Influence of Growth Regulators on Callogenesis and Somatic Embryo Development in Date Palm (Phoenix dactylifera L.) Sahelian Cultivars

This study provides a physiological analysis of somatic embryogenesis in four elite cultivars of date palms: Ahmar, Amsekhsi, Tijib, and Amaside, from the initial callogenesis to establishment and proliferation of embryogenic suspension cultures. Somatic embryos development and in vitro plants rooting were also studied. For each step, auxins and cytokinins concentrations were optimised. The primary callogenesis from leaf explants of seedlings appeared highly dependent on genotype. Ahmar (80%) and Amsekhsi (76%) appeared highly callogenic, whereas Tijib (10%) and Amaside (2%) produced low amounts of calluses. 2,4-Dichlorophenoxyacetic acid appeared favorable to the induction of primary callogenesis and its effect was enhanced by the addition of benzyl adenine or adenine sulfate. Secondary friable calli obtained from chopped granular calli were used to initiate embryogenic cell suspensions in media supplied with 2,4-dichlorophenoxyacetic acid. Suspension cultures showed a growth rate of fourfold after four subcultures in presence of 2,4-dichlorophenoxyacetic acid 2 mg/L. Our results showed that a seven-day transitory treatment with benzyl adenine 0,5 mg/L was necessary to optimize embryos development. Naphthalene acetic acid induced the development of primary orthogravitropic roots during embryos germination. The comparison with cytofluorometry of nuclear DNA amounts showed no significant difference in ploidy level between regenerated plants and seedlings

Biodiversity field trials to inform reforestation and natural resource management strategies along the African Great Green Wall in Senegal

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Isolation, characterization and cross-species amplification of polymorphic microsatellite markers for Oxytenanthera abyssinica (A. Rich.) Munro (Poaceae)

We developed microsatellite to investigate genetic diversity of Oxytenanthera abyssinica (Bindura bamboo) a bamboo species endemic to Senegal. Using the microsatellite-enriched library method, we identified 14 primer pairs. The primers amplified 10 di-nucleotide repeats and 4 composite motifs, the number of alleles ranged from 5 to 28 with an average of 11.9. The results indicate that these primer pairs offer an appropriate amount of variation to address issues of germplasm characterization, patterns of gene flow and conservation studies. Cross amplification has been tested in other bamboo species

Use of Anopheles salivary biomarker to assess seasonal variation of human exposure to Anopheles bites in children living near rubber and oil palm cultivations in Côte d'Ivoire

International audienceEnvironmental changes related to agricultural practices and activities can impact malaria transmission. In the objective to evaluate this impact on the human-vector contact, the level of human exposure to Anopheles vector bites was assess by an immuno-epidemiological indicator based on the assessment of the human IgG antibody response to the Anopheles gambiae gSG6-P1 salivary peptide, previously validated as a pertinent biomarker. Two cross-sectional surveys were carried out in the dry and rainy season in three villages with intensive agricultural plantations (N'Zikro with rubber cultivation, Ehania-V5 and Ehania-V1 with palm oil exploitation) and in a control village without plantations (Ayébo). Overall, 775 blood samples were collected in filter papers from children aged 1 to 14 years-old for immu-nological analysis by ELISA. The IgG levels to the gSG6-P1 salivary peptide significantly differed between studied villages both in the dry and the rainy seasons (P b 0.0001) and were higher in agricultural villages compared to the control area. In particular, the level of specific IgG in Ehania-V5, located in the heart of palm oil plantations, was higher compared to other agricultural villages. Interestingly, the level of specific IgG levels classically increased between the dry and the rainy season in the control village (P b 0.0001) whereas it remained high in the dry season as observed in the rainy season in agricultural villages. The present study indicated that rubber and oil palm plantations could maintain a high level of human exposure to Anopheles bites during both the dry and rainy seasons. These agricultural activities could therefore represent a permanent factor of malaria transmission risk

Use of Anopheles salivary biomarker to assess seasonal variation of human exposure to Anopheles bites in children living near rubber and oil palm cultivations in Côte d'Ivoire

