TRIPTYCHON (TRY) is a small (106 aa) nuclear, cell-to-cell mobile R3-type MYB protein of Arabidopsis that lacks an R2 repeat and a recognizable transcriptional activation domain. TRY is a negative regulator of epidermal cell fate in the lateral-inhibition circuit of trichome patterning: its transcription is activated in incipient trichome cells by the GL1-GL3/EGL3-TTG1 (MBW) activator complex, and the TRY protein binds the bHLH proteins GL3/EGL3 and competes with the R2R3-MYB activator GL1, preventing formation of active MBW complexes. try mutants form trichome clusters and over-branched trichomes, and try cpc double mutants form large trichome clusters, showing that TRY and its paralog CAPRICE (CPC) suppress trichome fate in cells neighboring a developing trichome. TRY also acts redundantly with CPC and other R3 MYBs (ETC1-3, TCL1) to promote root hair cell fate in the root epidermis and represses its own promoter in a negative feedback loop.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000976 transcription cis-regulatory region binding | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: IBA cis-regulatory region binding from the deep MYB-domain node shared with R2R3 MYBs. Reason: TRY retains only the R3 repeat (no R2) and lacks an activation domain; its established in planta mechanism is binding GL3/EGL3 and competing with GL1, not sequence-specific promoter binding. A high-throughput yeast one-hybrid screen did, however, record TRY binding to a promoter fragment, so DNA-binding capacity is not excluded. Retained as non-core pending direct evidence for in vivo TRY DNA binding. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: PANTHER:PTN000067606 · PTN000067606 SUPPORTS TRANSFER Same deep MYB node that gives CPC this term (marked over-annotated there on the same R3-only structural argument). The node is seeded by R2R3 MYBs (AT5G40330, AT1G66230) and by TRY itself (AT5G53200, via its own yeast one-hybrid IPI), and that target-specific datum is what keeps the transfer defensible as non-core for TRY but not for CPC. Supporting Evidence: PMID:12356720 We show that the TRIPTYCHON gene that functions in lateral inhibition encodes a single-repeat MYB-related transcription factor that lacks a recognizable activation domain. PMID:25533953 The final network comprises 242 genes and 617 protein-DNA interactions |
| 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: TRY bound the promoter of AT4G36890 (IRX14) in a secondary cell wall gene regulatory network screen. Reason: Direct experimental but high-throughput heterologous evidence (bait fused to an activation domain in yeast); no follow-up indicates that TRY regulates secondary cell wall genes in planta. Kept as a non-core experimental observation. Supporting Evidence: PMID:25533953 The final network comprises 242 genes and 617 protein-DNA interactions |
| GO:0003700 DNA-binding transcription factor activity | ISS PMID:11118137 Arabidopsis transcription factors: genome-wide comparative a... | MODIFY | Summary: ISS DNA-binding transcription factor activity from the genome-wide TF survey (MYB-like domain). Reason: TRY lacks an activation domain and functions by binding the bHLH proteins GL3/EGL3 and preventing formation of the active GL1-GL3 complex. The informative activity is inhibition of a transcription regulator by direct binding, not sequence-specific DNA-binding TF activity. Proposed replacements: transcription regulator inhibitor activity Supporting Evidence: PMID:12356720 We show that the TRIPTYCHON gene that functions in lateral inhibition encodes a single-repeat MYB-related transcription factor that lacks a recognizable activation domain. PMID:14561633 TRY has the ability to prevent the GL1 GL3 interaction PMID:18766177 These inhibitors can compete with the R2R3 MYB factor for binding to GL3/EGL3 in yeast three-hybrid assays file:ARATH/TRY/TRY-deep-research-falcon.md a MYB-domain annotation alone does not establish direct DNA binding by TRY |
