Development of wild-type and gpt2 plants on media containing ABA. Seeds were sterilized as for seedling development assays and sown into half-strength MS or half-strength MS medium with 1–10 μm ABA. After a 2-day stratification at 4 °C in the dark, plants were transferred to 8 h day/16 h night at an irradiance of 100 μmol m⁻² s⁻¹ white fluorescent light for 7 days. Germination was scored as the emergence of the radicle (and subsequent growth). (A–D) Representative plates showing wild-type on half-strength MS (A), gpt2 on half-strength MS (B), wild-type on half-strength MS with 10 μm ABA (C) and gpt2 on half-strength MS with 10 μm ABA (D). Inset figures show five representative seeds/seedlings for each line/treatment. Black scale bars = 20 mm, white scale bars = 5 mm. (E) Mean percentage germination for each line/treatment on different concentrations of ABA. Each measurement represents the mean of at least three replicate plates, each plate containing at least 150 seeds. Error bars represent ±1 s.e.