Pollen grains of the 4n plants generated from the 2n lines with reduced levels of <i>INP1</i> expression and shortened apertures develop four shortened apertures.

<p>(A) Schematic description of the experiment to distinguish between possible mechanisms involved in specifying aperture number. Tetraploid plants generated from the diploid short-aperture line by colchicine treatment are expected to produce 2n pollen with 3 longer apertures if INP1 level is the factor that determines the number of apertures. 2n pollen with 4 short apertures is expected if other factors (e.g. levels of another gene or changes in cell geometry) dictate aperture number. (B-C’) An <i>INP1pr</i>::<i>INP1-myc; inp1 S</i> line produces three short apertures in haploid pollen (B-B’) and four short apertures in diploid pollen (C-C’). An <i>INP1pr</i>::<i>INP1-myc; inp1 M</i> line produces three medium-size apertures in haploid pollen (D-D’) and four medium-size apertures in diploid pollen (E-E’). Apertures are indicated by arrowheads. Scale bars = 10 μm.