Effect of the <i>rsw7-lph</i> mutation on cellularization of the male gametophyte and endosperm.

<p>(<b>a</b>): Pollen produced by <i>rsw7-lph</i>/+ plants; scanning electron micrograph showing a mixture of normal (star) and shriveled or collapsed grains; scale bar equals 10 μm. (<b>b–e</b>): Cell division defects of <i>rsw-lph</i> male gametophytes. DAPI staining of normal pollen (<b>b</b>) reveals two small, brightly staining sperm cell nuclei and the large, less brightly staining nucleus of the vegetative cell; pollen of <i>rsw7-lph</i>/+ plants is frequently mono-nucleate (<b>c</b>), bi-nucleate (<b>d</b>), or collapsed with no detectable DNA (<b>e</b>); scale bar in (<b>e</b>) equals 10 μm. (<b>f, g</b>): Absence of a cellularized endosperm in <i>rsw-lph</i> seed. Confocal micrographs of Schiff-stained seed show the presence of cell walls in the endosperm of seed containing wild type embryos (<b>f</b>) but not in seed containing mutant embryos (<b>g</b>); scale bar in (<b>g</b>) equals 50 μm.