The type II clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9... more The type II clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 system (CRISPR/Cas9) has been successfully applied to edit target genes in multiple plant species. However, it remains unknown whether this system can be used for genome editing in grape. In this study, we described genome editing and targeted gene mutation in 'Chardonnay' suspension cells and plants via the CRISPR/Cas9 system. Two single guide RNAs (sgRNAs) were designed to target distinct sites of the L-idonate dehydrogenase gene (IdnDH). CEL I endonuclease assay and sequencing results revealed the expected indel mutations at the target site, and a mutation frequency of 100% was observed in the transgenic cell mass (CM) as well as corresponding regenerated plants with expression of sgRNA1/Cas9. The majority of the detected mutations in transgenic CM were 1-bp insertions, followed by 1-to 3-nucleotide deletions. Off-target activities were also evaluated by sequencing the potential off-target sites, and no obvious off-target events were detected. Our results demonstrated that the CRISPR/Cas9 system is an efficient and specific tool for precise genome editing in grape. Targeted genome editing (TGE) using site-specific nucleases (SSNs) promises to be critical to basic and applied biology research. These powerful SSN tools, comprising zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regulatory interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system (CRISPR/Cas9), introduce targeted DNA double-strand breaks (DSBs) and subsequently trigger DNA repair pathways involving either non-homologous end-joining (NHEJ) or homologous recombination (HR) 1. Both ZFNs and TALENs, which consist of customizable ZF/TALE DNA-binding domains (DBDs) with FokI cleavage domains, have been proven successful in targeted genome modification 2-4. However, disadvantages such as the time required for designing the constructs make these two methods difficult and expensive to use 5,6. Recently, the RNA-guided CRISPR/Cas9 system has been widely used in TGE. There are three types of CRISPR/Cas9 systems (I, II and III), and the type II system with a single Cas9 protein has emerged as a simple but highly efficient tool for TGE 7,8. The Cas9 nuclease is guided by a duplex formed by CRISPR RNA (crRNA) and trans-activating crRNA (tracrRNA) which cleaves the complementary sequence of the crRNA accompanied by an NGG protospacer adjacent motif (PAM) 9,10. The PAM is indispensable for target recognition as it helps the crRNA-tracrRNA-Cas9 complex combine with the target sequence 11,12. In an engineered CRISPR/Cas9 system, the crRNA-tracrRNA duplex has been fused into an artificial single guide RNA (sgRNA) containing a 20-nucleotide (nt) sequence that determines the DNA target site 7,10,13. To date, the CRISPR/Cas9 system has been adopted for TGE successfully in many organisms, including mammalian cells 10,13 , yeast 14 , zebrafish embryos 15 , mice 16 , and numerous herbaceous plants such as Arabidopsis 17-19 , tobacco 19,20 , rice 17,21,22 , wheat 23 , maize 6 , sorghum 23 , soybean 24 , and tomato 25,26. This genome modification is heritable, and the sequence changes in the first generation of stable herbaceous plant transformants persist into the next generation 27,28. In addition, the transient expression of Cas9 and sgRNA in rice and wheat protoplasts also successfully directs genome modification 29. Nevertheless, the CRISPR/Cas9 system has rarely been reported to effectively work in perennial plants except for poplar and citrus 30,31 .
