Utilisation des mutations induites pour l'étude de l'embryogenèse chez le haricot Phaseolus vulgaris L. et deux plantes modèles Arabidopsis thaliana (L.) Heynh. et Zea mays L.

Use of induced mutations in embryogenesis study in bean Phaseolus vulgaris L. and two model plants, Arabidopsis thaliana (L.) Heynh. and Zea mays L.. Breeding of common bean, Phaseolus vulgaris L., through interspecific hybridizations with the species Phaseolus coccineus L. and Phaseolus polyanthus Greenm. as female parents leads to the abortion of immature embryos. Identification of genes required for embryo development could partly explain the abortion of hybrid embryos; induced mutations could thus be an alternative to identify key genes involved in Phaseolus embryogenesis. This paper is a review which shows a few examples of the use of induced mutations in the identification of essential genes for embryogenesis in two model plants, Arabidopsis thaliana (L.) Heyhn. for dicots and Zea mays L. for monocots. In these two species, embryo development mutants have been isolated using insertional mutagenesis and chemical mutagenesis with Ethyl Methane Sulfonate (EMS). Arabidopsis embryo mutants are affected in apical-basal axis polarity, radial pattern and in post-embryonic stages. Some Arabidopsis embryo mutants are defected in auxin signalisation. In maize, defective kernel (dek) mutants are affected in the embryo and the endosperm, while in embryo specific (emb) mutants, only the embryo is affected. In common bean, plants deficient in seed development were isolated using EMS mutagenesis. Embryos inside the seeds fail to growth at different stages of development and show abnormalities mainly in the suspensor and the cotyledons

Effects of the numbers of foliar insecticide applications on the production of the oilseed watermelon citrullus lanatus

Citrullus lanatus is a creeping annual vine species belong to Cucurbitaceae. This plant is cultivated for its oleaginous seeds that are important in the social and cultural life of several peoples in Africa. Thus to improve its production field studies were conducted during two cropping seasons of 2007 to define an economically beneficial foliar insecticide application frequency to manage insect pests on the oleaginous C. lanatus in a woodland savannah zone of Côte d’Ivoire. Zero (control) to four sprays of a foliar carbamate-based insecticide (Cypercal EC 50) were  applied at four plant growth stages (seedling emergence, stem creeping, male flowering, and female flowering) in a completely randomised block design experiment. Four beetles and one ladybird species were identified as the most damaging insect pests on the target crop. Seed yield and most of the yield components analyzed increased with increasing number of sprays, the highest values being obtained with 3-4 sprays, according to the growing season. Between seasons variations were noted for the seed yield and all the yield components, and attributed to the negative influence of low temperature and heavy rainfalls occurring during the second growing season (18 July to 16 December 2007).Keywords. Foliar insecticide, Carbamate, Citrullus lanatus, Cucurbitaceae, Yield, pest insects, beetles, ladybird

Barrières pré-zygotiques chez les hybrides entre formes sauvages du niébé, Vigna unguilata (L.) Walp.

Hybrids pre-zygotic barriers between wild forms of cowpea. The wild forms of cowpea, Vigna unguiculata, constitute an important gene pool insufficiently exploited for the improvement of the cultivated form. In order to promote the use of these wild forms in the genetic improvement programmes, we undertook to understand the various incompatibility reactions which appear in the crosses between wild forms. Efforts were concentrated to understand the incompatibility barriers in the hybridizations between subsp. baoulensis NI 933 and the other wild forms of V. unguiculata. Thanks to the use of the aniline blue fluorescence, we observed a high frequency of pre-zygotic barriers. They appear in three sites, i.e. the higher and lower third of the style, and within the ovary. However, these incompatibility barriers are not absolute. Indeed, in our hybridizations, more than 4% of the ovules were fertilized in the various studied combinations

Analysis of incompatibility barriers during cross-pollinations among Phaseolus L. and other leguminous plants

Plant breeding is intended to seek for ways of realizing a genetic structure adapted to criteria and population needs. In this context, cross-pollinations are for great interest. They offer the means of creating a wide genotypic variability. However, a limited number of species are able to undergo hybridization studies. In Phaseolus L., improvement can be envisioned by either exploiting the primary genetic pool of the species, or the genetic variability of other species. In fact, there are wild or wild-like species more resistant to stresses or diseases than the cultivated ones. The methods of embryo rescues facilitate the interspecific crosses and contribute to exploiting the available genetic diversity within plant germplasm. Difficulties related to obtaining hybrids in grain legumes, and Phaseolus L. in particular, are reported in this research. It is possible to avoid the incompatibility barriers based on their appearance time. When they are pre-zygotic, the use of growth regulators during pollination is recommended. The in vitro explants culture is the most usual method to overcome the post-zygotic barriers. The mechanisms leading to abortion of hybrid embryos, as well as adequate methods to overcome the interspecific incompatibilities should be subjected to further studies.Keywords: Abortion, hybridization, interspecific barriers, Phaseolus L., plant embryos

