<i>KS1</i> is expressed in the root tip and has a role in GA-mediated elongation and proliferation of root meristem cells.

<p>(A) RNA <i>in situ</i> hybridizations with an anti-sense probe (left panel) and a sense probe (right panel) showing <i>KS1</i> mRNA accumulation in the root tip. Scale bar = 100 μm. (B) Phenotype of 4-day-old WT and <i>ks1</i> seedlings. Scale bar = 5 mm. (C-F) Median longitudinal sections through root tips of 4-day-old WT (C, D) and <i>ks1</i> (E, F) seedlings. Arrowheads indicate the proximal end of the root meristem. Insets are an enlargement of the regions at the proximal end of the root meristem. Red dotted line marks the 4^th cortical layer selected for the quantification analysis. (D, F) Boxed regions in (C, E). Scale bar = 50 μm. (G-H) Median longitudinal view of EdU-labelled cells in the root meristem of WT (G) and <i>ks1</i> (H) seedlings. Scale bar = 50 μm. (I) Root meristem size of 4-day-old WT and <i>ks1</i> seedlings treated with mock or 10 μM GA₃. (J) Cell number in the root meristem of 4-day-old WT and <i>ks1</i> seedlings treated with mock or 10 μM GA₃. (K) Average cell length in the root meristem of 4-day-old WT and <i>ks1</i> seedlings treated with mock or 10 μM GA₃. Error bars in (I) to (K) represent SD (<i>n</i> = 15). **, <i>P</i> < 0.01, <i>t</i>-test; <i>*</i>, <i>P</i> < 0.05, <i>t</i>-test.