Genetic diversity and gene flow revealed by microsatellite DNA markers in some accessions of African Plum (Dacryodes edulis) in Cameroon

Dacryodes edulis is a multipurpose tree integrated in the cropping system of Central African region still dominated by subsistence agriculture. Some populations grown are wild which can provide information on the domestication process, and could also represent a potential source of gene flow. Leaves samples for DNA extraction were collected from wild forms in Mbakwa supe region and from cultivated forms in Yaounde and Santchou region. Six microsatellites DNA markers were employed in genotyping to analyze population structure and gene flow. Amplification rate was high and genotyping revealed high level of genetic variation. The overall polymorphic level at the six loci was also high with average expected heterozygosity of 0.53; polymorphism of 0.46; mean allelic diversity of 0.5 and mean allele number of 8.33. There were no clear differences with only 1% variation among the three populations and 6% variation among individuals within populations. In contrast, the rate of heterozygosis was high in all the three populations. Both the number of migrant per generation (Nm=20) and the Wright’s Fstatistics (FST=0.012) suggest that there was substantial gene flow among the populations. These findings indicate that D. edulis possess a great potential of pollen dispersal and dominant crosspollination within populations. Most of the loci with private alleles (45%) were found in wild individuals which could be a source of pollen for crossing their cultivated relatives.Key words: Dacryodes edulis, domestication, genetic diversity and structure

Efecto de fitohormonas exógenas sobre la evolución de ciertos parámetros bioquímicos durante la embriogénesis de células somáticas de

Introduction. Pour introduire Ricinodendron heudelotii (Euphorbiacée) dans les agrosystèmes, des plantules ayant un système racinaire pivotant peuvent être produites par embryogenèse somatique in vitro. Nous avons étudié l’effet de quelques phytohormones exogènes sur certains paramètres biochimiques caractéristiques de l’embryogenèse somatique de l’espèce. Matériel et méthodes. Des cals et des embryons somatiques ont été induits par culture de fragments de feuilles sur un milieu de base enrichi en (1, 2 ou 3) mg 2,4-D·L–1 ou de combinaisons [2,4-D / kinétine] ou [2,4-D / BAP] impliquant différentes concentrations des hormones. Les extractions et analyses des sucres totaux, phénols, protéines totales et activité des peroxydases ont été faites après (30, 50 et 70) j de développement des cals. Résultats. Après 30 j de culture, les meilleurs pourcentages d’explants formant des cals ont varié de 72,1 % à 100 % selon les phyto-hormones utilisées. Après 50 j de culture, ces cals ont formé des amas globulaires de cellules en division (nodules embryonnaires). Après 70 j de culture, 17,4 % des cals ont différencié les embryons somatiques multiformes en présence de 3 mg 2,4-D·L–1; 23,1 %, en présence de [1 mg 2,4-D·L–1 + 1 mg kinétine·L–1] et 27,6 %, [1 mg 2,4-D·L–1 + 2 mg BAP·L–1]. La teneur en sucres a été la plus élevée à 30 j (formation des cals) et 50 j (formation des nodules embryonnaires sur cals), alors que les teneurs en phénols, en protéines et l’activité des peroxydases ont été plus élevées à 70 j (différenciation des embryons somatiques sur cals). Discussion et conclusion. À l’instar de ce qui se passe chez d’autres espèces végétales, chez R. heudelotii, les phytohormones exogènes interviendraient dans le contrôle du métabolisme des paramètres biochimiques impliqués dans la formation des embryons somatiques et de leur développement

Physico-chemical characterisation and classification of fruits of

Introduction. A study of accessions from the major production areas of Dacryodes edulis (Don) Lam. (Burseraceae) in Cameroon was carried out in order to assess the impact of pedoclimatic parameters and genetic factors on the characteristics and the classification of the fruits. The work focused on statistical analysis of fruit morphological and chemical parameters to distinguish accessions. Materials and methods. The fruits were collected from five localities of Cameroon (Obala, Boumyebel, Makenene, Njombe and Kekem). Twenty-six characters, among which were eleven quantitative morphological, nine qualitative morphological and six chemical characters, were the object of a correlation analysis, a principal component analysis and hierarchical classification. Results. Among the twenty-six characters studied, eighteen presented interesting morpho-chemical characters to discriminate the accessions. The fruit quantitative morphological characters were not significantly different, while the qualitative morphological and chemical characters showed significant differences for the localities concerned. A principal component analysis and hierarchical classification distinguished three major groups at a genetic distance of between 5.70 and 6.92: group I consists of accessions from Makenene and Kekem, discriminated by five characters (lipids, protein, grain colour, texture and colour of the mesocarp); group II consists of accessions from Njombe and Obala and was discriminated by six characters (weight of fruits, amino acids, sugars, phenols, epicarp colour and shape of grains); group III consists of the accession from Boumyebel and was discriminated by seven characters (fruit length and diameter; [fruit diameter / fruit length] ratio; weight of fruit, mesocarp and grain; and mesocarp thickness). Discussion and conclusion. Like agro-forestry species such as Ricinodendron heudelotii and Irvingia gabonensis, D. edulis presents intra-specific variations that are related to pedoclimatic conditions and genetic factors

