Fig. 5

The early embryo development of V. planifolia. a A mature embryo sac showing the egg apparatus, including the egg cell (arrow) and two synergids (arrowheads). The outer seed coat (OS) was elongating and had not enclosed the inner seed coat (IS). b At 30 DAP, after fertilization, zygote (arrow) had a dense cytoplasm, and the degenerated antipodal cells (arrowhead) at the chalazal end were densely stained. In this species, the endosperm failed to develop, and a degenerated endosperm nucleus (double arrowhead) could be observed. c Light micrograph showing a three-celled proembryo (arrow), and a degenerated endosperm nucleus (arrowhead) stayed beside the zygote. d By 45 DAP, an anticlinal division (arrow) occurred in the outmost cell layer, resulting in the formation of the globular-shape embryo. e Light micrograph showing an early globular embryo with an additional anticlinal division (arrow). This species did not have a distinct suspensor during embryo development. f Light micrograph showing a longitudinal section through a globular embryo at 60 DAP. The outer most layer of outer seed coat (OS) became lignified. Scale bar = 100 μm