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NaCl Effects on In Vitro Germination and Growth of Some Senegalese Cowpea (Vigna unguiculata (L.) Walp.) Cultivars  [PDF]
Mahamadou Thiam,Antony Champion,Diaga Diouf,Mame Ourèye SY
ISRN Biotechnology , 2013, DOI: 10.5402/2013/382417
Abstract: Cowpea (Vigna unguiculata (L.) Walp.) is one of the most important grain legumes in sub-Saharian regions. It contributes to man food security by providing a protein-rich diet. However, its production is limited by abiotic stresses such as salinity. This study aims to evaluate the salt tolerance of 15 cowpea cultivars, at germination stage. The seed germination process consisted of sowing them in agarified water (8?g·L?1) supplemented with 6 different concentrations of NaCl (0, 10, 50, 100, 150, and 200?mM). Results highlighted that high salt concentrations drastically reduced germination and significantly delayed the process for all varieties. A cowpea varietal effect towards the salt tolerance was noticed. Genotypes Diongoma, 58-78, and 58-191 were more salt-tolerant cultivars while Mougne and Yacine were more salt-sensitive ones as confirmed in the three groups of the dendrogram. NaCl effects on the early vegetative growth of seedlings were assessed with a tolerant (58-191) and a susceptible (Yacine) cultivar. Morphological (length and dry biomass) and physiological (chlorophyll and proline contents) parameter measurements revealed a negative effect of high (NaCl). However, 58-191 was much more salt tolerant, and the chlorophyll and proline contents were higher than those of Yacine genotype at increasing salt concentrations. 1. Introduction Cowpea (Vigna unguiculata, (L.) Walp.) is a tropical herbaceous leguminous plant belonging to the Fabaceae family. This species is one of the most important grain legume crops in the Sub-saharian regions of Africa because several parts such as dry or fresh seeds (23–32% of protein and 64% of carbohydrate contains), the immature pods, and the leaves are used for human consumption. In addition, dry seeds, pods, and the hay are used for animal feeding during the dry season [1]. For this purpose, cowpea is a valuable source of income for farmers and grain traders in many African countries [2–4]. In Senegal, the economic importance of cowpea is increasing [5] as it is one of the essential crops for rural population diet [6]. Its cultivation is often associated with cereals such as millet, sorghum, and maize [7] due to its ability to establish a nitrogen-fixing symbiosis with Bradyrhizobium and/or mycorrhiza leading to soil fertility improvement [8]. The total cultivated area worldwide is estimated around 9.8 million?ha, with a total production of 3.9 million tons in 2004 [9]. Senegal is a major producer of cowpea in West Africa with an estimated area of 130,730?ha and an average production of 37,648 tons [10]. Salinity
Efecto del estrés por NaCl sobre la anatomía radical y foliar en dos genotipos de Frijol (Vigna unguiculata (L.) Walp.)
Garzón,Paola; García,Marina;
Bioagro , 2011,
Abstract: the effect of nacl stress on leaf and root anatomy in two cowpea genotypes with differences in sensibility to that salt was studied in order to know the probable existence of histological adaptations associated to that differential behavior. seeds of the genotypes ?i-484? (moderate sensibility to salinity) and ?i-490? (sensible to salinity) were sown on inert substrate and six days after sown they were subject to salinization with nacl (100 mm). fourteen days after sown, samples of the root and the primary leaves were taken and fixed in faa until their processing. salt stress induced succulence in the rizodermis and cortex parenchyma of the root, in higher degree in ?i-484?. salinity also produced a reduction in the stele diameter of both genotypes, because of the decrease in number and diameter of the xylem vessels. in the primary leaves of stressed plants, were observed more glandular trichomes, less compact mesophyll and invaginations in the palisade parenchyma cells. in ?i-490? the thickness of the leaf, and that of the adaxial epidermis of palisade and spongy parenchyma, were significantly reduced. these results suggest that the anatomical mechanisms of adaptation to nacl stress in vigna unguiculata are related to the capacity to develop root succulence and the maintenance of foliar tissue integrity.
Effectiveness and efficiency of chemical mutagens in cowpea (Vigna unguiculata (L.) Walp)
D Dhanavel, P Pavadai, L Mullainathan, D Mohana, G Raju, M Girija, C Thilagavathi
African Journal of Biotechnology , 2008,
Abstract: A study was undertaken in a cowpea (Vigna unguiculata (L.) Walp.) variety CO 6 to assess the efficiency and effectiveness of chemical mutagens; ethyl methane sulphonate (EMS), diethyl sulphate (DES) and sodium azide (SA). EMS treatments were found highly effective than the other chemicals. Mutagenic effectiveness and efficiency decreased with increase in all mutagenic treatments.
