Embryogenèse somatique du cocotier (Cocos nucifera L.) à partir d'explants foliaires: étude histologique

Abstract

Histological studies were carried out at different stages of somatic embryogenesis of coconut (Cocos nucifera L.) from leaf explants. The primary formations resulted from mitotic divisions of perivascular cells. Differentiation of a cambium-like layer insured the growth of nodular calluses. The root origin of some formations was observed. Embryogenic structures appeared on some nodular calluses maintained in culture; initially they were highly meristematic and often developed an epidermis and divided. Then embryo-like formations could be obtained after fragmentation of the cambium-like layer producing meristematic areas. However, modifications of this scheme could be observed: (i) Embryos rapidly developed from a primary callus, and from these embryos, a secondary embryogenesis was induced leading, at the root pole, to a clump of somatic embryos. One of the latter developed a shoot and roots; the regenerated plant was then transferred to the field. (ii) Secondary granulous calluses producing larger quantities of embryogenic structures were formed. This material should prove useful for mastering the technique of developing embryogenic structures. Key words: Cocos nucifera L., histology, somatic embryogenesis, foliar explants.