File:Phylogenetic tree of CAP1 and related proteins in plants.jpg

Phenotype and germinability of pollen grains affected by a cap1 mutation. Pollen grains were isolated from wild-type (A, C, and E) and heterozygous (+/–) cap1 (B, D, and F–H) mutant plants, and pollen germinability was examined in vitro (I and J). Pollen grains were stained with IKI solution to visualize starch granules (A and B), with hematoxylin solution to identify nuclei (C and D), with Alexander’s solution to test viability (E and F), and with calcofluor white solution to visualize cell wall (G and H). Wild-type pollen grains fully accumulated starch granules (A) and contained two sperm nuclei with condensed chromatin (C, arrowheads) and one vegetative nucleus with diffused chromatin (C, arrow). In Alexander staining, viable pollen grains were purple (E), whereas mutant grains of the cap1 heterozygous (+/–) plant were stained blue (F, arrows). No/few starch granules (B) or cytoplasmic materials (F) were detected, and neither nucleus nor cell wall was observed (G and H) in mutant pollen grains (arrows). Pollen germination of cap1 on the germination medium is shown in I. Arrowheads in I indicate germinating pollen tubes. Arrows in B, D, F–H, and I indicate collapsed mutant pollen grains. The pollen germination rates of cap1 (+/–) and cv Nipponbare are shown in J. Error bars indicate sd. Bars = 100 µm (A, B, and E–H), 50 µm (C and D), and 200 µm (I).