The effect of methyl jasmonate (MeJA) sprayed on cotton healthy leaves was evaluated in terms of inherent bioactive chemicals induction. The total phenolic content significantly increased after MeJA 5.0 mM treatments compared to the other tested concentrations (0; 2.5; 10; 15; 20 mM). Among the eleven phenolic compounds which were found except for ferulic acid, gossypetin, gossypol, 3-p-coumaroylquinic acid, and piceatannol were identified as major phenolic constituents of cotton. Their content also significantly increased after the MeJA treatment. In addition, gossypol increased 64 times compared to the control, in the 5.0 mM MeJA treatment. Furthermore, cichoric acid, chlorogenic acid, and pterostilbene are synthesizedde novoin leaves of MeJA-treated plant. Treatment of cotton leaves with MeJA 5.0 mM followed 72 h of incubation hampered the expression ofFusariumwilt caused byFusarium oxysporium f. sp. vasinfectum(FOV). MeJA efficiency was concentration and incubation time dependent. Disease severity on MeJA-treated leaves was significantly lower as compared to the control. Therefore, the high content of gossypetin, gossypol, 3-p-coumaroylquinic acid, ferulic acid, and piceatannol and the presence of cichoric acid, chlorogenic acid, and pterostilbene in plants treated with MeJA, contrary to the control, are essential to equip the cotton compounds with defences or phytoalexins against FOV.

Generating somatic embryos from the inner teguments of hevea seeds is difficult. Like other ligneous plants, the rubber-tree is generally considered to be recalcitrant with regard to somatic embryogenesis. In this study, the ability of callus from inner integument explants to develop embryogenic callus lines was highlighted. Combination of 2,4-dichlorophenoxyacetic acid (2,4-D/KT) (9 µM/3.375 µM) revealed the positive effect of the 2,4-D on callogenesis and somatic embryogenesis from the inner integument of the seed of immature fruit. The rate of embryogenic calli of about 50% obtained, suggested that 2,4-D has a similar effect as 3,4-dichlorophenoxy acetic acid (3,4-D). So, although 2,4-D is rarely used as a hormone in biotechnology of rubber, its positive influence on callus induction and somatic embryo development shows that it is an alternative to 3,4-D which is commonly used. Optimal combinations of 2,4-D/thidiazuron (TDZ) (9 µM/34.2 nM) produced abnormal embryos at lower rates (approximately 5%) than the optimal combination of 2,4-D/KT.

A highly reproducible and efficient in vitro shoot regeneration system was developed for two banana varieties (FHIA-21 and PITA-3) using shoot tip as explant. Shoot tip was inoculated onto Murashige and Skoog (MS, 1962) medium supplemented with cytokinins [benzylaminopurine (BAP), kinetin (Kin) and 2-isopentenyl (2-iP)] and additives [Adenine sulphate (Ads), spermidine (Spd) and casein hydrolysate (CH)] for shoot multiplication. In all varieties, the maximum number of shoots and shoot length was obtained with 3 and 4 mg/L BAP, respectively. This rate was further enhanced by adding Ads (25 mg/L), CH (25 or 50 mg/L) and Spd (100 or 200 mg/L). In vitro raised shoots were successfully rooted on 1 mg/L 2-iP in combination with 0.5 mg/L naphthaleneacetic acid (NAA). Rooting was significantly enhanced by adding casein hydrolysate (25 or 50 mg/L). The well rooted plantlets were successfully acclimatized on different substrates (compost, forest soil, sand, forest soil + sawdust from dead tree and sand + sawdust from dead tree). The compost substrate was found to be preferable. Finally, after one month in the greenhouse, the hardened plants were transfered to the field environment for utmost survivability.

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 vitro

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