Figure 4.

Functional redundancy of TZF1 and TZF4 in mediating Glc-TOR signaling. (A, B) The tzf1 tzf4 double mutant displays a modest but significant synergistic enhancement of Glc-TOR signaling response. Red arrows indicate the hypocotyl and root junctions. DAG, days after germination; D, day; Mock, sugar-free; Man, mannitol; Glc, glucose; Suc, sucrose; scale bars: 0.5 cm. Data represent mean ± s.e.m. of 16 plants. The result was shown from one of the three biological replicates with similar results. Root lengths were measured by using ImageJ. (C) DIC imaging of root meristem zones. Scale bar: 50 μm. The blue arrow indicates the root quiescent cells, and the red arrow indicates the transition between root meristem zone and elongation zone. (D) Quantitative analysis of the root meristem size in (C). Data represent mean ± s.e.m. of 16 plants. The result was shown from one of three independent experiments with similar results. The root meristem size was measured by using ImageJ. Different letters in (B) and (D) indicate significant differences at P < 0.05 by one-way ANOVA. Uppercase letters compared with each other in 15 mM Glc treatment condition, and lowercase letters compared with each other in 15 mM Suc treatment condition. (E) TOR expression level is significantly enhanced in tzf1 tzf4. The total RNA was isolated from the roots of 6-day-old seedlings grown in half-strength liquid MS medium without sugar in 12-h weak light (13 μmol m⁻¹ s⁻¹) /12-h dark cycles at 22°C and harvested at ZT6. The gene expression level was normalized by the geometric mean of ACT2 and TUB4 expression. Data represent mean ± s.e.m. of three biological replicates. The asterisks indicate significant difference at P < 0.01 (**) by t-test.