Plants regeneration from African cowpea variety (Vigna unguiculata L. Walp.)
MS Diallo, A Ndiaye, M Sagna, YK Gassama-Dia
African Journal of Biotechnology , 2008,
Abstract: Vigna unguiculata (L.) Walp. plant was efficiently regenerated from cotyledonary node explants. The shoots multiplication rate was influenced by the presence or the absence of cotyledons. Explants with two entire cotyledons from 5-6-d-old seedling produced the greater number of shoots (8.30) after two weeks on B5 medium supplemented with 1 mg.l-1 BAP. Shoots elongation is optimal on media supplemented with kinetin. Rooting is improved after an induction phase on half strength MS, producing 95.83% of rooted plants. No confined atmosphere surrounding plantlets is essential for survival during acclimatization. The regenerated plants flowered and produced pods and viable seeds.
Floral Biology and Pollination Ecology of Cowpea (Vigna Unguiculata L. Walp)  [cached]
Ige, O. E.,Olotuah, O.F,Akerele, V.
Modern Applied Science , 2011, DOI: 10.5539/mas.v5n4p74
Abstract: Studies on the floral biology and pollination ecology of three varieties of cowpea (Vigna unguiculata L. Walp) were carried out. The varieties studied were Var. Oloyin, Var. Sokoto, and Var. Drum. Cowpea is a self pollinated crop which is encouraged by the arrangements of the floral parts. However, Insects visiting cowpea flowers have been implicated in the movement of pollen from one cowpea plant to another. Flower opening of cowpea begins between 6:00am and 6:30am and closes between 11:30am and 12:00pm. Pollen analysis showed similarities in the pollen morphology of the cowpea varieties. Moreover Var. Drum produced the highest number of pollen grains per flower in terms of pollen productivity.
Targeted mutagenesis in Vigna unguiculata (L.) Walp. and Cucumeropsis mannii (NAUD) in Nigeria
GC Obute, BC Ndukwu, OF Chukwu
African Journal of Biotechnology , 2007,
Abstract: The mutagenic effects of 0.2% aqueous solution of colchicine on gross and micromophological features of seedlings of Vigna unguiculata (L) Walp. and Cucumeropsis mannii (Naud.) were investigated. Terminal buds of two-week old seedlings were assaulted with 0.2% colchicine by the cotton plug and micro syringe methods and performances were monitored until maturity. Colchicine-treated V. unguicu-lata seedlings were observed to grow slower, had malformed leaves, flowered late and produced less number of seeds per pod than the control. Mean values of features like stomatal indices on both the abaxial and adaxial surfaces, terminal leaflet dimensions and trichome distribution between the treated and control were found to be significantly different. In contrast, treated seedlings of C. mannii flowered and fruited earlier than the case of control material. However, growth was also slowed down by the treatment while features like stomatal indices and trichome distribution were not significantly different. The results here have shown that apart from doubling of chromosomes, colchicine can also be used to induce other mutagenic changes which may be of agronomic utility.
Response of Cowpea (Vigna unguiculata L. Walp.) to Water Stress and Phosphorus Fertilization
V.G. Uarrota
Journal of Agronomy , 2010,
Abstract: This study was conducted in the experimental college of agriculture and forestry, in Maputo-Mozambique, in order to evaluate the response of cowpea (Vigna unguiculata L. Walp.) to irrigation and phosphorus and test the hypothesis that high levels of phosphorus improves the tolerance of plants to water stress. We used a variety IT 18 of cowpea, short cycle and ended. The experiment was subdivided into building plots complete block design with five repetitions, the irrigation factor was fixed at the main plot with two levels (with irrigation and without irrigation) and phosphorus factor in sub-plots with 3 levels (0, 20 and 40 kg ha-1 of phosphorus). The fertilization strongly influenced the yield and the number of pods per plant in both irrigation conditions. The effect of fertilizing phosphorus was higher under irrigation. The interaction was significant only for grain yield and number of pods, which means that the effect of phosphorus in these two variables has not been the same for the two levels of irrigation, high levels of phosphate fertilizer (P2O5) have improved the tolerance of cowpea when not irrigated.
