Effect of exogenous phytohormones on the evolution of certain biochemical parameters during the somatic embryogenesis of Ricinodendron heudelotii Baill

To introduce Ricinodendron heudelotii (Euphorbiacae) into agro-systems, plantlets with a taproot system can be obtained by in vitro somatic embryogenesis. We studied the effect of some exogenous phytohormones on certain biochemical parameters characteristic of the species' somatic embryogenesis. Somatic calli and embryos were induced by culture of leaf fragments on a basic medium enriched by (1, 2 or 3) mg 2,4-D/L super(-1) or by combinations of [2,4-D / kinetin] or [2,4-D / BAP] implying hormones with various concentrations. Extractions and analyses of total sugars, phenols, total proteins and peroxidase activity were carried out after (30, 50 and 70) d of callus development. After 30 d of culture, the best percentages of explants forming calli varied from 72, 1% to 100% according to the phytohormones used. After 50 d, these calli formed globular accumulations of cells in division (embryonic nodules). After 70 d, 17, 4% among the calli differentiated multiform somatic embryos in the presence of 3 mg 2,4-D/ L super(-1); 23, 1%, in the presence of [1 mg 2, 4-D/L super(-1) + 1 mg kinetin L super(-1)] and 27, 6%, in the presence of [1 mg 2,4-D/L super(-1) + 2 mg BAP/L super(-1)]. The sugar content was highest at 30 d (callus formation) and 50 d (embryonic nodule formation on calli), whereas the phenol and protein contents, and the peroxidase activity, were higher at 70 d (somatic embryo differentiation on calli). Following the example of what occurs in other plant species, in R. heudelotii, the exogenous phytohormones would operate in the metabolism control of the biochemical parameters implied in the somatic embryo formation and development.Original Abstract: Resume -- Introduction. Pour introduire Ricinodendron heudelotii (Euphorbiacee) dans les agrosystemes, des plantules ayant un systeme racinaire pivotant peuvent etre produites par embryogenese somatique in vitro. Nous avons etudie l'effet de quelques phytohormones exogenes sur certains parametres biochimiques caracteristiques de l'embryogenese somatique de l'espece. Materiel et methodes. Des cals et des embryons somatiques ont ete induits par culture de fragments de feuilles sur un milieu de base enrichi en (1, 2 ou 3) mg 2,4-D/L super(-1) ou de combi-naisons [2,4-D / kinetine] ou [2,4-D / BAP] impliquant differentes concentrations des hormones. Les extractions et analyses des sucres totaux, phenols, proteines totales et activite des peroxydases ont ete faites apres (30, 50 et 70) j de developpement des