| GO:0005515 protein binding | IPI PMID:28650476 CrY2H-seq: a massively multiplexed assay for deep-coverage i... | REMOVE | Summary: CrY2H-seq high-throughput interaction with a homeodomain-like protein (At4g03250). Reason: Uninformative protein binding from a massively multiplexed Y2H screen with no functional follow-up. Removal does not assert that the interaction is false; TRY's informative partner binding (GL3/EGL3) is captured by transcription regulator inhibitor activity. Supporting Evidence: PMID:28650476 identify these interactions en masse |
| GO:0005515 protein binding | IPI PMID:28650476 CrY2H-seq: a massively multiplexed assay for deep-coverage i... | REMOVE | Summary: CrY2H-seq high-throughput interaction with bZIP43. Reason: Uninformative protein binding from a massively multiplexed Y2H screen with no functional follow-up. Removal does not assert that the interaction is false. Supporting Evidence: PMID:28650476 identify these interactions en masse |
| GO:0005634 nucleus | IBA GO_REF:0000033 | ACCEPT | Summary: IBA nucleus. Reason: Functional GFP-TRY localizes to trichome nuclei. Supporting Evidence: PMID:14561633 Analysis of plants expressing functional GFP-tagged versions of GL1, GL3 and TRY show that the proteins are localized in trichome nuclei. |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: IEA nucleus from UniProt subcellular location. Reason: Consistent with experimental localization. Supporting Evidence: PMID:14561633 Analysis of plants expressing functional GFP-tagged versions of GL1, GL3 and TRY show that the proteins are localized in trichome nuclei. |
| GO:0005634 nucleus | ISM GO_REF:0000122 | ACCEPT | Summary: ISM (AtSubP) nucleus. Reason: Consistent with experimental localization. Supporting Evidence: PMID:14561633 Analysis of plants expressing functional GFP-tagged versions of GL1, GL3 and TRY show that the proteins are localized in trichome nuclei. |
| GO:0006355 regulation of DNA-templated transcription | IBA GO_REF:0000033 | ACCEPT | Summary: IBA regulation of DNA-templated transcription. Reason: TRY regulates transcription indirectly by inhibiting the MBW activator complex; it represses its own promoter and MBW target activation. The general process term is correct. Supporting Evidence: PMID:21951724 we demonstrate that TRY and CPC can suppress the TRY expression without the transcriptional down regulation of the activators |
| GO:0006355 regulation of DNA-templated transcription | IEA GO_REF:0000117 | ACCEPT | Summary: IEA (ARBA) regulation of DNA-templated transcription. Reason: As for the IBA row. Supporting Evidence: PMID:21951724 we demonstrate that TRY and CPC can suppress the TRY expression without the transcriptional down regulation of the activators |
| GO:0006355 regulation of DNA-templated transcription | TAS PMID:11118137 Arabidopsis transcription factors: genome-wide comparative a... | ACCEPT | Summary: TAS regulation of DNA-templated transcription from the TF survey. Reason: As for the IBA row. Supporting Evidence: PMID:21951724 we demonstrate that TRY and CPC can suppress the TRY expression without the transcriptional down regulation of the activators |
| GO:0010026 trichome differentiation | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: IBA trichome differentiation. Reason: TRY does not perform trichome differentiation; it restricts which epidermal cells adopt trichome fate (lateral inhibition). The patterning term captures its role better; kept as non-core because try mutants do alter trichome differentiation (clusters, extra branches). Supporting Evidence: PMID:12356720 Both genes are expressed in trichomes and act together during lateral inhibition. |
| GO:0010026 trichome differentiation | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: IEA (ARBA) trichome differentiation. Reason: As for the IBA row. Supporting Evidence: PMID:12356720 Both genes are expressed in trichomes and act together during lateral inhibition. |
| GO:0010091 trichome branching | IMP PMID:10572032 Genetic control of trichome branch number in Arabidopsis: th... | KEEP AS NON CORE | Summary: IMP trichome branching: try is one of the branch-number mutants used in epistasis with FURCA loci. Reason: try trichomes are over-branched, consistent with TRY limiting trichome developmental programs; this is a downstream morphogenetic consequence rather than TRY's core patterning role. Supporting Evidence: PMID:10572032 Based on the analysis of both epistatic and additive genetic interactions between the FURCA genes and other genes that control trichome branch number |
