Histology of somatic embryogenesis induced in embryos of mature seeds of the apomictic Urochloa brizantha

The objective of this work was to describe the process of somatic embryogenesis in Urochloa brizantha cv. Marandu (Syn. Brachiaria brizantha cv. Marandu) and to provide support for the improvement of tissue culture and genetic transformation methods. Embryogenic calli were obtained by induction in embryos isolated from mature seeds, and cultivated in vitro in culture medium containing 2,4-dichlorophenoxyacetic acid, 6-benzylaminopurine and hydrolyzed casein. Plantlets were regenerated from the embryogenic calli in the presence of naphthaleneacetic acid and kinetin. This process was described by morphological observations of serial semithin sections of tissues fixed along the regeneration process in FAA (40% formaldehyde: acetic acid: 50% ethanol, at 5:5:90 v/v/v), using light microscopy. Seed embryos of U. brizantha cv. Marandu do not have epiblast and are classified as Panicum-type. Under in vitro culture conditions, embryogenic calli and somatic embryos of U. brizantha cv. Marandu develop from meristematic cells of the scutellum.