WOX5 (WUSCHEL-RELATED HOMEOBOX 5) is a plant-specific homeodomain transcription factor of the WUS-related WOX family that functions as the master regulator of the root stem cell niche organizer (quiescent center, QC) in Arabidopsis thaliana. WOX5 is expressed specifically in the QC, where it acts largely as a transcriptional repressor. The WOX5 protein moves from the QC into the adjacent columella (distal) stem cells, where it directly represses transcription of the differentiation-promoting transcription factor gene CDF4 by recruiting TOPLESS/TOPLESS-RELATED (TPL/TPR) corepressors and the histone deacetylase HDA19, thereby establishing a CDF4 gradient that keeps the cells adjacent to the QC undifferentiated while permitting their daughters to differentiate. Through this non-cell-autonomous repressive signal WOX5 maintains the columella stem cells and the QC, preserving root apical meristem identity. WOX5 expression is positioned within the root auxin gradient and is responsive to auxin; it is confined to the QC by the PHD-finger protein ROW1 (which represses ectopic WOX5 in the proximal meristem) and acts within the broader SHORTROOT/SCARECROW and PLETHORA regulatory networks that pattern the root tip. The protein contains a single WUS-type homeodomain (residues ~20-84) that mediates sequence-specific DNA binding, and it acts within the nucleus.
Definition: The process in which the columella (distal) stem cells beneath the root quiescent center are kept in an undifferentiated, self-renewing state, for example by an organizer-derived repressive signal that prevents premature differentiation.
Justification: WOX5 specifically maintains the columella/distal stem cells (those immediately contacting the QC), a process more specific than the generic positive regulation of stem cell population maintenance and not fully captured by existing terms.
Parent term: positive regulation of stem cell population maintenance
Supporting Evidence:
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0006355 regulation of DNA-templated transcription | IBA GO_REF:0000033 | ACCEPT | Summary: WOX5 is a WUS-type homeodomain transcription factor and acts on transcription; experimental evidence shows it directly represses the target gene CDF4 in columella stem cells. The IBA phylogenetic annotation to the generic regulation of DNA-templated transcription is correct but relatively unspecific. WOX5 acts predominantly as a repressor, so a more specific child term (negative regulation of transcription) is preferable where supported; this generic parent is retained as an accurate but non-core summary statement. Reason: Accurate, conservative IBA annotation consistent with WOX5 being a DNA-binding transcription factor that regulates transcription of target genes. A more specific repressor term is added separately as a NEW annotation. Supporting Evidence: PMID:26028217 the WOX5 protein moves from the root niche organizer, the quiescent center, into the columella stem cells, where it directly represses the transcription factor gene CDF4. file:ARATH/WOX5/WOX5-deep-research-falcon.md it functions as both transcriptional repressor and activator and alters histone modifications and chromatin accessibility in QC cells. |
| GO:0003677 DNA binding | IEA GO_REF:0000002 | MODIFY | Summary: WOX5 contains a WUS-type homeobox/homeodomain (UniProt DNA_BIND 20..84) and binds DNA. DNA binding is correct but generic; for a sequence-specific homeodomain transcription factor the more informative child term sequence-specific DNA binding (already annotated from PMID:26028217) is preferable. This InterPro-derived IEA is a true but shallow parent. Reason: The term is correct but too general for a sequence-specific homeodomain transcription factor. Replace with sequence-specific DNA binding, which is independently supported experimentally and by the WUS-type homeobox domain. Proposed replacements: sequence-specific DNA binding Supporting Evidence: file:ARATH/WOX5/WOX5-uniprot.txt DNA_BIND 20..84 /note="Homeobox; WUS-type" file:ARATH/WOX5/WOX5-deep-research-falcon.md WOX5 binds a cis-regulatory fragment ~200–121 bp upstream containing TAAT motifs. |