HAL (Le Centre pour la Communication Scientifique Directe), Sep 1, 2017
International audienceThe phenolic composition of aqueous extract from dried leaves of Lippia mul... more International audienceThe phenolic composition of aqueous extract from dried leaves of Lippia multiflora Moldenke was analyzed by liquid chromatography- mass spectrometry (LC-MS) before inverse solid phase fractionation. The crude extract and the different fractions (from FL1 to FL5) obtained after fractionation were then tested in vitro for their effect on two fungi responsible of peanut foliar diseases, Phaeoisariopsispersonata and Pucciniaarachidis. The chemical analysis of the aqueous L. multiflora crude extract indicated the presence of seven phenolic compounds (nuomiosideA, isonuomiside A, samioside, verbascoside, isoverbascoside, alyssonoside and leucoseptoside A) and one monoterpene (geniposide). The antifungal activity, estimated by the efficient rate of the fungal appressorium formation, varied from 33.33% to 58.33% and 5.56% to 38.89% for P. personataand P. arachidis spores, respectively. By spraying the different fractions on artificially contaminated leaves, the best antifungal activity was noticed using FL3 and FL4 fractions, the only one in which the presence of samioside was described. The results of this study suggest that the protecting effect of Lippiaextracts against peanut pathogens may be related to the presence of four phenylethanoid glucosides: verbascoside, nuomoside A, leucoseptoside A and samiosid
The coffee research community has maintained a long ongoing debate regarding the implications of ... more The coffee research community has maintained a long ongoing debate regarding the implications of shade trees in coffee production. Historically, there has been contrasting results and opinions on this matter, thus recommendations for the use of shade (namely in coffee agroforestry systems) are often deemed controversial, particularly due to potential yield declines and farmers’ income. This study is one of the first demonstrating how severalCoffea arabicacultivars respond differently to shade with respect to yield. By standardising more than 200 coffee yield data from various in-field trials, we assembled the so-called “Ristretto” data pool, a one of a kind, open-source dataset, consolidating decades of coffee yield data under shaded systems. With this standardised dataset, our meta-analysis demonstrated significant genotypic heterogeneity in response to shade, showing neutral, inverted U-shaped and decreasing trends between yield and shade cover amongst 18 different cultivars. Thes...
27th Biennial ASIC Conference, Portland, 16-20 September 2018. Book of abstracts 2019, 2019
Nowadays coffee somatic embryogenesis (SE) can be considered as a model for woody perennial crops... more Nowadays coffee somatic embryogenesis (SE) can be considered as a model for woody perennial crops as its industrial application already allowed the dissemination of 50 millions of elite plants in the two cultivated species. The process works with high biological efficiency is observed at all developmental stages and somaclonal variation is mastered. Current research beneficiates from this regeneration model as well as from the progress of coffee genomics and biotechnologies, focuses on two distinct objectives. The recent advances of this research and their respective outputs are reviewed and discussed in this presentation. The first objective is to develop basic research based on-omics methodologies to decipher the fondamental mechanisms associated to cell reprogramming by focusing on two examples: i) Taking advantage of optimized SE protocols, we will unravel totipotency mechanisms and molecular events involved in the key developmental switches occurring during cell dedifferentiation/redifferentiation. A multi approach characterization through cell imaging, massive transcriptomic, epigenetic and metabolomic analyzes is applied at all the key developmental stages from the leaf explant to torpedo-shaped embryos (7 well characterized developmental stages). Big data integration and a system biology approach will provide a thorough knowledge of the expression of totipotency. ii) Coffee embryos acquire the capacity to photosynthetize very early in their developmental process (at the cotyledonary stage). Understanding the events leading to the acquisition of photo-autotrophy is also being studied by ecophysiological and molecular approaches applied to torpedo and cotyledonary-shaped embryo cultures under contrasted light, C02 and sugar conditions. Otherwise, the second objective is to provide - through technological approaches - powerful tools to accelerate the optimization of coffee breeding: i) The high-throughput molecular screening method has been recently developed by Nestle that allows to miniaturize the SE process and opens the way to study the biological effect of new active molecules on particular developmental switches' efficiency. It will also allow the development of miniaturized EMS (Ethyl Methyl Sulphate) mutant banks by simplifying their setting up and further management. ii) The genome editing of coffee genome by the Crispr/Cas9 technology recently described by using embryogenic tissues transformation gives us the possibility to rapidly and precisely manipulate plant genomes to introduce a trait of agronomic interest
Arabica coffee is a main economic crop throughout Central and South American highlands, where mil... more Arabica coffee is a main economic crop throughout Central and South American highlands, where millions of people get primary outcome. Last coffee leaf rust (CLR) epidemic event in 2011, which impacted 53% of the coffee region areas, provoking losses up to USD 500 million, remembered the high vulnerability of the coffee sector to the fungus Hemileia vastatrix, causal agent of this disease and considered as the main restrictive illness for all coffee regions around the world. The main problem remains that the current commercial varieties reputed as "resistant", become sensitive to the CLR. During the last twenty years, coffee geneticist have created several intra-specific hybrids between commercial varieties and wild coffee accessions. Field observations confirmed that coffee hybrids are more productive and less impacted by the CLR even in regions where resistant materials become susceptible. Such field observations are in agreement with the general idea that hybrid plants p...
