Early Endosperm, Embryo, and Ovule Development in Glycine max (L.) Merr.

Abstract

Anatomical and ultrastructural aspects of soybean embryo, endosperm, and ovule development are described for the zygote to late heart-shaped embryo stages (0-35 d postfertilization). Nucellar cells subtending the degenerative synergid break down, allowing for pollen tube passage to this synergid. In 15 of 17 ovules studied, the degenerative synergid occupies a position abfunicular to the zygote. The inner integument differentiates into the endothelium and exterior layers of thick-walled cells at the globular embryo stage. The endothelium has a cuticle on its inner surface that begins to fragment at the onset of endosperm cellularization. Cellularization of the free-nuclear endosperm is initiated at the globular embryo stage by the formation of anticlinal ingrowths of the central cell wall. These walls fuse to form cylinders open to the central cell. Uninucleate cells are formed within the bases of the cylinders as periclinal walls are laid down. These latter walls are formed in the presence or absence of ...