Figure 4.

GA Levels Differentially Modulate Leaf Area after Cold Stress in 35S:GRF5.

(A) Representative first true leaves of wild-type seedlings (Col) and of seedlings of transgenic lines overexpressing GRF5 (35S:GRF5), which is not targeted by miRNA396, or the GRF-targeting miRNA396b (35S:miR396b). Seedlings were germinated for 6 d on half strenth MS (without mock or hormone treatment) at ambient temperature. Seedlings were then transferred for 7 d to half strenth MS containing 10 µM GA3 (GA) or 0.1 µM PAC (PAC) or a corresponding mock solution for 7 d at 21°C. In a parallel setup, the seedlings were first exposed to a 7-d 4°C cold stress treatment, which fully arrests plant growth, followed by a 7-d recovery period at 21°C.

(B) Scatterplots of individual measurements (dots) of leaf areas from seedlings shown in (A). Also shown are means and sd of 16 seedlings. The dotted lines mark the means of the mock-treated wild-type sample and serve for orientation. Data sets with no statistical difference after ANOVA and Tukey’s HSD posthoc test fall into one group and are labeled with identical letters.