Histology of Somatic Embryogenesis from Leaf Explants of the Oil Palm Elaeis guineensis

Histological analysis was carried out during the sequence of events which lead to the obtaining of somatic embryos of oil palm. Calluses from the division of perivascular cells formed at the veins of young leaf explants. Subsequent proliferation of histologically similar nodules was by means of a cambium-like zone. Under certain conditions these calluses consisted almost entirely of meristematic cells. They then differentiated rapidly: the cambium-like zone fragmented, leading to protuberance in which the cells divide rapidly; epidermal structures were formed, with a network of procambial strands, and synthesis of storage lipids accompanied the formation of these embryo-like structures which developed into clumps of true somatic embryos, each with a shoot apex and a root apex. Other structures frequently observed during in vitro culture are also described and show that alternate pathways do exist. The structure and evolution of somatic embryos are compared to those of zygotic embryos. Storage lipids emerge as an early tracer of the satisfactory development of tissue towards somatic embryogenesis.