WUS binds the <i>GRP23</i> promoter directly to activate its expression.

<p>(A) qRT-PCR analysis of <i>GRP23</i> expression in Ws, <i>sef</i>, L<i>er</i> and <i>wus-1</i>. Data are means ± SD (n = 3). (B) qRT-PCR analysis of <i>GRP23</i> expression in 14-day-old <i>pga6</i> seedlings after inducing with 17-β-estradiol for 1, 3, 5 and 7 hours. Data are means ± SD (n = 3). (C) Transient expression assay in <i>Arabidopsis</i> protoplasts. The promoters of <i>GRP23</i> and <i>CLV3</i> were used to drive the <i>luciferase</i> (LUC) reporter gene. <i>WUS:GFP</i> fusion driven by the 35S promoter was used as effector. LUC activity was assayed after transformation. Data are means ± SD (n = 3). (D) ChIP assay of 7-day-old seedlings to show WUS-binding regions in <i>GRP23</i> promoter. Regions i, -784 to -660; ii, -311 to -211; iii, -195 to -95. Data are means ± SD (n = 3). (E) EMSA of WUS binding the <i>GRP23</i> promoter <i>in </i><i>vitro</i>. The unlabeled double-strands probe (wt) and unlabeled mutant probe (mut) were used for competitive inhibition with 200X, 400X, or 800X molar excess.