THE HISTOLOGICAL DEVELOPMENT OF THE REGENERATIVE TISSUE DERIVED FROM CULTURED IMMATURE EMBRYOS OF WHEAT (TRITICUM-AESTIVUM L)

Histological studies were conducted on the embryogenic tissue of wheat (Triticum aestivum L.), using primary, subcultured and differentiating callus derived from the scutellum and epiblast of immature embryos. Structures with multiple strata were observed in the late stages of callus induction and on subcultured callus; these were characterized by a middle stratum of ground meristematic tissue with a shoot-forming stratum above and a stratum of large cells below. The shoot-forming protuberances appearing on the differentiating callus were morphologically similar to those observed on subcultured and primary callus and also to the expanding shoot meristem of the cultured embryos. This similarity suggests the continuity of the pre-existing shoot forming tissue during culture in vitro. Typical embryoids have been previously reported on both scutellum and epiblast callus hence this callus could be described as embryogenic. However, organogenesis also occured on the callus as some of the protuberances had a vascular connection to the basal callus. Some of the regenerative outgrowths on the callus were broadly based and were not of single cell origin. © 1990.