100% Wood sawdust gave the best results on growth parameters such as aerial dry biomass, height growth, roots number and new formed leaves. It also showed that genotype D9L7A1 had a higher vegetative leaves and roots development than genotype 305. These genotypes were well suited for cutting. Key words: Cola nitida, cuttings, genotype, substrate.

La maladie du balai de sorcière du colatier est la maladie la plus importante du colatier car elle engendre d’énormes pertes de production. L’objectif principal de cette étude était d’identifier des clones de colatiers d’origine ivoirienne qui affichent le meilleur profil de tolérance à la maladie du balai de sorcière et ayant des paramètres de rendement intéressants. Pour atteindre cet objectif, un dispositif expérimental en bloc complètement randomisé à 3 répétitions a été utilisé et le facteur étudié est le clone avec 13 modalités. Les résultats obtenus montrent que 5 clones (clones 305, 314, 318, A2 et A3) n’ont pas subi d’attaque de la maladie. Les clones 311, 313, 315, 321 et 322 ont été moyennement attaqués. Sur la base des paramètres de rendement tels que le poids des noix par follicule et le nombre de noix par follicule, les clones 313 et 323 ont produit les plus grosses noix dont le poids moyen varie entre 31,98±11,60 g et 34,97±8,54 g et le clone 316 a donné un plus grand nombre de noix par follicule (en moyenne, 10,63±1,55 noix par follicules). Une classification combinant le niveau de tolérance des clones et les paramètres de rendement étudiés ont permis d’identifier les clones 313, 322 et 323 comme étant les meilleurs.Mots clés : Maladie du balai de sorcière, colatier, pertes de production, rendement.

Wild genetic resources and their ability to adapt to environmental change are critically important in light of the projected climate change, while constituting the foundation of agricultural sustainability. To address the expected negative effects of climate change on Robusta coffee trees (Coffea canephora), collecting missions were conducted to explore its current native distribution in Uganda over a broad climatic range. Wild material from seven forests could thus be collected. We used 19 microsatellite (SSR) markers to assess genetic diversity and structure of this material as well as material from twoex-situcollections and a feral population. The UgandanC.canephoradiversity was then positioned relative to the species’ global diversity structure. Twenty-two climatic variables were used to explore variations in climatic zones across the sampled forests. Overall, Uganda’s nativeC.canephoradiversity differs from other known genetic groups of this species. In northwestern (NW) Uganda, four distinct genetic clusters were distinguished being from Zoka, Budongo, Itwara and Kibale forests A large southern-central (SC) cluster included Malabigambo, Mabira, and Kalangala forest accessions, as well as feral and cultivated accessions, suggesting similarity in genetic origin and strong gene flow between wild and cultivated compartments. We also confirmed the introduction of Congolese varieties into the SC region where most Robusta coffee production takes place. Identified populations occurred in divergent environmental conditions and 12 environmental variables significantly explained 16.3% of the total allelic variation across populations. The substantial genetic variation within and between Ugandan populations with different climatic envelopes might contain adaptive diversity to cope with climate change. The accessions that we collected have substantially enriched the diversity hosted in the Ugandan collections and thus contribute toex situconservation of this vital genetic resource. However, there is an urgent need to develop strategies to enhance complementaryin-situconservation ofCoffea canephorain native forests in northwestern Uganda.

International audience; Coffee species such as Coffea canephora P. (Robusta) and C. arabica L. (Arabica) are important cash crops in tropical regions around the world. C. arabica is an allotetraploid (2n = 4x = 44) originating from a hybridization event of the two diploid species C. canephora and C. eugenioides (2n = 2x = 22). Interestingly, these progenitor species harbour a greater level of genetic variability and are an important source of genes to broaden the narrow Arabica genetic base. Here, we describe the development, evaluation and use of a single-nucleotide polymorphism (SNP) array for coffee trees. A total of 8580 unique and informative SNPs were selected from C. canephora and C. arabica sequencing data, with 40% of the SNP located in annotated genes. In particular, this array contains 227 markers associated to 149 genes and traits of agronomic importance. Among these, 7065 SNPs (~82.3%) were scorable and evenly distributed over the genome with a mean distance of 54.4 Kb between markers. With this array, we improved the Robusta high-density genetic map by adding 1307 SNP markers, whereas 945 SNPs were found segregating in the Arabica mapping progeny. A panel of C. canephora accessions was successfully discriminated and over 70% of the SNP markers were transferable across the three species. Furthermore, the canephora-derived subgenome of C. arabica was shown to be more closely related to C. canephora accessions from northern Uganda than to other current populations. These validated SNP markers and high-density genetic maps will be useful to molecular genetics and for innovative approaches in coffee breeding.

