In cotton, factors such as carbon sources, hormonal combination, and type of explant influence the responses to callus induction. In this study callus induction was optimized to get high-frequency callus in cotton. Different carbon sources were tested, and among them, glucose at 3% was found to be the best carbohydrate in callus induction. Culture medium supplemented with 2,4-D (0.1 mg.L-1) and KIN (0.5 mg.L-1) gave a high callogenesis response, unlike other hormonal combinations. With explants, hypocotyl (72.93%) appeared easier to induce callus than cotyledon (48.75%) following root (37.5%). So, carbone sources, hormone, and their concentration affect significantly callus induction. The highest frequency of callus induction was then observed when hypocotyl explants were cultured on medium supplemented with 0.1 mg.L-1 of 2,4-D in combination with 0.5 mg.L-1 of KIN and 3% glucose. The induced-callus obtained were friable and of high quality. The other types of combinations resulted in the formation of compact callus with sometimes roots emerging from it. The present study may provide an efficient protocol to improve the callogenesis responses by adjusting the carbohydrates, the hormonal regime, and the type of explant to be cultured for a high-frequency callus induction of the Y331B-R5 cotton cultivar.

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The objective of this study is to show the real impact of methyl jasmonate and ethephon in combination on the production of phenolic compounds in cultivar R405-2000 of the cotton plant Gossypium hirsutum. As well, cotton plants were treated in the field by methyl jasmonate (MeJA), ethephon (ETH) and the association of methyl jasmonate and ethephon (MeJA + ETH). The effect of these treatments was appreciated thanks to a qualitative analysis of total phenols by High Performance Liquid Chromatography. The results showed that ethephon, the metabolic precursor of ethylene, has properties identical to those of MeJA. However, the treatment of cotton leaves with ethephon induces less phenolic compounds than MeJA. On the other hand, the co-treatment of the leaves with MeJA and ethephon leads to an induction of phenolic compounds, which accumulate in greater quantities in the plant the phenols synthesized are more important with an activation of the biosynthetic pathway of stilbenoids because trans-resveratrol and transpiceide, two compounds belonging to the group of stilbenoids were synthesized de novo by the joint application of MeJA and ethephon on cotton leaves when they could not be synthesized when these two elicitors are applied alone.