osgen1 plants exhibit normal vegetative growth but severe fertility defects. A, Wild-type and osgen1 plants after heading. B, Wild-type and osgen1 spikelets before anthesis. C, Wild-type and osgen1 spikelets after removal of the palea and lemma. D and E, I2-KI staining of the pollen grains within the anther of the wild type (D) and osgen1 (E). Bars = 5 cm in A, 1 mm in B and C, and 100 μm in D and E.