Movie S3.

z-stack of the aborting seed from a +/rpi3-2 plant, shown in Fig. 6E, when embryos in green seeds from the same silique were at the torpedo stage. The embryo had arrested development at the 8-cell/dermatogen stage of development. The peripheral endosperm has fewer nuclei than in wild-type seeds of comparable developmental stage; the nuclei are unevenly distributed along the anterior-posterior axis. 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, covering the seed cavity. The movie was created from a z-stack of 19 optical sections. Scale bar is 15 μm.