The management of diversity for conservation and breeding is of great importance for all plant species and is particularly true in perennial species, such as the coffee Coffea canephora. This species exhibits a large genetic and phenotypic diversity with six different diversity groups. Large field collections are available in the Ivory Coast, Uganda and other Asian, American and African countries but are very expensive and time consuming to establish and maintain in large areas. We propose to improve coffee germplasm management through the construction of genetic core collections derived from a set of 565 accessions that are characterized with 13 microsatellite markers. Core collections of 12, 24 and 48 accessions were defined using two methods aimed to maximize the allelic diversity (Maximization strategy) or genetic distance (Maximum- Length Sub-Tree method). A composite core collection of 77 accessions is proposed for both objectives of an optimal management of diversity and breeding. This core collection presents a gene diversity value of 0.8 and exhibits the totality of the major alleles (i.e., 184) that are present in the initial set. The seven proposed core collections constitute a valuable tool for diversity management and a foundation for breeding programs. The use of these collections for collection management in research centers and breeding perspectives for coffee improvement are discussed.

International audience; The frequency of plant species introductions has increased in a highly connected world, modifying species distribution patterns to include areas outside their natural ranges. These introductions provide the opportunity to gain new insight into the importance of flowering phenology as a component of adaptation to a new environment. Three Coffea species, C. arabica, C. canephora (Robusta), and C. liberica, native to intertropical Africa have been introduced to New Caledonia. On this archipelago, a secondary contact zone has been characterized where these species coexist, persist, and hybridize spontaneously. We investigated the impact of environmental changes undergone by each species following its introduction in New Caledonia on flowering phenology and overcoming reproductive barriers between sister species. We developed species distribution models and compared both environmental envelopes and climatic niches between native and introduced hybrid zones. Flowering phenology was monitored in a population in the hybrid zone along with temperature and precipitation sequences recorded at a nearby weather station. The extent and nature of hybridization events were characterized using chloroplast and nuclear microsatellite markers. The three Coffea species encountered weak environmental suitability compared to their native ranges when introduced to New Caledonia, especially C. arabica and C. canephora. The niche of the New Caledonia hybrid zone was significantly different from all three species' native niches based on identity tests (I Similarity and D Schoener's Similarity Indexes). This area appeared to exhibit intermediate conditions between the native conditions of the three species for temperature-related variables and divergent conditions for precipitation-related ones. Flowering pattern in these Coffea species was shown to have a strong genetic component that determined the time between the triggering rain and anthesis (flower opening), specific to each species. However, a precipitation regime different from those in Africa was directly involved in generating partial flowering overlap between species and thus in allowing hybridization and interspecific gene flow. Interspecific hybrids accounted for 4% of the mature individuals in the sympatric population and occurred between each pair of species with various level of introgression. Adaptation to new environmental conditions following introduction of Coffea species to New Caledonia has resulted in a secondary contact between three related species, which would not have happened in their native ranges, leading to hybridization and gene flow.

