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Table 1 Summary of the experimental evidence

From: Single-cell and coupled GRN models of cell patterning in the Arabidopsis thaliana root stem cell niche

SHR →SCR The expression of SCR is reduced in shr mutants.
ChIP-QRTPCR experiments show that SHR directly binds in vivo to the regulatory sequences of SCR and positively regulates its transcription.
[9, 16]
SCR →SCR In the scr mutant background promoter activity of SCR is absent in the QC and CEI.
A ChIP-PCR assay confirmed that SCR directly binds to its own promoter and directs its own expression.
[10, 14]
JKD →SCR SCR mRNA expression as probed with a reporter lines is lost in the QC and CEI cells in jkd mutants from the early heart stage onward. [17]
MGP--|SCR The double mutant jkd mgp rescues the expression of SCR in the QC and CEI, which is lost in the jkd single mutant. [17]
SHR →MGP The expression of MGP is severely reduced in the shr background.
Experimental data using various approaches have suggested that MGP is a direct target of SHR. This result was later confirmed by ChIP-PCR.
[14, 16, 17]
SCR →MGP SCR directly binds to the MGP promoter, and MGP expression is reduced in the scr mutant background. [14, 17]
SHR →JKD The post-embryonic expression of JKD is reduced in shr mutant roots. [17]
SCR →JKD The post-embryonic expression of JKD is reduced in scr mutant roots. [17]
SCR →WOX5 WOX5 is not expressed in scr mutants. [24]
SHR →WOX5 WOX5 expression is reduced in shr mutants. [24]
ARF(MP) →WOX5 WOX5 expression is rarely detected in mp or bdl mutants. [24]
ARF→PLT PLT1 mRNA region of expression is reduced in multiple mutants of PIN genes, and it is overexpressed under ectopic auxin addition. PLT1 & 2 mRNAs are absent in the majority of mp embryos and even more so in mp nph4 double mutant embryos. [11, 12]
Aux/IAA--|ARF Overexpression of Aux/IAA genes represses the expression of DR5 both in the presence and absence of auxin.
Domains III & IV of Aux/IAA genes interact with domains III & IV of ARF stabilizing the dimerization that represses ARF transcriptional activity.
[22, 23]
Auxin--| Aux/IAA Auxin application destabilizes Aux/IAA proteins.
Aux/IAA proteins are targets of ubiquitin-mediated auxin-dependent degradation.
[reviewed in [18]]
CLE40 --| WOX5 Wild type root treated with CLE40p show a reduction of WOX5 expression, whereas in cle40 loss of function plants WOX5 is overexpressed. [25]
  1. Experimental evidence used to generate the four single cell GRNs. These previously reported results were the basis for the interactions postulated in the SCN GRN models graphs of figure 1.