Development and cytochemistry of the embryo suspensor in Sedum

摘要

The development of the suspensor in Sedum acre L. and S. hispanicum L. was investigated using cytochemical methods and light rnicroscopy. After the first division of the zygote, two cells of unequal size are formed: the large basal cell and the smaller apical one. The basal cell grows enormously and produces haustorial branches invading ovular tissues. The mature differentiated suspensor consists of a large basal cell and 3-4 chalazal cells. Proteins, insoluble polysaccharides, nucleic acids and lipids are localized in the suspensor during different phases of embryo growth. Cytochemical tests showed the presence of high amounts of macromolecules in the suspensor cells, especially during the globular and torpedo-shaped stages of embryo development. The present data indicate that in Sedum the suspensor is involved mainly in absorption and transport of metabolites from the ovular tissues to the developing embryo proper.