The researchers generated Osmtl knockout mutants in the hybrid rice variety ChunYou84 (CY84). The mutant showed higher rates of seed abortion under self-pollination and produced more seeds with a viable embryo but lacking endosperm (termed Em-en seeds) than the wild-type (WT) CY84 (5% versus 0.2%). These Em-en seeds could germinate, although at a lower rate than intact Em-En seeds containing both embryo and endosperm (25.3% versus 85.2%).