Bactericidal and Bacteriostatic Effects of Four Different Parts of 2 Plants Moringa Extracts against the Bacteria Vibrio cholerae and Salmonella typhi, and some Phytochemical Properties

International audienceBackground and Objectives: Typhoid fever and cholera are two major health challenges in many developing countries. The use of extracts of the plants Moringa for their treatment is often done without perfect knowledge of the antimicrobial properties of each part of plant. This study aims to evaluate the bactericidal and bacteriostatic effects of extracts of M. oleifera and M. stenopetala against the bacteria S. typhi and V. cholerae which cause typhoid fever and cholera respectively. Materials and Methods: Four different parts (leaves, seeds, stem, and roots) of each plant species were dried and then ground. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of the extracts of each part of the plants against the considered bacteria were determined by dilution method. Their phytochemical profiles were determined by chromatographic and mass spectral analyses. Results: It has been noted that MICs and MBCs varied from one part to another of the same Moringa species, and from one bacterium to another for the same extract. With M. oleifera, the lowest MBC (0.078 mg/mL) against S. typhi and V. cholerae came from seeds and roots extracts, respectively. With M. stenopetala, the lowest MBCs against S. typhi (0.156 mg/mL) and V. cholerae (0.312 mg/mL) were from seeds extracts. Extracts of different parts of M. oleifera have bactericidal effects against S. typhi, and bacteriostatic effects against V. cholerae. Extracts from all considered parts of M. stenopetala have bacteriostatic effects against both bacteria. Although some phytochemicals were found in both Moringa, others were specific to one species or to a given part. Conclusion: In case of co-infection by both bacteria, M. oleifera roots extracts could be the most recommended in the treatment because of their lowest MIC and MBC. With M. stenopetala, roots and seeds extracts could be the most recommended because of their relatively lower MIC and MBC, respectively. The next studies will determine for each microorganism, the activity of each identified and purified chemical compound. GRAPHICAL ABSTRAC

Biochemical aspects of single-node cuttings of Ricinodendron heudelotii (Baill.) in relation with rooting

Ricinodendron heudelotii (Njansang) is a valuable multipurpose tree species retained for domestication in Central and Western African regions. To measure the ability of rooting in relation with biochemical changes, basal single-node leafy cuttings were treated with different concentrations of indole-3-butyric acid (IBA), and 1-naphthaleneacetic acid (NAA) and cultured in fine sand media under poly-propagator system. The adventitious rooting was obtained in three distinct stages: Induction (0 to 20 days), initiation (20 to 30 days) and expression (30 to 40 days). Rooting response was higher within nodal cuttings pretreated with IBA than those pretreated with NAA. Polyphenoloxidase activity started to increase both in treated and control cutting during the initiation stage of the experiment and decreased after root emergence only in treated cuttings. Indole-3 acetic acid (IAA)-oxidase activity of auxin treated cuttings decreased as compared to the control. The peroxidase activity in IBA-treated cuttings increased slowly at the initiation stages and lightly at the expression stage. Total phenolic content was higher in IBA-treated cutting particularly at the initiation and expression stages. Phenolics andpolyphenoloxidase might be playing key role for emergence of adventitious rooting and can be used as rooting enhancer in R. heudelotii.Keywords: Auxins, enzyme activity, nodal cutting, Ricinodendron heudelotii, vegetative propagationAfrican Journal of Biotechnology Vol. 12(10), pp. 1049-105

Effects of aqueous and hydro-ethanolic Moringa oleifera Lam leaf extracts on the cultivability of 2 Bacillus strains isolated from rainwater

International audienceIn most developing countries, rainwater is used by many people to meet their water needs. Many Bacillus species known to be harmful to humans have also been identified in rainwater samples. Improving the microbiological quality of the rainwater using modern techniques seems expensivein rural areas for poor people. Extracts from several medicinal plants are often used in rural areas to treat certain bacterial infections. Water and alcohol are often used in traditional therapy to extract the principles of medicinal plants. But little is known about their functional differences orsimilarities. This study aims to assess the effects of aqueous and hydro-ethanolic leaf extracts of Moringa oleifera Lam on the cultivability of Bacillus cereus and Bacillus thuringiensis isolated from rainwater. Leaf extracts of concentrations 2, 1.5, 1 and 0.5 g/L in contact with cells were incubated at 23°C and 37°C for 3 h, 6 h, 9 h and 24 h. The results showed a decrease in cultivable cells abundance. In most cases, cell abundances between the aqueous extract and hydro-ethanolic extract were not significantly different (P>0.05). A significant difference (P<0.05) was noted amongst cell abundances from each incubation period to another. The effectiveness of each extract for cell inhibition was evaluated and then expressed as a decrease percentage in the number of cultivable cells. A decrease in cultivable B. thuringiensis abundance varied from 75.09 to 99.68% in hydro-ethanolic extract and from 70.75 to 97.94% in aqueous extract. That of B. cereus varied from 0 to 98.86% in hydro-ethanolic extract and from 41.09 to 92.20% in the other. This difference could be linked to the differences in the cell species intrinsic properties. It could also be linked to the presence of some compounds identified. Some of these compounds would act as nutrients for cell growth, counterbalancing cell inhibition caused by others that have antimicrobial effects