C18 plants, overexpressing OsPP2C09, are hypersensitive to osmotic stress. (A), A8 and C18 plants transferred after the two-leaf stage to half-strength MS medium containing the indicated mannitol concentrations for 8 d. (B), Shoot lengths were measured, with six or more seedlings per replicate. Relative shoot length for A8 and C18 seedlings, normalized to mock control (0 mM mannitol). The values are means ± SD (n = 3). The experiment was repeated three times with similar results. Two-way ANOVA was performed comparing with A8 plants (****: p < 0.0001, **: p < 0.01, *: p < 0.05, -: not significant). (C), Relative transcript levels of OsPP2C09 in C18 seedlings. All values were determined by RT-qPCR and normalized to UBIQUTIN5 before normalization to relative transcript levels in Dong-Jin (DJ), shown as mean of relative quantity and SD. One-way ANOVA was performed (****: p < 0.0001).