L'acacia au Sénégal << arbre miracle), du Sénégal, sera considéré comme faisant partie des Acacia... more L'acacia au Sénégal << arbre miracle), du Sénégal, sera considéré comme faisant partie des Acacia et sera indifféremment appelé Faidherbia albida ou Acacia albida dans l'ouvrage. Les communications sont rassemblées selon les thématiques de recherche. Chaque thème regroupe un article de synthèse des travaux dans le domaine abordé ainsi que la présentation des travaux les plus récents. La première partie fait l'état des connaissances en écologie et écophysiologie, en relation avec la contrainte hydrique, pour les espèces socio-économiquement les plus importantes dans les régions sahéliennes, et plus particulièrement A. tortilis, F: albida et A. senegal. La deuxième partie présente les différentes politiques de valorisation agroforestières des acacias réalisées au Sénégal et au Burkina Faso. La troisième partie rassemble les données existantes sur la contribution des acacias dans le cycle de l'azote, l'exposé de synthèse faisant une présentation plus générale des derniers acquis sur I'absorption du nitrate par les racines. La quatrième partie présente les expérimentations réalisées en culture in vitro. La cinquième partie est consacrée à la diversité génétique des acacias et la sixième partie regroupe les connaissances acquises sur les organismes associés aux acacias et leurs interrelations : bactéries symbiotiques fixatrices d'azote, nématodes et champignons symbiotiques. Nous espérons que cet ouvrage, pluridisciplinaire, apportera au lecteur, familier ou non de l'Acacia et des zones arides, des connaissances nouvelles sur cet arbre, même si tous les domaines ne sont pas abordés. Nous tenons à remercier les auteurs ainsi que le comité de lecture pour leur participation enthousiaste à la réalisation de cet ouvrage.
Meloidogyne paranaensis is a root-knot nematode (RKN) affecting coffee production in Latin Americ... more Meloidogyne paranaensis is a root-knot nematode (RKN) affecting coffee production in Latin America. Simultaneous histological and histochemical studies were carried out on Coffea arabica cv Caturra (susceptible), a wild Ethiopian accession of Coffea arabica (resistant ) and a rootstock Coffea canephora cv Nemaya (resistant) after inoculation with this RKN in order to characterize compounds accumulating after infection in resistant cultivars. No hypersensitive-like reaction was induced neither in C. arabica, nor in C. canephora resistant genotypes. Instead, these two resistant coffee genotypes develop the same original resistance mechanisms against M. paranaensis i.e. flavonoids accumulation into giant cells of the feeding sites induced by the RKN. Chlorogenic acids accumulating around infestation sites could act as flavonoid precursors. (Resume d'auteur)
Chemical analysis of aqueous extract of Ziziphus mucronata Willd. was determined by liquid chroma... more Chemical analysis of aqueous extract of Ziziphus mucronata Willd. was determined by liquid chromatography-mass spectrometry (LC-MS) analysis. Among the 11 compounds found, catechin, rutin (quercetin 3-O-rutinoside), delphinidin-3-glucoside, isoquercetin (hyperoside) and quercitrin (quercetine3,7-O-L-dirhanmopyranoside) were identified as the major phenolics components in this aqueous plant extract. To elute the target compounds, the fractionation of crude extract was carried out on solid phase extraction (SPE) columns. The different fractions (from FZ1 to FZ5) obtained after fractionation were evaluated in vitro against economically important foliar fungal pathogens of peanut, including Cercospora arachidicola, Phaeoisariopsis personata and Puccinia arachidis. The treatments with Z. mucronata fractions were compared with negative control (water) and standard solutions of cathechin and rutin (1 mg/mL). All the fractions recorded an inhibitory effect, firstly on conidial germination and germ tube elongation, secondly on disease evolution on peanut leaves previously inoculated by fungi; the level of efficiency of inhibition varied from 40.55 (FZ1 against C. arachidicola) to 57.14% (FZ2 and FZ3 against P. arachidis). Then, spores of P. arachidis seemed to be more sensitive to the treatment.
