| Abstract: | Embryos and nutritive tissues in ungerminated Yucca seeds of 4 species contain many spherical bodies which stain positively for proteins. Two distinct morphological types were observed at both the light and electron microscope levels. A meshwork-type consists of electron-dense and electron-transparent regions in which are embedded slightly birefringent inclusions. The second type, named the core-type, consists of a core surrounded by a matrix in which the inclusions are embedded. A single unit membrane surrounds each protein body. Both types are present in the embryo while only the core-type protein body appears in the surrounding nutritive tissue (perisperm). All regions in each of the two protein body types, except the inclusions, stain histochemically for proteins. Seeds were planted at 2-day intervals and allowed to germinate through 14 days. As germination commences (day 0) protein bodies in the embryo begin to break down. By day 4 the bodies are depleted in embryos of 3 of the 4 species. About day 4, protein bodies in perisperm surrounding the embryo begin to break down and this process continues outward to the seed coat until day 14 when all seed proteins have disappeared. During germination the protein bodies in the embryo and perisperm of 3 species coalesce and then undergo breakdown. In a fourth species, there is no appreciable increase in size of the bodies, but an erosion of the periphery and possibly internally as well takes place, followed by ultimate dissolution. |
