The dsptp1 mutant shows altered expression of ABA-regulated genes under osmotic stress. Expression levels of several genes in response to ABA signalling were analysed by qRT-PCR (A–D): ABI1 (A), ABI3 (B), ABI4 (C), and ABI5 (D). Total RNA was isolated from 15-d-old WT and dsptp1 seedlings treated with 385mM mannitol for the times indicated. In all experiments, the expression of the constitutive Actin2 gene was used as the control. Three replicates were made for each treatment with similar results. Values are mean ± SE of three different experiments. Means denoted by the same letter do not significantly differ at P < 0.05 according to Duncan’s multiple range test.