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. Author manuscript; available in PMC: 2017 Dec 5.
Published in final edited form as: Dev Cell. 2016 Oct 27;39(5):585–596. doi: 10.1016/j.devcel.2016.09.031

Figure 6. Repressor Motifs within the SHORTROOT Promoter Function outside the Vasculature.

Figure 6

(A) Two repressors, ZML1 and DDF1, are predicted to bind within the first 500 bp of the SHR gene. The highest-scoring motifs (red arrowheads) for each were inserted into the RCH1 promoter.

(B) pRCH1::GAL4-UAS::ER-GFP is expressed broadly across the root tip, excluding the QC and root cap.

(C) Synthetic promoters were generated with the ZML1 and DDF1 motifs from the SHR promoter. T2 plants with three or six copies of the ZML1 motif show stochastic reduction of GFP expression in external cell files (white arrowheads), with no apparent differences between three or six copies of the motif (top panels). Three copies of the DDF1 motif also show reduced GFP expression (white arrowheads), but six copies drive ectopic expression in the QC (white arrows, middle panels). To assay the synergy of binding sites, we inserted two repeats of each motif in tandem once or twice in the RCH1 promoter (bottom panels). In these lines, we observe an overall reduction of GFP expression, and stochastic loss of GFP within a cell file (white arrowheads). These results suggest that the ZML1 and DDF1 motifs within the SHR promoter function to repress gene expression outside of the central vasculature.