BRANCHED1 (BRC1; TCP18, TEOSINTE BRANCHED1-LIKE1) is a class II (CYC/TB1-type) TCP-domain transcription factor expressed mainly in axillary buds, where it promotes bud dormancy and suppresses bud outgrowth; it is the Arabidopsis counterpart of maize TEOSINTE BRANCHED1. BRC1 is nuclear, binds GC-rich TCP-type sites (consensus GGgcCCmc) and directly activates the class I HD-ZIP genes HB21, HB40 and HB53, which in turn promote NCED3 expression and abscisic acid accumulation inside the bud; it also down-regulates cell-cycle and ribosome gene networks. BRC1 transcription integrates branching signals: it is raised by strigolactone (via SL-triggered degradation of the SMXL6/7/8 co-repressors), shade (low R:FR) and apical dominance, and lowered by decapitation and sugar/cytokinin signals. brc1 mutants are highly branched and show reduced responses to strigolactone, shade and auxin-mediated apical dominance, although BRC1 expression sets bud activation potential rather than being strictly necessary or sufficient for bud arrest.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000976 transcription cis-regulatory region binding | IPI PMID:25533953 An Arabidopsis gene regulatory network for secondary cell wa... | KEEP AS NON CORE | Summary: Yeast one-hybrid binding of BRC1 to promoters of secondary cell wall regulators. Reason: Large-scale Y1H screen; DNA binding by BRC1 is well supported, but these particular target promoters have no in planta validation and fall outside BRC1's established bud role. |
| GO:0003700 DNA-binding transcription factor activity | IBA GO_REF:0000033 | ACCEPT | Summary: BRC1 is a TCP-domain DNA-binding transcription factor. Reason: BRC1 binds TCP-type DNA motifs and directly activates HB21/HB40/HB53; this is its core molecular activity. Supporting Evidence: PMID:28028241 the TEOSINTE BRANCHED1, CYCLOIDEA, PCF (TCP) transcription factor BRANCHED1 (BRC1) binds to and positively regulates the transcription of three related Homeodomain leucine zipper protein (HD-ZIP)-encoding genes |
| GO:0003700 DNA-binding transcription factor activity | IEA GO_REF:0000002 | ACCEPT | Summary: BRC1 is a TCP-domain DNA-binding transcription factor. Reason: BRC1 binds TCP-type DNA motifs and directly activates HB21/HB40/HB53; this is its core molecular activity. Supporting Evidence: PMID:28028241 the TEOSINTE BRANCHED1, CYCLOIDEA, PCF (TCP) transcription factor BRANCHED1 (BRC1) binds to and positively regulates the transcription of three related Homeodomain leucine zipper protein (HD-ZIP)-encoding genes |
| GO:0003700 DNA-binding transcription factor activity | ISS PMID:11118137 Arabidopsis transcription factors: genome-wide comparative a... | ACCEPT | Summary: BRC1 is a TCP-domain DNA-binding transcription factor. Reason: BRC1 binds TCP-type DNA motifs and directly activates HB21/HB40/HB53; this is its core molecular activity. Supporting Evidence: PMID:28028241 the TEOSINTE BRANCHED1, CYCLOIDEA, PCF (TCP) transcription factor BRANCHED1 (BRC1) binds to and positively regulates the transcription of three related Homeodomain leucine zipper protein (HD-ZIP)-encoding genes |
| GO:0005515 protein binding | IPI PMID:28650476 CrY2H-seq: a massively multiplexed assay for deep-coverage i... | REMOVE | Summary: High-throughput Y2H interaction from a systematic interactome screen. Reason: Systematic-screen interaction without functional follow-up for BRC1; protein binding is uninformative. Removal does not imply the interaction is false. |
| GO:0005515 protein binding | IPI PMID:28650476 CrY2H-seq: a massively multiplexed assay for deep-coverage i... | REMOVE | Summary: High-throughput Y2H interaction from a systematic interactome screen. Reason: Systematic-screen interaction without functional follow-up for BRC1; protein binding is uninformative. Removal does not imply the interaction is false. |
| GO:0005515 protein binding | IPI PMID:28650476 CrY2H-seq: a massively multiplexed assay for deep-coverage i... | REMOVE | Summary: High-throughput Y2H interaction from a systematic interactome screen. Reason: Systematic-screen interaction without functional follow-up for BRC1; protein binding is uninformative. Removal does not imply the interaction is false. |
| GO:0005515 protein binding | IPI PMID:28650476 CrY2H-seq: a massively multiplexed assay for deep-coverage i... | REMOVE | Summary: High-throughput Y2H interaction from a systematic interactome screen. Reason: Systematic-screen interaction without functional follow-up for BRC1; protein binding is uninformative. Removal does not imply the interaction is false. |
| GO:0005515 protein binding | IPI PMID:28650476 CrY2H-seq: a massively multiplexed assay for deep-coverage i... | REMOVE | Summary: High-throughput Y2H interaction from a systematic interactome screen. Reason: Systematic-screen interaction without functional follow-up for BRC1; protein binding is uninformative. Removal does not imply the interaction is false. |
| GO:0005515 protein binding | IPI PMID:32612234 Extensive signal integration by the phytohormone protein net... | REMOVE | Summary: High-throughput Y2H interaction from a systematic interactome screen. Reason: Systematic-screen interaction without functional follow-up for BRC1; protein binding is uninformative. Removal does not imply the interaction is false. |
