Figure 12.

Tapetal PCD Occurs Prematurely in the undead Mutant.

Confocal microscopy of DNA fragmentation detected using the TUNEL assay in 8-μm sections of siRNA undead anthers. TUNEL-positive signal is indicated by the green fluorescence of fluorescein. Grayfield ([A], [C], and [E]) and propidium iodide counterstain ([B], [D], and [F]) of stage 9 ([A] and [B]), 11 ([C] and [D]), and 12 anthers ([E] and [F]). TUNEL-positive signals are strongly present in stage 9 undead tapetum, suggesting that advanced PCD degeneration has occurred (arrows). TUNEL signal is present in collapsing microspores at stages 11 and 12. Bars = 25 μm.