Fig. 1: Phenotype comparison between the WT and Ossrf8 mutant.

a, b In vitro pollen germination assays of WT and the Ossrf8. The black arrows indicate pollen tubes. Phenotypes in (a, b) were observed at least three times independently with similar results. Scale bars, 100 μm. c, d, SEM micrographs show that there is no aperture on the Ossrf8 pollen. The black arrow indicates the aperture. Three plants (≥30 pollen grains per plant) were imaged in (c, d) with similar results. Scale bars, 10 μm. e–h TEM images of mature pollen. f and (h) represent enlarged views of the dashed square, respectively. ≥10 pollen grains were imaged in (e, g) with similar results. Scale bars, 10 μm. i–l Confocal images of tetrads stained by Calcofluor White (blue, callose wall) and Cell Mask Deep Red (red, membranous structures). APMP (dashed square) can be observed in wild-type tetrads, but not in mutant tetrads. j and l represent enlarged views of the dashed square, respectively. The red dotted lines indicate the boundary of the plasma membrane and the blue dotted lines indicate the outer boundary of the callose wall of microspore at the tetrad stage. Experiments in (I, k) were repeated three times with similar results. Scale bars, 10 μm in (i, k), 2 μm in (j, l).