| GO:0005634 nucleus | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference of nuclear activity for TCP factors. Reason: Consistent with direct observation of nuclear GFP:BRC1. |
| GO:0005634 nucleus | IDA PMID:17307924 Arabidopsis BRANCHED1 acts as an integrator of branching sig... | ACCEPT | Summary: GFP:BRC1 is nuclear in all tissues examined. Reason: Direct localisation evidence for a transcription factor. Supporting Evidence: PMID:17307924 GFP:BRC1 and GFP:BRC2 were targeted to the nuclei in all tissues analyzed |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping to nucleus. Reason: Consistent with experimental evidence. |
| GO:0005634 nucleus | ISM GO_REF:0000122 | ACCEPT | Summary: AtSubP prediction of nucleus. Reason: Consistent with experimental evidence. |
| GO:0006355 regulation of DNA-templated transcription | TAS PMID:11118137 Arabidopsis transcription factors: genome-wide comparative a... | KEEP AS NON CORE | Summary: Genome-wide classification of BRC1 among TCP transcription factors. Reason: Correct but generic; the specific processes (bud dormancy, regulation of secondary shoot formation) are captured in core_functions. |
| GO:0010075 regulation of meristem growth | IMP PMID:30865619 Connective auxin transport contributes to strigolactone-medi... | KEEP AS NON CORE | Summary: BRC1 affects axillary meristem (bud) growth in branching assays. Reason: Reasonable description of bud-growth control but less specific than regulation of secondary shoot formation. |
| GO:0010223 secondary shoot formation | IMP PMID:23524661 BRANCHED1 promotes axillary bud dormancy in response to shad... | MODIFY | Summary: brc1 mutants fail to suppress branching in response to simulated shade. Reason: BRC1 does not form secondary shoots; it promotes the dormancy of axillary buds in response to shade. Bud dormancy process describes the role more precisely. Proposed replacements: bud dormancy process Supporting Evidence: PMID:23524661 The Arabidopsis thaliana gene BRANCHED1 (BRC1), expressed in axillary buds, is required for branch suppression in response to shade. |
| GO:0043565 sequence-specific DNA binding | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference of sequence-specific DNA binding for TCP factors. Reason: Protein-binding microarray assays define a BRC1 consensus binding motif. Supporting Evidence: PMID:28028241 The consensus binding motif obtained was GGgcCCmc |
| GO:0160109 plant gross anatomical part developmental process | IEA GO_REF:0000117 | MARK AS OVER ANNOTATED | Summary: ARBA prediction of plant gross anatomical part developmental process. Reason: Very general; BRC1's role is specifically in axillary bud dormancy and branching. |
| GO:1902347 response to strigolactone | IMP PMID:30865619 Connective auxin transport contributes to strigolactone-medi... | ACCEPT | Summary: brc1brc2 mutants show a reduced but significant response to strigolactone. Reason: BRC1 is a transcriptional output of SL signalling (induced when SMXL6/7/8 are degraded) and is required for the full SL response, although SL also acts BRC1-independently via auxin transport. Supporting Evidence: PMID:30865619 We have previously shown that brc1brc2 mutants show a reduced but significant response to strigolactone PMID:26546446 the BRC1 gene was strongly repressed in max2-1 and max3-9 but was induced in smxl6/7/8 |
| GO:2000032 regulation of secondary shoot formation | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference (TB1/BRC clade) of regulation of secondary shoot formation. Reason: TB1-like genes repress branching across angiosperms; consistent with Arabidopsis experimental data. |
| GO:2000032 regulation of secondary shoot formation | IMP PMID:17307924 Arabidopsis BRANCHED1 acts as an integrator of branching sig... | ACCEPT | Summary: brc1 mutants are highly branched; BRC1 arrests axillary bud development downstream of the MAX pathway. Reason: Core biological role of BRC1, supported by loss-of-function and epistasis data. Supporting Evidence: PMID:17307924 BRC1 is expressed in developing buds, where it arrests bud development. PMID:17307924 indicating that MAX and BRC1 may act in the same pathway and that the MAX effect on branching could be attributable mostly to transcriptional control of BRC1 |
| GO:2000032 regulation of secondary shoot formation | IMP PMID:30865619 Connective auxin transport contributes to strigolactone-medi... | ACCEPT | Summary: brc1brc2 mutants are highly branched and show altered strigolactone responses. Reason: Supports the core role in branching control. Supporting Evidence: PMID:30865619 Mutants lacking BRC1, and to a lesser extent the closely related BRC2, show increased branching compared to wild type |
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Download this section (compressed HTML)Q: Which BRC1 direct targets besides HB21/HB40/HB53 mediate cell-cycle and ribosome gene repression in dormant buds, and does BRC1 repress them directly or by competing with class I TCPs?
Q: How is BRC1 protein activity (not only transcript level) regulated, e.g. by interaction with FT/TSF florigens or SMXL-associated factors, given that high BRC1 transcript can coexist with active buds?
Experiment: Bud-specific ChIP-seq of tagged BRC1 under SL treatment and shade, combined with RNA-seq of brc1 brc2 buds, to define direct BRC1 targets and their SL dependence.
Type: genomics (ChIP-seq/RNA-seq)
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