Figure 3.

Embryo and endosperm proliferation in wild-type and mutant Arabidopsis plants. Seeds were cleared and visualized with Nomarski optics, and the number of embryo cells (A) and endosperm nuclei (B) were counted. The average number of cells or nuclei (±SD, n = 10) is shown for each time point, except the number of cells in only a single wild-type embryo at 9 DAP was determined. Wild-type embryos were at the globular stage at 2 DAP, early heart stage at 4 DAP, early torpedo stage at 5 DAP, and mature stage at 9 DAP. ○, wild-type; ■, f644 mutant; ⋄, 7523 mutant. 7523 is a recessive zygotic embryo defective mutation in the Wassilewskja genetic background that arrests embryo development at the early heart stage.