| GO:0003700 DNA-binding transcription factor activity | IEA GO_REF:0000002 | ACCEPT | Summary: WOX5 is a homeodomain transcription factor that binds DNA in a sequence-specific manner and regulates target gene transcription (e.g., direct repression of CDF4). The InterPro IEA to DNA-binding transcription factor activity is well supported. Since WOX5 functions predominantly as a repressor, the more specific child term DNA-binding transcription repressor activity (GO:0001217) better captures its mode of action and is proposed as a NEW annotation; the parent is accepted as correct. Reason: Correct molecular function for a WUS-type homeodomain transcription factor with demonstrated sequence-specific DNA binding and direct target gene regulation. Supporting Evidence: PMID:26028217 where it directly represses the transcription factor gene CDF4. file:ARATH/WOX5/WOX5-uniprot.txt DNA_BIND 20..84 /note="Homeobox; WUS-type" file:ARATH/WOX5/WOX5-deep-research-falcon.md Arabidopsis WOX5 (At3g11260; UniProt Q8H1D2) is a WUSCHEL-related homeobox transcription factor of the WUS clade, specifically expressed in the quiescent center (QC). |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: As a homeodomain transcription factor that represses target genes via chromatin-mediated mechanisms, WOX5 acts in the nucleus. UniProt curates nuclear localization from its WUS-type homeodomain. This is consistent with its DNA-binding and transcriptional repressor function. Reason: Nuclear localization is expected and curated for this DNA-binding transcription factor and is consistent with chromatin-level repression of CDF4. Supporting Evidence: file:ARATH/WOX5/WOX5-uniprot.txt SUBCELLULAR LOCATION: Nucleus file:ARATH/WOX5/WOX5-deep-research-falcon.md WOX5 is consistently characterized and experimentally used as a transcription factor with direct DNA binding and promoter occupancy (e.g., CDF4 promoter binding and ChIP enrichment), implying |
| GO:0099402 plant organ development | IEA GO_REF:0000120 | MARK AS OVER ANNOTATED | Summary: WOX5 functions in root development (root apical meristem / stem cell niche), so it does participate in plant organ development. However, this term is very broad and non-specific; WOX5's role is well captured by more specific terms such as maintenance of root meristem identity (GO:0010078) and positive regulation of stem cell population maintenance (GO:1902459), which are already annotated. Reason: Generic IEA keyword/ARBA mapping. The specific WOX5 developmental role is already captured by more informative terms; the broad parent over-annotates the gene. Supporting Evidence: PMID:25631790 WOX5 may be a target of ROW1 |
| GO:0005515 protein binding | IPI PMID:29352064 GIF Transcriptional Coregulators Control Root Meristem Homeo... | REMOVE | Summary: This IPI annotation derives from a study of GRF-INTERACTING FACTORs (GIFs) in root meristem homeostasis. The generic protein binding term is uninformative about WOX5 molecular function. The paper characterizes GIF coregulators and QC homeostasis but does not establish a specific, mechanistically informative WOX5 binding partner that would warrant a more precise MF term here. Reason: Uninformative generic protein binding term that conveys no specific molecular function. Per curation guidelines this term should be avoided in favor of informative MF terms. Supporting Evidence: PMID:29352064 GIFs cannot bind to DNA per se, but they can function as coactivators of the GRFs |
| GO:0005634 nucleus | ISM GO_REF:0000122 | ACCEPT | Summary: Sequence-based (AtSubP) prediction of nuclear localization, consistent with the curated UniProt nuclear location and with WOX5's function as a DNA-binding transcriptional repressor. Duplicate of the nucleus annotation; accepted. Reason: Consistent with curated nuclear localization and with WOX5's transcription factor function. Duplicate CC annotations are acceptable. Supporting Evidence: file:ARATH/WOX5/WOX5-uniprot.txt SUBCELLULAR LOCATION: Nucleus |
| GO:0043565 sequence-specific DNA binding | IPI PMID:26028217 Organizer-Derived WOX5 Signal Maintains Root Columella Stem ... | ACCEPT | Summary: WOX5 is a WUS-type homeodomain transcription factor that binds the CDF4 regulatory region and directly represses CDF4 transcription. This sequence-specific DNA binding is the core biochemical activity underlying its repressor function in columella stem cells. Well supported. Reason: Core molecular function. Sequence-specific DNA binding by the WUS-type homeodomain underlies WOX5 direct repression of its target gene CDF4. Supporting Evidence: PMID:26028217 the WOX5 protein moves from the root niche organizer, the quiescent center, into the columella stem cells, where it directly represses the transcription factor gene CDF4. file:ARATH/WOX5/WOX5-uniprot.txt DNA_BIND 20..84 /note="Homeobox; WUS-type" file:ARATH/WOX5/WOX5-deep-research-falcon.md experimentally, it binds cis-regulatory DNA elements and controls transcription of developmental regulators. |
| GO:0005515 protein binding | IPI PMID:26028217 Organizer-Derived WOX5 Signal Maintains Root Columella Stem ... | REMOVE | Summary: PMID:26028217 shows WOX5 represses CDF4 by recruiting TPL/TPR corepressors and the histone deacetylase HDA19. The interacting partners identified (AGI loci corresponding to TPL/TPR-class corepressors and HDA19) are transcriptional corepressors. The generic protein binding term is uninformative; the mechanistically relevant interaction is binding to transcription corepressors, captured by GO:0001222 (transcription corepressor binding), proposed as a NEW annotation. Reason: Uninformative generic protein binding term. The specific and informative interaction (recruitment of TPL/TPR corepressors and HDA19) is captured by a dedicated NEW transcription corepressor binding annotation. Supporting Evidence: PMID:26028217 WOX5 represses CDF4 transcription by recruiting TPL/TPR co-repressors and the histone deacetylase HDA19, which consequently induces histone deacetylation at the CDF4 regulatory region. |