Rubber has been grown for several decades in Africa, notably in Ivory Coast. Although the yields obtained with selected clones are good, some problems with adaptation to edaphic and climatic conditions have yet to be solved. Of these problems, tree breakage due to violent winds during frequent storms is a major handicap. Some clones are more resistant to wind damage. However, this resistance trait remains difficult to measure, and detecting it at an early stage appeared important. As no differences have been found in the physical properties of the wood of different clones, the search for differences between clones displaying resistance and susceptibility to wind damage was switched to architectural structures. Architectural traits were thus studied on two rubber clones with very different resistances to wind. Observations were focused both on young trees and adult trees. Of all the architectural traits observed, a description of branching provided information likely to explain differences in the way the clones being studied developed over time. The clone GT1 which is resistant to wind, developed more lateral branches but they did not grow much in length. On the other hand, fewer axillary branches appeared on the susceptible clone PB235 but they grew longer. Moreover, as some of these traits proved to be similar in both young and adult trees, they could be detected at a sufficiently early stage for use as early prediction traits, if their involvement in susceptibility to wind damage is confirmed.

The first genetic map for Hevea spp. (2n=36) is presented here. It is based on a F, progeny of 106 individuals allowing the construction of a female, a male, and a synthetic map according to the pseudo-testcross strategy. Progeny were derived from an interspecific cross between PB260, a H. brasiliensis cultivated clone, and RO38, a H. brasiliensis xH. benthamiana interspecific hybrid clone. The disomic inheritance observed for all the codominant markers scattered on the 2n=36 chromosomes revealed that Hevea behaves as diploids. Homologous linkage groups between the two parental maps were merged using bridge loci. A total of 717 loci constituted the synthetic map, including 301 RFLPs, 388 AFLPs, 18 microsatellites, and 10 isozymes. The markers were assembled into 18 linkage groups, thus reflecting the basic chromosome number, and covered a total distance of 2144 cM. Nine markers were found to be unlinked. Segregation distortion was rare (1.4%). Average marker density was 1 per 3 cM. -Comparison of-die distance between loci in the parental maps revealed significantly less meiotic recombination in the interspecific hybrid male parent than in the female parent. Hevea origin and genome organisation are discussed.

Background A reciprocal recurrent selection program has been under way for the Coffea canephora coffee tree for approximately thirty years in the Ivory Coast. Association genetics would help to speed up this program by more rapidly selecting zones of interest in the genome. However, prior to any such studies, the linkage disequilibrium (LD) needs to be assessed between the markers on the genome. These data are essential for guiding association studies. Results This article describes the first results of an LD assessment in a coffee tree species. Guinean and Congolese breeding populations of C. canephora have been used for this work, with the goal of identifying ways of using these populations in association genetics. We identified changes in the LD along the genome within the different C. canephora diversity groups. In the different diversity groups studied, the LD was variable. Some diversity groups displayed disequilibria over long distances (up to 25 cM), whereas others had disequilibria not exceeding 1 cM. We also discovered a fine structure within the Guinean group. Conclusions Given these results, association studies can be used within the species C. canephora. The coffee recurrent selection scheme being implemented in the Ivory Coast can thus be optimized. Lastly, our results could be used to improve C. arabica because one of its parents is closely related to C. canephora.

Coffea canephora breeding requires combining sustainable productivity with improved technological and cup quality characteristics. Beverage quality is a complex and subjective trait, and breeding for this trait is time consuming and depends on knowledge of the genetics of its components. A highly variable C. canephora progeny resulting from an intraspecific cross was assessed for 63 traits over 5 years. To identify quantitative trait loci (QTLs) controlling agronomic, technological, and quality-related traits, a genetic map comprising 236 molecular markers was constructed, and composite interval mapping was performed. Beverage quality was evaluated in relation to biochemical and cup tasting traits. QTLs were identified for almost half of the traits evaluated, with effects ranging from 6% to 80% of phenotypic variation. Most of them present a consistent detection over years. The strongest QTLs explained a high percentage of the variation for yield in 2006 (34% to 57%), bean size (25% to 35%), content of chlorogenic acids (22% to 35%), sucrose and trigonelline content (29% to 81%), and acidity and bitterness of coffee beverages (30% to 55%). Regions of the C. canephora genome influencing beverage quality were identified. Five QTL zones were co-localized with candidate genes related to the biosynthesis of the analyzed traits: two genes coding for caffeine biosynthesis, one gene implicated in the biosynthesis of chlorogenic acids, and two genes implicated in sugar metabolism. This is one of the first studies on the identification of QTLs combining agronomic and quality traits in coffee. The high variability of quality traits within C. canephora and the presence of consistent QTLs offer breeders a promising tool to improve coffee cup quality.