Background Somatic embryogenesis (SE) is one of the most promising processes for large-scale diss... more Background Somatic embryogenesis (SE) is one of the most promising processes for large-scale dissemination of elite varieties. However, for many plant species, optimizing SE protocols still relies on a trial and error approach. We report the first global scale transcriptome profiling performed at all developmental stages of SE in coffee to unravel the mechanisms that regulate cell fate and totipotency. Results RNA-seq of 48 samples (12 developmental stages x 4 biological replicates) generated 90 million high quality reads per sample, approximately 74% of which were uniquely mapped to the Arabica genome. First, the statistical analysis of transcript data clearly grouped SE developmental stages into seven important phases (Leaf, Dedifferentiation, Primary callus, Embryogenic callus, Embryogenic cell clusters, Redifferentiation and Embryo) enabling the identification of six key developmental phase switches, which are strategic for the overall biological efficiency of embryo regeneratio...
A field experiment was conducted at Bel Air station, in Dakar using 15N isotope dilution techniqu... more A field experiment was conducted at Bel Air station, in Dakar using 15N isotope dilution technique and the non nodulating soybean (Glycine max) variety m129 as reference plant to estimate nitrogen fixation in common bean (Phaseolus vulgaris). Dry matter production and nitrogen accumulation were increased in plants inoculated with Rhizobium strain ISRA 355 compared to uninoculated plants ( +31 % and +50%, respectively) and in 20 N-fertilized plants compared to non N fertilized plants ( +36% and +39%, respectively). In addition, %Ndfa was increased in common bean inoculated with strain ISRA 355 ( +32% higher than non inoculation) or supplied with 20 kg N/ha (+37% higher than non N fertilization). However, the amount of fixed nitrogen was increased by the interaction inoculation x 20 Nfertilization only ( + 155% over the value averaged across all uninoculated plants). From all treatments, estimates of fixed nitrogen were ranged between 63 to 139 kg N /ha. Beside this estimation, nitrog...
Current Plant Science and Biotechnology in Agriculture, 1998
For its contribution to soil fertility in agroforestery systems, Acacia albida Del. appears as on... more For its contribution to soil fertility in agroforestery systems, Acacia albida Del. appears as one of the most useful N2-fixing Sahelian trees. As it shows a low nitrogen fixing potential (Ndoye et al., 1995) and a great capacity to accumulate soil NO3 in its roots (unpublished), in vitro techniques were developed on young inoculated seedlings to evaluate the effect of external NO3 on nodulation and N2-fixation.
The type II clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9... more The type II clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 system (CRISPR/Cas9) has been successfully applied to edit target genes in multiple plant species. However, it remains unknown whether this system can be used for genome editing in grape. In this study, we described genome editing and targeted gene mutation in 'Chardonnay' suspension cells and plants via the CRISPR/Cas9 system. Two single guide RNAs (sgRNAs) were designed to target distinct sites of the L-idonate dehydrogenase gene (IdnDH). CEL I endonuclease assay and sequencing results revealed the expected indel mutations at the target site, and a mutation frequency of 100% was observed in the transgenic cell mass (CM) as well as corresponding regenerated plants with expression of sgRNA1/Cas9. The majority of the detected mutations in transgenic CM were 1-bp insertions, followed by 1-to 3-nucleotide deletions. Off-target activities were also evaluated by sequencing the potential off-target sites, and no obvious off-target events were detected. Our results demonstrated that the CRISPR/Cas9 system is an efficient and specific tool for precise genome editing in grape. Targeted genome editing (TGE) using site-specific nucleases (SSNs) promises to be critical to basic and applied biology research. These powerful SSN tools, comprising zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regulatory interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system (CRISPR/Cas9), introduce targeted DNA double-strand breaks (DSBs) and subsequently trigger DNA repair pathways involving either non-homologous end-joining (NHEJ) or homologous recombination (HR) 1. Both ZFNs and TALENs, which consist of customizable ZF/TALE DNA-binding domains (DBDs) with FokI cleavage domains, have been proven successful in targeted genome modification 2-4. However, disadvantages such as the time required for designing the constructs make these two methods difficult and expensive to use 5,6. Recently, the RNA-guided CRISPR/Cas9 system has been widely used in TGE. There are three types of CRISPR/Cas9 systems (I, II and III), and the type II system with a single Cas9 protein has emerged as a simple but highly efficient tool for TGE 7,8. The Cas9 nuclease is guided by a duplex formed by CRISPR RNA (crRNA) and trans-activating crRNA (tracrRNA) which cleaves the complementary sequence of the crRNA accompanied by an NGG protospacer adjacent motif (PAM) 9,10. The PAM is indispensable for target recognition as it helps the crRNA-tracrRNA-Cas9 complex combine with the target sequence 11,12. In an engineered CRISPR/Cas9 system, the crRNA-tracrRNA duplex has been fused into an artificial single guide RNA (sgRNA) containing a 20-nucleotide (nt) sequence that determines the DNA target site 7,10,13. To date, the CRISPR/Cas9 system has been adopted for TGE successfully in many organisms, including mammalian cells 10,13 , yeast 14 , zebrafish embryos 15 , mice 16 , and numerous herbaceous plants such as Arabidopsis 17-19 , tobacco 19,20 , rice 17,21,22 , wheat 23 , maize 6 , sorghum 23 , soybean 24 , and tomato 25,26. This genome modification is heritable, and the sequence changes in the first generation of stable herbaceous plant transformants persist into the next generation 27,28. In addition, the transient expression of Cas9 and sgRNA in rice and wheat protoplasts also successfully directs genome modification 29. Nevertheless, the CRISPR/Cas9 system has rarely been reported to effectively work in perennial plants except for poplar and citrus 30,31 .