| GO:1902459 positive regulation of stem cell population maintenance | IMP PMID:26028217 Organizer-Derived WOX5 Signal Maintains Root Columella Stem ... | ACCEPT | Summary: Loss of WOX5 (wox5 mutant) causes differentiation of the columella stem cells subtending the QC, while QC-derived WOX5 signal maintains the columella (distal) stem cells in an undifferentiated state. WOX5 therefore positively regulates stem cell population maintenance. Strong genetic and mechanistic support. Reason: Core biological process. WOX5 maintains columella/distal stem cells; its loss leads to premature stem cell differentiation. Supporting Evidence: PMID:26028217 Organizer-Derived WOX5 Signal Maintains Root Columella Stem Cells through Chromatin-Mediated Repression of CDF4 Expression. PMID:25631790 QC expression of WOX5 is essential for maintenance of DSC activity. file:ARATH/WOX5/WOX5-deep-research-falcon.md it promotes QC mitotic quiescence and maintains the underlying columella stem cells (CSCs) in an undifferentiated state. |
| GO:0010078 maintenance of root meristem identity | IMP PMID:25631790 ROW1 maintains quiescent centre identity by confining WOX5 e... | ACCEPT | Summary: WOX5 is required for QC identity and root apical meristem maintenance; its mis-expression or loss disrupts QC identity and columella differentiation. UniProt FUNCTION states WOX5 is involved in specification and maintenance of QC stem cells in the root apical meristem. Core process. Reason: Core biological process strongly supported by genetic evidence (wox5 and row1/WOX5 mis-expression phenotypes) and UniProt curation. Supporting Evidence: PMID:25631790 QC expression of WOX5 is essential for maintenance of DSC activity. file:ARATH/WOX5/WOX5-uniprot.txt Transcription factor, which may be involved in the specification and maintenance of the stem cells (QC cells) in the root apical meristem (RAM). file:ARATH/WOX5/WOX5-deep-research-falcon.md WOX5 is a central organizer factor in the root stem cell niche |
| GO:0009733 response to auxin | IEP PMID:16262712 A turanose-insensitive mutant suggests a role for WOX5 in au... | KEEP AS NON CORE | Summary: WOX5 expression is auxin-inducible (and turanose-inducible), and WOX5 is positioned within the root auxin gradient; a turanose-insensitive WOX5 loss-of-function mutant shows altered auxin homeostasis. This IEP annotation reflects WOX5 expression responding to auxin and its involvement in auxin-related root patterning. This is a peripheral/upstream regulatory relationship rather than WOX5's core molecular function. Reason: Supported by expression evidence (auxin-inducible) and a loss-of-function phenotype affecting auxin homeostasis, but this is an upstream/contextual relationship, not the core stem cell maintenance function of WOX5. Supporting Evidence: PMID:16262712 We found that WOX5 is both turanose- and auxin-inducible. PMID:16262712 we propose a role for WOX5 in the root apical meristem as a negative trigger of IAA homeostatic mechanisms allowing the maintenance of a restricted area of auxin maximum file:ARATH/WOX5/WOX5-deep-research-falcon.md WOX5 promotes local auxin biosynthesis in the QC and participates in a regulatory relationship with auxin response maxima that support organizer function. |
| GO:0003700 DNA-binding transcription factor activity | ISS PMID:11118137 Arabidopsis transcription factors: genome-wide comparative a... | ACCEPT | Summary: WOX5 was classified as a transcription factor in the genome-wide Arabidopsis transcription factor analysis (homeobox/homeodomain class). This ISS annotation to DNA-binding transcription factor activity is correct and consistent with the experimentally demonstrated sequence-specific DNA binding and direct target repression. Duplicate of the InterPro IEA; accepted. Reason: Correct molecular function supported by membership in the homeodomain transcription factor class and by experimental DNA binding. Duplicate MF annotations are acceptable. Supporting Evidence: PMID:11118137 Arabidopsis dedicates over 5% of its genome to code for more than 1500 transcription factors PMID:26028217 where it directly represses the transcription factor gene CDF4. |