Environmental changes related to agricultural practices and activities can impact malaria transmission. In the objective to evaluate this impact on the human-vector contact, the level of human exposure to Anopheles vector bites was assess by an immuno-epidemiological indicator based on the assessment of the human IgG antibody response to the Anopheles gambiae gSG6-P1 salivary peptide, previously validated as a pertinent biomarker. Two cross-sectional surveys were carried out in the dry and rainy season in three villages with intensive agricultural plantations (N'Zikro with rubber cultivation, Ehania-V5 and Ehania-V1 with palm oil exploitation) and in a control village without plantations (Ayébo). Overall, 775 blood samples were collected in filter papers from children aged 1 to 14 years-old for immunological analysis by ELISA. The IgG levels to the gSG6-P1 salivary peptide significantly differed between studied villages both in the dry and the rainy seasons (P < 0.0001) and were higher in agricultural villages compared to the control area. In particular, the level of specific IgG in Ehania-V5, located in the heart of palm oil plantations, was higher compared to other agricultural villages. Interestingly, the level of specific IgG levels classically increased between the dry and the rainy season in the control village (P < 0.0001) whereas it remained high in the dry season as observed in the rainy season in agricultural villages. The present study indicated that rubber and oil palm plantations could maintain a high level of human exposure to Anopheles bites during both the dry and rainy seasons. These agricultural activities could therefore represent a permanent factor of malaria transmission risk

Chloroplast DNA phylogeography suggests a West African centre of origin for the baobab, Adansonia digitata L. (Bombacoideae, Malvaceae)

International audienceThe African baobab (Adansonia digitata L.) is an emblematic, culturally important, and physically huge tropical tree species whose natural geographical distribution comprises most of tropical Africa, but also small patches of southern Arabia, and several Atlantic and Indian Ocean islands surrounding the African continent, notably including Madagascar. We analysed the polymerase chain reaction-restriction fragment length polymorphism of five chloroplast DNA fragments obtained from 344 individuals of A. digitata collected from 74 populations covering the entire extant distribution range of the species. Our goal was to reconstruct the phylogeographical history of the species and, if possible, to identify its centre of origin, which has been a subject of controversy for many decades. We identified five haplotypes whose distribution is clearly geographically structured. Using several species of Adansonia and of closely related genera as outgroups, the haplotypes showed a clear phylogeographical pattern of three groups. Two are phylogenetically related to the outgroup taxa, and are distributed in West Africa. The third group is substantially more differentiated genetically from outgroup species, and it corresponds to southern and eastern Africa, Arabia and the Indian Ocean islands, including Madagascar. According to our results, the tetraploid A. digitata, or its diploid progenitor, probably originated in West Africa and migrated subsequently throughout the tropical parts of that continent, and beyond, by natural and human-mediated terrestrial and overseas dispersal

Evaluation of Human Exposure to Aedes Bites in Rubber and Palm Cultivations Using an Immunoepidemiological Biomarker

International audienceArbovirus infections, mainly transmitted by Aedes mosquito, are emerging in Africa. Efficient vector control requires an understanding of ecological factors which could impact on the risk of transmission, such as environmental changes linked to agricultural practices. The present study aims to assess the level of human exposure to Aedes mosquito bites in different agroecosystem area, using an immunological tool which quantifies human IgG antibody response to one Ae. aegypti salivary peptide. Specific IgG responses were assessed during dry and rainy seasons, in children living in different villages in Côte d'Ivoire: N'Zikro (rubber and oil palm exploitations), Ehania-V5 (oil palm), and Ayébo (without intensive agricultural activities). In the dry season, specific IgG levels were significantly lower in Ayébo compared to Ehania-V5 and N'Zikro and, interestingly, were similarly high in both villages with cultivations. In the rainy season, no difference of specific IgG was observed between villages. Specific IgG responses remained therefore high during both seasons in villages associated with intensive agricultural. The rubber and oil palm cultivations could maintain a high level of human exposure to Aedes mosquito bites during both dry and rainy seasons. These agricultural activities could represent a permanent risk factor of the transmission of arboviruses