HAL (Le Centre pour la Communication Scientifique Directe), Sep 1, 2017
International audienceThe phenolic composition of aqueous extract from dried leaves of Lippia mul... more International audienceThe phenolic composition of aqueous extract from dried leaves of Lippia multiflora Moldenke was analyzed by liquid chromatography- mass spectrometry (LC-MS) before inverse solid phase fractionation. The crude extract and the different fractions (from FL1 to FL5) obtained after fractionation were then tested in vitro for their effect on two fungi responsible of peanut foliar diseases, Phaeoisariopsispersonata and Pucciniaarachidis. The chemical analysis of the aqueous L. multiflora crude extract indicated the presence of seven phenolic compounds (nuomiosideA, isonuomiside A, samioside, verbascoside, isoverbascoside, alyssonoside and leucoseptoside A) and one monoterpene (geniposide). The antifungal activity, estimated by the efficient rate of the fungal appressorium formation, varied from 33.33% to 58.33% and 5.56% to 38.89% for P. personataand P. arachidis spores, respectively. By spraying the different fractions on artificially contaminated leaves, the best antifungal activity was noticed using FL3 and FL4 fractions, the only one in which the presence of samioside was described. The results of this study suggest that the protecting effect of Lippiaextracts against peanut pathogens may be related to the presence of four phenylethanoid glucosides: verbascoside, nuomoside A, leucoseptoside A and samiosid
The coffee research community has maintained a long ongoing debate regarding the implications of ... more The coffee research community has maintained a long ongoing debate regarding the implications of shade trees in coffee production. Historically, there has been contrasting results and opinions on this matter, thus recommendations for the use of shade (namely in coffee agroforestry systems) are often deemed controversial, particularly due to potential yield declines and farmers’ income. This study is one of the first demonstrating how severalCoffea arabicacultivars respond differently to shade with respect to yield. By standardising more than 200 coffee yield data from various in-field trials, we assembled the so-called “Ristretto” data pool, a one of a kind, open-source dataset, consolidating decades of coffee yield data under shaded systems. With this standardised dataset, our meta-analysis demonstrated significant genotypic heterogeneity in response to shade, showing neutral, inverted U-shaped and decreasing trends between yield and shade cover amongst 18 different cultivars. Thes...