International audience; Coffea canephora Pierre breeding in Cote d'Ivoire is based on indirect reciprocal recurrent selection (RRSi) using the Congolese and Guinean populations. In practice, the genotypes of each population (78 Congolese genotypes and 100 Guinean genotypes) are tested with several testers from the reciprocal population: two Guinean and three Congolese testers. These testers are heterozygous as C. canephora is a strictly outcrossing species. After a first cycle of RRSi, we judged the efficiency of these testers for yield, susceptibility to coffee leaf rust (SCLR) and hundred bean weight (HBW). All the testers discriminated the tested genotypes highly significantly (P < 0.01), even though differences were found in the degrees of discrimination. For yield and SCLR, no interaction between tested genotypes and testers was observed and correlations between test values obtained from different testers were significant or highly significant. Furthermore, test values of tested genotypes could be used to predict the yield and SCLR of between-population (BP) hybrids. Prediction was always more accurate with the best tester than with the mean of several testers. As opposed to yield and SCLR, HBW showed significant interactions between tested genotypes and testers and HBW of hybrids could not be predicted from the test value of the genotypes. We conclude that only one reciprocal tester can be used in the next cycles of RRSi applied to C. canephora. This will allow either a reduced cost of selection or increased selection intensity.

Ce chapitre fait le point des connaissances actuelles sur l'organisation de la diversité de l'hévéa. Il se fonde sur les acquis d'études antérieures et présente des résultats complémentaires issus d'analyses isoenzymatiques sur un plus grand nombre de génotypes. Ces données supplémentaires ont permis de développer une démarche originale de comparaison entre variabilité morphoagronomique et diversité génétique de marqueurs neutres par une analyse factorielle multiple. Une forte corrélation a été trouvée entre les différents outils moléculaires mais chaque marqueur moléculaire apporte des informations spécifiques. Certaines différenciations entre groupes n'ont été clairement révélées que par les isoenzymes ou les RFLP. Il est intéressant de noter l'existence d'une relation entre diversité moléculaire et variabilité agronomique chez l'hévéa. La différenciation des populations d'hévéa est assez forte pour toucher l'ensemble des génomes et concerne un grand nombre de gènes, qu'il s'agisse de marqueurs neutres ou de gènes déterminant des caractères phénotypiques. En conséquence, dans l'état actuel des connaissances, la prise en compte de la structuration d'#Hevea brasiliensis# en six groupes génétiques sera très utile pour définir une stratégie d'échantillonnage de la diversité génétique de cette espèce

La stratégie PCSS (Principal Component Score Strategy) est une méthode de sélection, basée sur des analyses multivariées, proposée pour constituer des "core collection" à partir de collections importantes de ressources génétiques. La méthode décrite sur des données quantitatives est adaptée ici à des données qualitatives de type moléculaire. Ces deux méthodes ont été testées pour leurs impacts sur la structure de quatre plantes tropicales : caféier, hévéa, riz et sorgho. Les résultats montrent, dans tous les cas, que l'augmentation des contributions relatives cumulées (CRC) sont très rapides mais diffèrent d'une espèce à l'autre. Dix pour cent de la collection totale permet d'obtenir de 22 à 58% de CRC. Comme prévu, la variabilité des caractères quantitatifs dans les échantillons, est peu ou pas modifiée lorsque la sélection est qualitative mais elle l'est fortement par une sélection quantitative. La sélection qualitative apparaît comme la plus efficace pour conserver les allèles rares et augmenter la diversité globale avec des effets limités au niveau quantitatif. L'utilisation d'espèces très différentes a permis de comparer les impacts respectifs des deux méthodes et de mettre en lumière les avantages d'une sélection combinée sur les deux types d'approches. (Résumé d'auteur)