Effect of water stress induced by polyethylene glycol 6000 on the somatic embryos conversion into whole plantlets in cocoa (Theobroma cacao L.)

Rainfall scarcity due to climate change is a major constraint that limits cocoa productivity in Côte d'Ivoire. This work aims to regenerate cocoa plants tolerant to water stress using in vitro methods. Staminode and petal explants of the genotypes C1, C9, C14, C15, C16, C18 and C20 were used to produce somatic embryos through two methods. Firstly, somatic embryos were induced under stressfull conditions on media containing different concentrations of polyethylene glycol (PEG) 6000 (0; 25; 50; 75; 100 and 125 g/l) and secondly; under non-stressed conditions. Somatic embryos were placed on a conversion medium in the same stress condition. The number of regenerants decreased with the increase in the concentration of PEG with all genotypes. Only genotypes C1 and C15 regenerated plantlets under water stress conditions. The sensitive genotypes C9, C14, C16, C18 and C20 have not developed plantlets on media containing PEG. The plantlets produced under water deficit conditions exhibited a reduction in stem length and leaves number and an increase in length or offset of the high number of roots. The survival rate of regenerants during acclimatization was higher on the sandsubstrate. The selected genotypes could be used in an improvement program of cocoa production.Keywords: Climate change; plant regeneration; genotype; tolerance; drought; in vitr

Influence Du Mode De Culture Du Maïs [Zea Mays (L.) (Poaceae)] Et Du Niébé [Vigna Unguiculata (L.) Walp (Fabaceae)] Sur La Masse Et La Qualité Nutritionnelle Des Graines Des Deux Espèces

Cowpea cultivars C1, C2 and C3 were intercropped with maize in intraline pattern (MND); inter-line pattern (1M1C) and strip-intercropping (2M4C) to determine influence of the cultivation method on the mass of 100 seeds and the nutritional quality of the seeds. Pure maize and cowpea crops were used as control plots. One hundred (100) seeds mass and nutrient content of maize and cowpea seed was determined. The results showed that 100 seeds mass (22,59g in 2015 and 21,03g in 2016) and the highest level of protein (9,87g in 2015 and 11,13g in 2016) maize seeds have been obtained with MC1I. Phosphorus levels were higher with maize seeds from sole maize fertilized MV+P (0,27g in 2015 and 0,25g in 2016). However the 2M4C1 intercropping 2M4C1 (0,24g in 2015 and 0,23 in 2016), 2M4N3 (0,24g in 2015 and 0,25g in 2016) and 1M1C3 (0,24g in 2015 and 0,24g in 2016) may be recommended for their phosphorus content in maize seeds. The 2M4C1 intercropping (12,29g in 2015 et 13,05g in 2016) expressed the highest mass of 100 seeds of cowpea. Intercropping using 2M4C3 can be recommended for improved fat content (1,27g in 2015 and 1,38g in 2016) and phosphorus (200,36g in 2015 and 200,33g in 2016) in cowpea seeds

PROSPECTION, COLLECTE ET CARACTERISATION AGROMORPHOLOGIQUE DES MORPHOTYPES DE VOANDZOU [VIGNA SUBTERRANEA (L.) VERDC. (FABACEAE)] DE LA ZONE SAVANICOLE EN COTE D’IVOIRE

In Africa, Bambara groundnut [Vigna subterranea (L.) Verdc.] is the third most important grain-legume after groundnut (Arachis hypogaea ) and cowpea (Vigna unguiculata). An extended mission of exploration and collection has been achieved in the savannah area of Côte d’Ivoire to acquire knowledge on the plant management by farmers. Agromorphological performances of 15 collected landraces have been evaluated in experimental plots established in Korhogo. Sixty six (66) villages were visited and 156 accessions of Bambara groundnut were collected. The results showed that Bambara groundnut is mainly cultivated by women (90 %). The landraces Ci2, Ci5, Ci6 and Ci1 have been identified as the mostly grown and consumed in savannah area. Chemical products ( cypermetrin and profenofos) and ash were often used for seeds storage. Moreover, Ocimum canum , Hyptis spicigera , Azadirachta indica and Khaya senegalensis are also used in seeds stock. Multifactorial analysis indicated three distinctive groups of landrace: Early maturing landraces with low vegetative development and low seed yield; late maturing landraces with high vegetative development and high seed yield; late maturing landraces with medium vegetative development and high value of seed yield components

Plant regeneration <em>via</em> direct shoot organogenesis from cotyledon explants of Bambara groundnut, <em>Vigna subterranea</em> (L.) Verdc.

International audienceBambara groundnut (Vigna subterranea [L.] Verdc.) is mainly grown for human consumption. However, several factors limit a wider adoption of the crop including the presence of antinutritional factors in the seeds that lower product quality and protein availability but also the plant susceptibility to pests and diseases. Tissue culture techniques are very scanty in Bambara groundnut and should be developed before carrying out genetic transformation for the crop improvement. Therefore, here, an efficient system for in vitro shoot induction from cotyledons derived from mature seeds has been established. Different types and concentrations of plant growth regulators were used to induce buds in embryo-free cotyledon explants. Cotyledons were cut transversally or longitudinally into three segments: proximal, middle and distal part. The influence of explant orientation on the medium, the type of segment and landrace has then been studied. Benzylaminopurine (3 mg.l(-1)) alone or combined with a-naphthaleneacetic acid (0.05 mg.l(-1)) induced multiple shoot formations. The organogenic potential was restricted to the proximal segment of cotyledons. Frequency of bud induction (30%) and average number of buds per explant (12) were higher when the adaxial side of the proximal segment was in contact with the medium. Shoot regeneration from cotyledon explants of ten Bambara landraces revealed that the response is genotype-dependent with varieties Ci6, Ci2, Ci4 and Ci15 exhibiting 20 to 30% shoot regeneration and six to ten buds per explant. Regenerated shoot buds excised from explants were elongated and rooted on MS basal medium devoid of plant growth regulators. All rooted plantlets survived to the transfer on a sand soil mixture, and morphologically normal plants were hardened and transferred to greenhouse for further growth to maturity and seed set

Effect of antioxidants on the callus induction and the development of somatic embryogenesis of cocoa [Theobroma cacao (L.)]

Abstract The browning of plant tissue and organs is a major constraint in tissue culture of cocoa (Theobroma cacao L.). This study aims to evaluate callogenic and embryogenic potentialities of three genotypes cocoa on culture media supplemented with different types and concentrations of antioxidants. Polyvinylpyrrolidone (PVP), ascorbic acid, silver nitrate and cysteine were used as antioxidant agents. The explants staminode and petal were excised from immature buds of the flowers of genotypes cocoa C1, C8 and C14. The results showed that the induction rate of callus derived from the petal and the staminode varied with the genotypes tested. Except 21 mg/l of silver nitrate, the others antioxidants used namely ascorbic acid, PVP and cysteine have enhanced the callus induction of the genotype C8. In comparison with the control, the callus browning of the three genotypes was reduced two to three times when the culture media were supplemented with various concentrations of the silver nitrate. After 72 days of culture, somatic embryos were induced on callus derived from the petal explants with all the studied genotypes. Addition of PVP (300 mg/l) in the induction medium improved the rate of somatic embryos of the genotypes C1 and C14. The improvement of responses to somatic embryogenesis in reducing the rate of browning of cultures will allow a mass production of the high-yield cocoa genotypes

Propagation of Garcinia kola (Heckel) by stem and root cutting

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