27th Biennial ASIC Conference, Portland, 16-20 September 2018. Book of abstracts 2019, 2019
Nowadays coffee somatic embryogenesis (SE) can be considered as a model for woody perennial crops... more Nowadays coffee somatic embryogenesis (SE) can be considered as a model for woody perennial crops as its industrial application already allowed the dissemination of 50 millions of elite plants in the two cultivated species. The process works with high biological efficiency is observed at all developmental stages and somaclonal variation is mastered. Current research beneficiates from this regeneration model as well as from the progress of coffee genomics and biotechnologies, focuses on two distinct objectives. The recent advances of this research and their respective outputs are reviewed and discussed in this presentation. The first objective is to develop basic research based on-omics methodologies to decipher the fondamental mechanisms associated to cell reprogramming by focusing on two examples: i) Taking advantage of optimized SE protocols, we will unravel totipotency mechanisms and molecular events involved in the key developmental switches occurring during cell dedifferentiation/redifferentiation. A multi approach characterization through cell imaging, massive transcriptomic, epigenetic and metabolomic analyzes is applied at all the key developmental stages from the leaf explant to torpedo-shaped embryos (7 well characterized developmental stages). Big data integration and a system biology approach will provide a thorough knowledge of the expression of totipotency. ii) Coffee embryos acquire the capacity to photosynthetize very early in their developmental process (at the cotyledonary stage). Understanding the events leading to the acquisition of photo-autotrophy is also being studied by ecophysiological and molecular approaches applied to torpedo and cotyledonary-shaped embryo cultures under contrasted light, C02 and sugar conditions. Otherwise, the second objective is to provide - through technological approaches - powerful tools to accelerate the optimization of coffee breeding: i) The high-throughput molecular screening method has been recently developed by Nestle that allows to miniaturize the SE process and opens the way to study the biological effect of new active molecules on particular developmental switches' efficiency. It will also allow the development of miniaturized EMS (Ethyl Methyl Sulphate) mutant banks by simplifying their setting up and further management. ii) The genome editing of coffee genome by the Crispr/Cas9 technology recently described by using embryogenic tissues transformation gives us the possibility to rapidly and precisely manipulate plant genomes to introduce a trait of agronomic interest
Arabica coffee is a main economic crop throughout Central and South American highlands, where mil... more Arabica coffee is a main economic crop throughout Central and South American highlands, where millions of people get primary outcome. Last coffee leaf rust (CLR) epidemic event in 2011, which impacted 53% of the coffee region areas, provoking losses up to USD 500 million, remembered the high vulnerability of the coffee sector to the fungus Hemileia vastatrix, causal agent of this disease and considered as the main restrictive illness for all coffee regions around the world. The main problem remains that the current commercial varieties reputed as "resistant", become sensitive to the CLR. During the last twenty years, coffee geneticist have created several intra-specific hybrids between commercial varieties and wild coffee accessions. Field observations confirmed that coffee hybrids are more productive and less impacted by the CLR even in regions where resistant materials become susceptible. Such field observations are in agreement with the general idea that hybrid plants p...
L'acacia au Sénégal << arbre miracle), du Sénégal, sera considéré comme faisant partie des Acacia... more L'acacia au Sénégal << arbre miracle), du Sénégal, sera considéré comme faisant partie des Acacia et sera indifféremment appelé Faidherbia albida ou Acacia albida dans l'ouvrage. Les communications sont rassemblées selon les thématiques de recherche. Chaque thème regroupe un article de synthèse des travaux dans le domaine abordé ainsi que la présentation des travaux les plus récents. La première partie fait l'état des connaissances en écologie et écophysiologie, en relation avec la contrainte hydrique, pour les espèces socio-économiquement les plus importantes dans les régions sahéliennes, et plus particulièrement A. tortilis, F: albida et A. senegal. La deuxième partie présente les différentes politiques de valorisation agroforestières des acacias réalisées au Sénégal et au Burkina Faso. La troisième partie rassemble les données existantes sur la contribution des acacias dans le cycle de l'azote, l'exposé de synthèse faisant une présentation plus générale des derniers acquis sur I'absorption du nitrate par les racines. La quatrième partie présente les expérimentations réalisées en culture in vitro. La cinquième partie est consacrée à la diversité génétique des acacias et la sixième partie regroupe les connaissances acquises sur les organismes associés aux acacias et leurs interrelations : bactéries symbiotiques fixatrices d'azote, nématodes et champignons symbiotiques. Nous espérons que cet ouvrage, pluridisciplinaire, apportera au lecteur, familier ou non de l'Acacia et des zones arides, des connaissances nouvelles sur cet arbre, même si tous les domaines ne sont pas abordés. Nous tenons à remercier les auteurs ainsi que le comité de lecture pour leur participation enthousiaste à la réalisation de cet ouvrage.
