Fig. 7

Light micrographs of embryo development of G. nantoensis. a Light micrograph of the zygote after fertilization at 8 DAP. The zygote (arrow) is highly polarized with a chalazally located nucleus and a prominent vacuole occupying the micropylar end. The polar-chalazal complex (arrowhead) includes the chalazal nuclei and the polar nuclei, but the endosperm eventually fails to develop. A number of starch grains (double arrowhead) could be seen in the seed coat. Scale bar 30 μm. b The first cell division of the zygote is unequal and results in the formation of a smaller terminal cell and a larger basal cell. Several tiny starch grains (arrow) have appeared within the cytoplasm. Scale bar 30 μm. c Light micrograph showing a three-celled embryo. The basal cell of the three-celled embryo will differentiate into the suspensor. Scale bar 30 μm. d Light micrograph showing a proembryo with a highly vacuolated suspensor cell (S). Scale bar 30 μm. e Light micrograph showing an early globular embryo. The size of starch grains (arrow) within the embryo proper becomes larger. Scale bar 30 μm. f A longitudinal section through a developing globular embryo. Large starch grains (arrow) are abundant and tend to congregate around the nucleus. The suspensor cell (S). Scale bar 30 μm. g As the seed approaches maturity, the cell division within embryo proper has ceased. At this stage, starch grains (arrow) are prominent within the embryo cells. The suspensor cell (S) has reduced its size and begins to degenerate. Scale bar 30 μm. h A longitudinal section through a mature seed at 20 DAP. The embryo has the smaller cells near the chalazal end and the larger cells in the micropylar end. At this stage, the starch grains have disappeared and numerous tiny protein bodies (arrow) have accumulated within the embryo proper. In this preparation, the lipid cannot be preserved, however the spaces between the protein bodies could be the storage lipid bodies. At maturity, the suspensor has degenerated and the embryo proper is enveloped by a shriveled seed coat. Scale bar 30 μm