Figure 4.

GA2ox2 Regulates MC Formation Cell Non-autonomously

(A) Relative expression of GA2ox2 in 5 and 8 dpg old WT plants. N = 3.

(B and C) Confocal images of meristems of Q0990 (B) and Q0990>>GA2ox2 plants at 5 dpg (C). Scale bars, 50 μm; white arrowhead indicates MC formative asymmetric division; blue arrowheads indicate the CEI.

(D) Histogram depicting the percentage of MC formation in Q0990 and Q0990>>Ga2ox2 at 5 dpg. n = 20, N = 3.

(A and D) n = 3; Student’s t test (^∗∗p < 0.01; ^∗∗∗p < 0.005). Error bars: SD.

(E) Model: PHB levels increase between 5 and 8 dpg, resulting in increased GA2ox2 expression. Increased GA2ox2 levels promote the degradation of GAs in the vasculature, stabilizing GAI protein. GAI directs the accumulation of CYCD6;1 in the endodermis, promoting MC formation. Decrease levels of GAs after 5 dpg dampens SHR levels that regulate miR165 and 166 and SCL3 that in turn attenuate PHB expression and GAI activity, respectively. Orange, cortex (C); cyan, endodermis (E); yellow, middle cortex (MC); green, cortex/endodermis initial (CEI); blue, periclinally dividing cells (dashed line). Yellow arrow indicates the CYCD6;1 switch.

See also Figure S4.