Movie S5.

z-stack of the aborting seed from a +/umps-1 plant, shown in Fig. 6M, when embryos in green seeds from the same silique were at the late globular-transition stage. The embryo had arrested at the elongated zygote/1-cell stage. Endosperm development had ceased after the first mitotic divisions and the endosperm nuclei appear to be enlarged. The chalazal cyst failed to develop. The seed was Feulgen stained and imaged under a confocal microscope. Optical sections were acquired at 0.5-nm intervals from the top of the seed coat. The movie was created from a z-stack of 44 optical sections. Scale bar is 25 μm.