Amélioration du taux de multiplication in vitro de Jatropha curcas L

Improvement of the Rate of in vitro Multiplication of Jatropha curcas L. In order to improve the in vitro multiplication rate (number of shoots/explant/subculture) of Jatropha curcas L. axillary nodes taken from young plants of two accessions of this species (originating from Cameroon and Senegal) have been cultivated for three weeks on a MS medium supplemented with 8.87 μM BAP, 4.92 μM IBA, and 30 g/l sucrose at pH 5.7 ± 0.1, and solidified with 0.7% agar. The shoots obtained from each original explant were then transferred to proliferation media (PM) consisting of MS medium supplemented with 2.21 to 8.9 μM BA or 2.21 to 8.9 μM kinetin in combination with 2.46 μM IBA. Each combination was completed with 33.12 μM adenine sulfate, 82.92 μM of glutamine and 30 g / L sucrose. The best multiplication rate was obtained for the PM medium containing 6.65 μM BA and 2.46 μM AIB. On this medium 42.72 ± 3.22 and 38.15 ± 4.7 shoots/explant were obtained respectively for the accessions from Cameroon and Senegal after 6 weeks of culture, and the mean multiplication rates were 8.27 ± 1.27 (accession from Cameroon) and 7.89 ± 1.13 (accession from Senegal) shoots per explant during the 7 following subcultures (3 weeks/subculture). This medium was also the one that allowed the best overall growth in shoot height. Leafy shoots obtained have been rooted in a medium containing half of the major mineral components of MS supplemented with 5.7 μM IBA, 1.5% sucrose and solidified with 0.7% agar, then acclimated with a survival rate of 97%. These results allow considering the establishment of industrial units of plantlet multiplication from elite clones of Jatropha curcas

Utilisation de la PCR-RFLP sur de l'ADN chloro-plastique pour l'étude des relations phylogénétiques au sein du genre Phaseolus

Phylogenetic relationships among 74 accessions belonging to six species of Phaseolus are investigated using variation in chloroplast DNA assessed according to a PCR-RFLP protocol. Three fragments of chloroplast DNA are amplified using universal primers, and then digested with 10 restriction enzymes. Thirty-six haplotypes are identified on the basis of the polymorphism in fragment number and size. Three main phylogenetic groups, strongly supported through bootstrap analysis, are identified: (1) accessions from Phaseolus lunatus and Phaseolus xolocotzii; (2) accessions from Phaseolus glabellus; (3) accessions from Phaseolus vulgaris, Phaseolus polyanthus and Phaseolus coccineus. Within the third group, accessions of Phaseolus coccineus are scattered along the phylogenetic tree, which provides some evidence that coccineus accessions are paraphyletic with respect to Phaseolus vulgaris and Phaseolus polyanthus. An analysis of molecular variance applied on four species show that they are significantly differentiated with 79% of molecular variance among species and 21% within species. The results agree with previous investigations on chloroplast DNA variation in the genus Phaseolus, and suggest that PCRRFLP methods, which are technically less labour-intensive than previous methods, are of great value for phylogenetic investigations at the generic level

Effet de la Saison de Culture et de la Densité des Plants sur les Adventices et la Production de la Cucurbite oléagineuse Citrullus lanatus (Thunberg) Matsum. & Nakai (Cucurbitaceae)

Citrullus lanatus a été cultivée sur 2 périodes de l’année (saison 1 : d’Avril à Juillet et saison 2 : de Septembre à Décembre 2006) à la ferme expérimentale de l’Université d’Abobo-Adjamé en Côte d’Ivoire. Ces études visaient à déterminer la densité de la cucurbite qui assure un contrôle biologique des adventices et celle qui permet une meilleure productivité de cette culture mineure. Le dispositif expérimental est un bloc complètement randomisé, subdivisé en parcelles élémentaires de 6 m × 6 m avec trois répétitions par traitement. Sept paramètres agronomiques chez la cucurbite et la densité d’adventices (estimée uniquement au cours de la 1ère saison) ont été analysés dans trois systèmes culturaux. L’analyse a été suivie de tests de comparaisons multiples. Il en ressort que l’augmentation de la densité de la cucurbite réduit le nombre d’adventices. Les résultats montrent également que les composantes de rendement de la cucurbite, excepté le nombre de fruits à l’hectare (NFHa), diminuent avec la densité de semis. Cette diminution est plus prononcée à la deuxième saison. Sur la base des résultats obtenus, il a été suggéré de cultiver C. lanatus, à forte densité pour lutter contre les adventices et à faible densité pour obtenir des effets bénéfiques au niveau de son rendement.Mots-clés : Citrullus lanatus – densité – adventives – rendement

Les hybridations interspecifiques dans le genre Phaseolus : selection des genotypes compatibles et caracterisation des hybrides interspecifiques

