Figure 4.

sdg2-1 Shows Severe Defects in Ovule and Female Gametophyte Development.

(A) and (B) DIC images of ovule primordia in Col and sdg2-1, respectively. Arrows indicate archesporial/megasporogenous cells.

(C) to (E) DIC images of a Col ovule at the two-nucleate embryo sac stage (C) and of sdg2-1 ovules at later developmental stages ([D] and [E]). Note the absence of an obvious embryo sac and the disproportionate nucellus and integument proliferation in sdg2-1 ovules. Arrows indicate a two-nucleate embryo sac in Col (C) and abnormal nucellus (nu), inner integument (ii), and outer integument (oi) in sdg2-1 (D).

(F) to (I) Three-dimensional reconstruction images of confocal sections of Col (F) and sdg2-1 ([G] to [I]) mature ovules. In the Col ovule, arrows indicate the following: ch, chalazal region containing three degenerating antipodal cell nuclei; cn, diploid central cell nucleus; en, egg cell nucleus; and sn, two synergic cell nuclei at the micropylar end. In sdg2-1 ovules, arrows indicate the micropylar end with signs of degenerating cells visible as brightly fluorescent abnormal structures.

Bars = 10 μm.