Physiological and biochemical responses of cowpea (Vigna unguiculata (L.) Walp) to ozone
Chanin Umponstira,Warin Pimpa,Suckaluck Nanegrungsun
Songklanakarin Journal of Science and Technology , 2006,
Abstract: The aim of this research was to investigate physiological and biochemical responses of cowpea (Vigna unguiculata (L.) Walp) to ozone. There were two main factors of the experiment; level of ozone concentration at 40 and 70 ppb and plant ages at 7 and 21 days. Plants were grown in fumigation chambers in which inlet air was filtered by a charcoal filter. Additional ozone was given 8 hours/day for 7 days in ozone fumigating chambers. The ozone concentration in the control chambers was less than 10 ppb. The results showed the biomass of ozone-fumigated plants was significantly lower and leaf injury of ozone fumigated plants was significantly greater compared to the control group. The major visible-injury symptom appeared as chlorosis on the upper surface of the leaves. Antioxidant levels in the charcoal filtered (CF) plants and ozoned plants had significant differences because of their detoxification role in removing ozone and its derivatives. The ozone treatment of 7-day-old plants showed superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) levels significantly higher than in 21-day-old plants and total ascorbate concentrations significantly lower than 21-day-old plants. These results showed that different ozone concentrations exhibit different effects on antioxidant production. Analysis of antioxidants daily for 7 days found that antioxidant levels rapidly changed. Notably, SOD and total ascorbate could be selected as indicators for ozone-effect monitoring in plants. This indicates that cowpea is sensitive to ozone and may be usable as an ozone bioindicator. In conclusion, plant age, ozone concentration and the duration to exposure to ozone were the main physiological or biochemical responses of cowpea. An efficient defense system was generated from a combination of antioxidants.
Symbiotic functioning and bradyrhizobial biodiversity of cowpea (Vigna unguiculata L. Walp.) in Africa
Flora Pule-Meulenberg, Alphonsus K Belane, Tatiana Krasova-Wade, Felix D Dakora
BMC Microbiology , 2010, DOI: 10.1186/1471-2180-10-89
Abstract: Field measurements of N2 fixation revealed significant differences in plant growth, δ15N values, %Ndfa and amounts of N-fixed between and among the 9 cowpea genotypes in Ghana and South Africa. Following DNA analysis of 270 nodules from the 9 genotypes, 18 strain IGS types were found. Relating nodule function to the 18 IGS types revealed significant differences in IGS type N2-fixing efficiencies. Sequencing the 16S - 23S rDNA gene also revealed 4 clusters, with cluster 2 forming a distinct group that may be a new Bradyrhizobium species. Taken together, our data indicated greater biodiversity of cowpea bradyrhizobia in South Africa relative to Botswana and Ghana.We have shown that cowpea is strongly dependant on N2 fixation for its N nutrition in both South Africa and Ghana. Strain IGS type symbiotic efficiency was assessed for the first time in this study, and a positive correlation was discernible where there was sole nodule occupancy. The differences in IGS type diversity and symbiotic efficiency probably accounts for the genotype × environment interaction that makes it difficult to select superior genotypes for use across Africa. The root-nodule bacteria nodulating cowpea in this study all belonged to the genus Bradyrhizobium. Some strains from Southern Africa were phylogenetically very distinct, suggesting a new Bradyrhizobium species.Cowpea (Vigna unguiculata L. Walp.) is a major food crop in Africa, where its leaves, green pods and grain are eaten as a dietary source of protein. The cowpea grain contains about 23% protein and 57% carbohydrate, while the leaves contain between 27 - 34% protein [1]. The leaves and grain are also supplied as high protein feed and fodder to livestock. Cowpea is the most commonly grown food legume by traditional farmers in Sub-Saharan Africa, possibly because of its relatively wide adaptation to drought and low-nutrient environments. Cowpea freely forms root nodules with some members of the Rhizobiaceae such as Rhizobium and Bradyr
Improved Agrobacterium Mediated Transformation in Cowpea Vigna unguiculata L. Walp.  [PDF]
S. Raveendar,S. Ignacimuthu
Asian Journal of Plant Sciences , 2010,
Abstract: Agrobacterium tumefaciens strain LBA4404 carrying binary vector pCAMBIA1305.1, with a hygromycin phosphotransferase gene (hpt) and a β-glucuronidase (GUS) gene interrupted with an intron, was used for transformation of Vigna unguiculata cotyledonary node explants. High concentration of acetosyringone (200 μM) in the Agrobacterium culture and co-cultivation medium with 1 g L-1 L-cysteine, 250 mg L-1 Na-thiosulphate and 150 mg L-1 dithiothretiol (DTT) proved to be indispensable for successful transformation. Three days old cotyledonary nodes were used for transformation studies. Binary vector pCAMBIA 1305.1 proved to be very efficient for transformation. Stable transformation with 1.61% efficiency was achieved using optimized conditions. Transformed green shoots were rooted on medium containing hygromycin. Transformed shoots tested positive for hpt gene by polymerase chain reaction. GUS activity was detected in cotyledonary nodes and leaves of the putative transformants. Southern analysis of putative transformants showed the integration of hpt into the plant genome.
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