| GO:0010154 fruit development | IMP PMID:3793867 Cytotoxic and enterotoxic activities of Campylobacter jejuni... | MARK AS OVER ANNOTATED | Summary: GOA cites PMID:3793867 (an unrelated Campylobacter plasmid paper); the intended source is very probably PMID:33955486 (Arteaga et al. 2021), which links cis-regulatory TRY alleles to natural trichome formation on fruits and pedicels. That is fruit-surface trichome patterning, not a role in fruit growth or maturation. Reason: The identification of PMID:33955486 as the intended paper is a strong inference, not TAIR-confirmed. TAIR made exactly three GO:0010154 annotations with PMID:3793867, to TCL1, GL1 and TRY, all on 20210127, and Arteaga et al. 2021 functionally characterized exactly these three MYB loci in fruit trichome patterning. Reduced TRY expression in reproductive organs permits ectopic epidermal trichome development on the fruit (carpel/silique) surface and pedicel, a phenotype of the MBW/R3-MYB trichome patterning network. It does not show a TRY role in gynoecium or silique growth, morphogenesis or maturation. The fruit-development term is therefore a low-information, over-broad reading of a trichome-patterning phenotype, and the underlying biology is already captured by the TRY trichome patterning terms. The original GOA reference id is retained. Supporting Evidence: PMID:33955486 Functional characterization of these three loci revealed cis-regulatory mutations in TRICHOMELESS1 and TRIPTYCHON, as well as a structural mutation in GLABRA1. PMID:33955486 Here we examined natural populations of Arabidopsis (Arabidopsis thaliana) that develop trichomes in fruits and pedicels, phenotypes previously not reported in the Arabidopsis genus. PMID:33955486 Thus, Don-0 allele at SNP-701, and/or other Iberian relict polymorphisms in LD, likely reduce TRY expression in the reproductive organs, leading to trichome development in fruits. PMID:18644155 single-repeat R3 MYBs normally suppress trichome formation on siliques and cotyledons |
| GO:0048765 root hair cell differentiation | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: IBA root hair cell differentiation (seeded by ETC2). Reason: TRY acts redundantly with CPC in root epidermal patterning, promoting hair cell fate; a real but secondary role outside the leaf trichome module. Supporting Evidence: PMID:12356720 We further show that TRIPTYCHON and CAPRICE act redundantly in the position-dependent cell fate determination in the root epidermis. |
| GO:1900032 regulation of trichome patterning | IEA GO_REF:0000117 | ACCEPT | Summary: IEA (ARBA) regulation of trichome patterning. Reason: TRY is a central inhibitor in trichome spacing. Supporting Evidence: PMID:12356720 Both genes are expressed in trichomes and act together during lateral inhibition. |
| GO:1900032 regulation of trichome patterning | IMP PMID:21951724 Role of TRIPTYCHON in trichome patterning in Arabidopsis. | ACCEPT | Summary: IMP: TRY promoter/CDS swap and feedback analyses establish TRY's specific role in trichome patterning. Reason: Direct experimental support for TRY in trichome patterning (cluster suppression and density). Supporting Evidence: PMID:21951724 Among the inhibitors TRIPTYCHON (TRY) seems to fulfill a special function. Its corresponding mutants produce trichome clusters whereas all other inhibitors are involved in trichome density regulation. |
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Download this section (compressed HTML)Q: Does TRY inhibit the MBW complex only by sequestering GL3/EGL3 away from GL1, or do TRY-GL3-TTG1 complexes also occupy target promoters as inactive complexes?
Q: What TRY-specific protein properties (absent from CPC) explain why only try mutants form trichome clusters?
Experiment: Quantify TRY-GFP mobility and nuclear trapping in young leaf epidermis by photoconversion in wild type versus gl3 egl3 backgrounds.
Hypothesis: TRY accumulation in cells neighbouring a trichome depends on GL3/EGL3-mediated nuclear retention.
Type: Live imaging / photoconvertible fusion
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