RHT1 is a wheat DELLA protein that restrains gibberellin-responsive growth through nuclear interactions with transcriptional regulators. Its C-terminal GRAS region interacts with transcription factors including IDD5 and PLATZ1, linking gibberellin signaling to gene expression and cell elongation. Gibberellin promotes recognition of the N-terminal regulatory region by GID1 and subsequent ubiquitin-dependent degradation, releasing growth restraint. Green Revolution Rht-B1b and Rht-D1b alleles produce N-terminally truncated proteins by translational reinitiation; these proteins resist gibberellin-induced degradation and confer reduced stem elongation.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: Nuclear localization is consistent with curated DELLA localization and directly observed RHT-D1–IDD5 interaction. Reason: UniProt records nucleus by similarity. In the primary 2026 wheat study, BiFC with an N-terminally truncated RHT-D1 construct and IDD5, together with DAPI, localizes the interaction to the nucleus. This is direct target-family evidence with the construct limitation stated; the nuclear location of TaGID2 alone is not treated as a localization assay of RHT1. Supporting Evidence: file:WHEAT/RHT1/RHT1-uniprot.txt SUBCELLULAR LOCATION: Nucleus PMID:41615756 the interaction occurs in the nucleus |
| GO:0009740 gibberellic acid mediated signaling pathway | IEA GO_REF:0000043 | MODIFY | Summary: The retired signaling annotation captures a genuine core pathway role; the negative-regulation term adds precision. Reason: Wheat RHT proteins restrain gibberellin-responsive growth, and their hormone-triggered degradation releases that restraint. Wild-type protein degradation and stabilized dwarfing alleles are directly demonstrated in PMID:33422695. RHT1 therefore does regulatory work in the signaling pathway, beyond merely being a degradation substrate. Recommend GO:0009938 for that inhibitory role. Retirement of a keyword mapping route does not itself establish a biological rejection or a curator error. Proposed replacements: negative regulation of gibberellic acid mediated signaling pathway Supporting Evidence: PMID:33422695 their degradation in response to GAs. |
| GO:0140297 DNA-binding transcription factor binding | IPI PMID:41615756 INDETERMINATE DOMAIN-DELLA protein interactions orchestrate ... | NEW | Summary: RHT-D1 physically interacts with IDD5, a DNA-binding transcription factor. Reason: Primary yeast two-hybrid and nuclear BiFC experiments demonstrate interaction of the RHT-D1 GRAS-containing truncation with IDD5. Independent wheat PLATZ1 interaction evidence is reported in PMID:37126674. This specific binding function captures the measured molecular activity without assuming that every partner interaction represses transcription at a genomic locus. The 2026 paper explicitly leaves IDD5 sequestration versus coactivation unresolved. The N-terminal truncation used in the interaction assays is described in the evidence; this is not a separate natural isoform annotation. Supporting Evidence: PMID:41615756 full-length IDD5-A1 interacted strongly with ∆RHT-D1 |
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Download this section (compressed HTML)Q: Does RHT-D1 inhibit IDD5 DNA binding, or recruit coactivators to IDD5 target loci? PMID:41615756 explicitly leaves both mechanisms open; resolving this requires target-promoter and transcriptional assays.
Q: Which RHT1–PLATZ1 interactions alter transcription and growth, and how do their effects differ from the RHT1–IDD5 interaction?
Experiment: Combine RHT-D1/IDD5 interaction mutants with promoter occupancy and transcriptional reporters at independently mapped IDD5 targets, comparing full-length and N-terminally truncated RHT-D1.
Hypothesis: The same DELLA growth phenotype may arise through TF sequestration or coactivation of growth-inhibitory genes.
Type: interaction mutagenesis and transcriptional regulation
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