Trends in Biosciences

This study was carried out to investigate the morphological and anatomical aspects of callogenesis and somatic embryogenesis in date palm (Phoenix dactylifera L.). Shoot tip explants excised from young offshoots were cultured on MS medium with 2,4-D, BA and 2-ip. Somatic embryogenesis was produced by transferring the calli produced on BA medium. Sectioning of specimens was carried out using the Somatic embryos, callus tissue and its differentiating structures. The sections were stained with safranin and fast green. Histological examination of swollen explants, after eight weeks (60 days) showed formation of new parenchymatous cells resulting into swelling of explants. The new cells were small, packed densely and appeared in concentric layers. Around 130–140 days, when very small amount of callus was seen first, the sections revealed formation of periclinal concentric layers of cells from the peripheral region of explants. At this stage, cells surrounding the callus cells looked empty. Inner region of callus exhibited a core region composed of densely packed meristematic cells with cortical zone surrounded by layer cells 1–2 vacuoles. This region was surrounded by loosely arranged parenchymatous cells, which constituted the visible callus. Small individualized embryogenic masses and globular embryos were observed embedded in degenerating parenchyma, soon they matured into individual globular embryos surrounded by an epidermal cell layer. Longitudinal section of further developed embryos displayed a well differentiated vascular system along the cotyledon and a fully organized shoot apex.