Fig. 1. GUS expression in the 826 line is confined to cell division foci. (A) Expression of the GUS gene in 826 seedlings is found in the apical regions of both shoot and root. (B) GUS activity is found in the SAM and leaf primordia, but not the surrounding tissues. (C) The division zone of the main root, but not the quiescent center (QC), is marked by strong GUS expression. (D) Lateral root primordia are marked by GUS activity. (E) GUS expression in the vascular tissue of cotyledons.