La réussite de l’introgression de caractères utiles chez le haricot commun P. vulgaris à partir des deux espèces P. coccineus et P. polyanthus dépend en partie des génotypes utilisés. Ce travail vise à identifier des génotypes de Phaseolus compatibles lors des hybridations interspécifiques et à identifier les hybrides issus des croisements entre P. vulgaris utilisé comme parent mâle et les deux autres espèces utilisées comme parents femelles. Dans les croisements P. coccineus x P. vulgaris, le taux de gousses avortées audelà de 8 JAP est d’environ 12 %. Quatre gousses supposées hybrides ont été obtenues. Pour les hybridations P. polyanthus x P. vulgaris, le taux de gousses avortés au-delà de 8 JAP est d’environ 18 % et une seule gousse supposée hybride a été produite. Les hybrides issus des deux combinaisons interspécifiques ont été mis en évidence au moyen de caractères morphologiques et grâce à un marqueur moléculaire microsatellite. Les génotypes retenus pour leur bonne aptitude à la combinaison, en tenant compte des taux d’avortement au-delà de 8 JAP, sont les suivants : NI637 et G21245 pour P. vulgaris, NI889 et NI16 pour P. coccineus, NI1015 et G35348 pour P. polyanthus. Mots clés : Phaseolus, hybridations interspécifiques, caractères morphologiques, marqueur microsatellite (SSR).INTERSPECIFIC HYBRIDIZATIONSWITHIN THE GENUS PhaseolusSuccessful introgression of useful traits in common bean P. vulgaris from the two species P. coccineus and P. polyanthus depends in part to genotypes used. This work aims to identify genotypes of Phaseolus compatible during interspecific crosses and to identify hybrids from crosses between P. vulgaris used as male parent and the other two species used as female parents. In crosses P. coccineus x P. vulgaris, the rate of pod abortion 8 days after pollination (DAP) is around 12 %. Four putative hybrid pods were obtained. For hybridizations P. polyanthus x P. vulgaris, the rate of pod abortion 8 DAP is around 18 % and one putative hybrid pod was produced. The hybrid nature of one plant from each interspecific combination was confirmed using morphological characters and one microsatellite molecular marker. Genotypes selected for good combining abilities, considering pod abortion rates 8 DAP are NI637 and G21245 for P. vulgaris, NI889 and NI16 for P. coccineus, NI1015 and G35348 for P. polyanthus.Keywords : Phaseolus, interspecific hybridizations, morphological characters, microsatellite marker (SSR)

Optimization of ISSR marker for African edible-seeded Cucurbitaceae species’ genetic diversity analysis

We applied a molecular approach using inter-simple sequence repeat (ISSR) markers on three African edible-seeded cucurbits (Citrullus lanatus L. Matsumura and Nakai, Cucumeropsis mannii L. Naudin and Cucumis melo var. agrestis L. Naudin). To obtain clear and reproducible bands on 1.5% agarose gels, we screened 21 ISSR primers and three parameters (annealing temperature, gel tray, and voltage and running time). The resolution of 11 ISSR markers was performed, with optimal annealing temperature (Ta) varying from 50 to 52°C. The best combination to obtain clear and well-distinguished band patterns was 1.5% agarose gel with a 20-lanes tray (6 mm width) at 80 V for 5 h. Applying the 11 ISSR primers on DNA extracted from an accession of C. lanatus, 66 bands with 4 to 11 bands per primer was observed.Keywords: ISSR, Cucurbits, genetic diversity, molecular markers, optimizatio

Neuronal differentiation of hair-follicle-bulge-derived stem cells co-cultured with mouse cochlear modiolus explants

Stem-cell-based repair of auditory neurons may represent an attractive therapeutic option to restore sensorineural hearing loss. Hair-follicle-bulge-derived stem cells (HFBSCs) are promising candidates for this type of therapy, because they (1) have migratory properties, enabling migration after transplantation, (2) can differentiate into sensory neurons and glial cells, and (3) can easily be harvested in relatively high numbers. However, HFBSCs have never been used for this purpose. We hypothesized that HFBSCs can be used for cell-based repair of the auditory nerve and we have examined their migration and incorporation into cochlear modiolus explants and their subsequent differentiation. Modiolus explants obtained from adult wild-type mice were cultured in the presence of EF1α-copGFP-transduced HFBSCs, constitutively expressing copepod green fluorescent protein (copGFP). Also, modiolus explants without hair cells were co-cultured with DCX-copGFP-transduced HFBSCs, which demonstrate copGFP upon doublecortin expression during neuronal differentiation. Velocity of HFBSC migration towards modiolus explants was calculated, and after two weeks, co-cultures were fixed and processed for immunohistochemical staining. EF1α-copGFP HFBSC migration velocity was fast: 80.5 ± 6.1 μm/h. After arrival in the explant, the cells formed a fascicular pattern and changed their phenotype into an ATOH1-positive neuronal cell type. DCX-copGFP HFBSCs became green-fluorescent after integration into the explants, confirming neuronal differentiation of the cells. These results show that HFBSC-derived neuronal progenitors are migratory and can integrate into cochlear modiolus explants, while adapting their phenotype depending on this micro-environment. Thus, HFBSCs show potential to be employed in cell-based therapies for auditory nerve repair