Meloidogyne paranaensis is a root-knot nematode (RKN) affecting coffee production in Latin Americ... more Meloidogyne paranaensis is a root-knot nematode (RKN) affecting coffee production in Latin America. Simultaneous histological and histochemical studies were carried out on Coffea arabica cv Caturra (susceptible), a wild Ethiopian accession of Coffea arabica (resistant ) and a rootstock Coffea canephora cv Nemaya (resistant) after inoculation with this RKN in order to characterize compounds accumulating after infection in resistant cultivars. No hypersensitive-like reaction was induced neither in C. arabica, nor in C. canephora resistant genotypes. Instead, these two resistant coffee genotypes develop the same original resistance mechanisms against M. paranaensis i.e. flavonoids accumulation into giant cells of the feeding sites induced by the RKN. Chlorogenic acids accumulating around infestation sites could act as flavonoid precursors. (Resume d'auteur)
Chemical analysis of aqueous extract of Ziziphus mucronata Willd. was determined by liquid chroma... more Chemical analysis of aqueous extract of Ziziphus mucronata Willd. was determined by liquid chromatography-mass spectrometry (LC-MS) analysis. Among the 11 compounds found, catechin, rutin (quercetin 3-O-rutinoside), delphinidin-3-glucoside, isoquercetin (hyperoside) and quercitrin (quercetine3,7-O-L-dirhanmopyranoside) were identified as the major phenolics components in this aqueous plant extract. To elute the target compounds, the fractionation of crude extract was carried out on solid phase extraction (SPE) columns. The different fractions (from FZ1 to FZ5) obtained after fractionation were evaluated in vitro against economically important foliar fungal pathogens of peanut, including Cercospora arachidicola, Phaeoisariopsis personata and Puccinia arachidis. The treatments with Z. mucronata fractions were compared with negative control (water) and standard solutions of cathechin and rutin (1 mg/mL). All the fractions recorded an inhibitory effect, firstly on conidial germination and germ tube elongation, secondly on disease evolution on peanut leaves previously inoculated by fungi; the level of efficiency of inhibition varied from 40.55 (FZ1 against C. arachidicola) to 57.14% (FZ2 and FZ3 against P. arachidis). Then, spores of P. arachidis seemed to be more sensitive to the treatment.
Background Somatic embryogenesis (SE) is one of the most promising processes for large-scale diss... more Background Somatic embryogenesis (SE) is one of the most promising processes for large-scale dissemination of elite varieties. However, for many plant species, optimizing SE protocols still relies on a trial and error approach. We report the first global scale transcriptome profiling performed at all developmental stages of SE in coffee to unravel the mechanisms that regulate cell fate and totipotency. Results RNA-seq of 48 samples (12 developmental stages x 4 biological replicates) generated 90 million high quality reads per sample, approximately 74% of which were uniquely mapped to the Arabica genome. First, the statistical analysis of transcript data clearly grouped SE developmental stages into seven important phases (Leaf, Dedifferentiation, Primary callus, Embryogenic callus, Embryogenic cell clusters, Redifferentiation and Embryo) enabling the identification of six key developmental phase switches, which are strategic for the overall biological efficiency of embryo regeneratio...
A field experiment was conducted at Bel Air station, in Dakar using 15N isotope dilution techniqu... more A field experiment was conducted at Bel Air station, in Dakar using 15N isotope dilution technique and the non nodulating soybean (Glycine max) variety m129 as reference plant to estimate nitrogen fixation in common bean (Phaseolus vulgaris). Dry matter production and nitrogen accumulation were increased in plants inoculated with Rhizobium strain ISRA 355 compared to uninoculated plants ( +31 % and +50%, respectively) and in 20 N-fertilized plants compared to non N fertilized plants ( +36% and +39%, respectively). In addition, %Ndfa was increased in common bean inoculated with strain ISRA 355 ( +32% higher than non inoculation) or supplied with 20 kg N/ha (+37% higher than non N fertilization). However, the amount of fixed nitrogen was increased by the interaction inoculation x 20 Nfertilization only ( + 155% over the value averaged across all uninoculated plants). From all treatments, estimates of fixed nitrogen were ranged between 63 to 139 kg N /ha. Beside this estimation, nitrog...
Current Plant Science and Biotechnology in Agriculture, 1998
For its contribution to soil fertility in agroforestery systems, Acacia albida Del. appears as on... more For its contribution to soil fertility in agroforestery systems, Acacia albida Del. appears as one of the most useful N2-fixing Sahelian trees. As it shows a low nitrogen fixing potential (Ndoye et al., 1995) and a great capacity to accumulate soil NO3 in its roots (unpublished), in vitro techniques were developed on young inoculated seedlings to evaluate the effect of external NO3 on nodulation and N2-fixation.
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