| GO:0001217 DNA-binding transcription repressor activity | IDA PMID:26028217 Organizer-Derived WOX5 Signal Maintains Root Columella Stem ... | NEW | Summary: NEW annotation. WOX5 binds the CDF4 regulatory region in a sequence-specific manner and directly represses CDF4 transcription by recruiting TPL/TPR corepressors and HDA19, inducing histone deacetylation. This establishes WOX5 as a DNA-binding transcriptional repressor, a more informative molecular function than the generic DNA-binding transcription factor activity. (The RNA polymerase II-specific child GO:0001227 is avoided as plant repressor annotations conventionally use the generic term.) Reason: Captures the specific, experimentally demonstrated repressor mode of action of WOX5 at its direct target CDF4, replacing reliance on the generic DNA-binding transcription factor activity term. Supporting Evidence: PMID:26028217 where it directly represses the transcription factor gene CDF4. This creates a gradient of CDF4 transcription, which promotes differentiation opposite to the WOX5 gradient PMID:26028217 WOX5 represses CDF4 transcription by recruiting TPL/TPR co-repressors and the histone deacetylase HDA19 file:ARATH/WOX5/WOX5-deep-research-falcon.md 17 of them downregulated, highlighting strong repressor activity in that context. |
| GO:0001222 transcription corepressor binding | IPI PMID:26028217 Organizer-Derived WOX5 Signal Maintains Root Columella Stem ... | NEW | Summary: NEW annotation. WOX5 recruits the TOPLESS/TOPLESS-RELATED (TPL/TPR) corepressors and the histone deacetylase HDA19 to repress CDF4. Binding these transcriptional corepressors is the informative molecular function underlying the WOX5 protein-binding interactions reported in PMID:26028217, replacing the generic protein binding annotations. Reason: Provides an informative molecular function for the WOX5 protein-protein interactions (TPL/TPR and HDA19 recruitment) that the generic GO:0005515 annotations failed to convey. Supporting Evidence: PMID:26028217 WOX5 represses CDF4 transcription by recruiting TPL/TPR co-repressors and the histone deacetylase HDA19 file:ARATH/WOX5/WOX5-deep-research-falcon.md WOX5 interacts with TPL/TPR; via TPL/TPRs it recruits HDA19, reducing histone H3 acetylation at the CDF4 regulatory region. |
| GO:0045892 negative regulation of DNA-templated transcription | IDA PMID:26028217 Organizer-Derived WOX5 Signal Maintains Root Columella Stem ... | NEW | Summary: NEW annotation. WOX5 directly represses transcription of CDF4 via recruitment of TPL/TPR corepressors and HDA19-mediated histone deacetylation, a clear negative regulation of transcription. This biological process complements the generic regulation-of-transcription IBA term with the experimentally established direction of regulation (repression). Reason: WOX5 acts predominantly as a transcriptional repressor at its direct target CDF4; the specific negative-regulation term is supported by direct experimental evidence. Supporting Evidence: PMID:26028217 WOX5 represses CDF4 transcription by recruiting TPL/TPR co-repressors and the histone deacetylase HDA19, which consequently induces histone deacetylation at the CDF4 regulatory region. file:ARATH/WOX5/WOX5-deep-research-falcon.md A central mechanistic insight is that WOX5 directly represses **CDF4** (a differentiation-promoting DOF transcription factor) in the QC/CSC region. |
| GO:0045596 negative regulation of cell differentiation | IMP PMID:26028217 Organizer-Derived WOX5 Signal Maintains Root Columella Stem ... | NEW | Summary: NEW annotation. The QC-derived WOX5 signal keeps columella (distal) stem cells undifferentiated by repressing the differentiation-promoting factor CDF4; loss of WOX5 leads to premature differentiation (e.g., ectopic starch granule accumulation) of the distal stem cells. WOX5 thus negatively regulates cell differentiation in the root distal stem cell niche. Reason: Strong genetic and mechanistic evidence that WOX5 suppresses differentiation of columella stem cells; this is central to its biological role and is not captured by the existing broad organ-development term. Supporting Evidence: PMID:26028217 allowing stem cell daughter cells to exit the stem cell state. PMID:25631790 suggesting that these cells underwent premature differentiation. file:ARATH/WOX5/WOX5-deep-research-falcon.md Loss of WOX5 causes CSC differentiation beneath the QC and ectopic QC divisions |
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Download this section (compressed HTML)Q: Beyond CDF4, what is the genome-wide set of direct WOX5 DNA-binding targets in the QC and columella stem cells, and which are activated versus repressed?
Q: What is the precise DNA sequence motif bound by the WOX5 WUS-type homeodomain, and does WOX5 bind DNA as a monomer or in complexes with partners such as PLETHORA?
Q: How is WOX5 cell-to-cell movement from the QC into columella stem cells regulated, and is movement required for CDF4 repression in vivo?
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