Table 5.
Functional megaspore (FM) development in WT and ubc22-1 mutants
| Line | Total number | Typical FM (Type I) | Visible FM with abnormalities (Type II) | FM not observable (Type III) |
|---|---|---|---|---|
| WT (%) |
114 (100) |
99 (86.8) |
10 (8.8) |
5 (4.4) |
|
ubc22-1
(%) |
123 (100) |
34 (27.6) |
43 (35.0) |
46 (37.5) |
Flowering buds (the fifth bud from the newly opened flower) were dissected, prepared, and then observed under a microscope equipped with DIC optics. Ovules at the functional megaspore (FM) stage (with the inner integument near, but below, the top of the nucellus) were included in the analysis. Three types of ovules were observed. Type I (normal): A typical FM had one prominent nucleus with a round shape and clear nuclear–cytoplasm boundary. Type II: The FM was visible. However, the nuclear–cytoplasm boundary was not clear, and/or the nucleoplasm appeared to be disorganized. In the ubc22-1 mutant, the FM was often barely visible (see Fig. 5E, F). Type III: No FM could be observed.