| Category | Item | Key details | Evidence / quantitative notes | Citation |
|---|---|---|---|---|
| Identifier / protein | RHT-1 (UniProt Q9ST59) | Wheat DELLA protein of the GRAS family; corresponds to Reduced height 1 proteins encoded by homeologous loci **Rht-A1, Rht-B1, Rht-D1** in *Triticum aestivum* | Canonical DELLA architecture verified for wheat RHT-1 proteins; Rht-B1/Rht-D1 are Green Revolution loci | (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000006) |
| Domain architecture | N-terminal DELLA regulatory region | Conserved motifs **DELLA**, **LExLE/LEQLE**, **TVHYNP/VHYNP**; required for GA receptor **GID1** recognition | Loss/disruption of these motifs prevents normal GA-triggered degradation | (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000005) |
| Domain architecture | C-terminal GRAS region | Conserved motifs **LHRI**, **VHIID**, **LHRII**, **PFYRE**, **SAW**; functional repression / partner interaction region | PFYRE and SAW motifs implicated in DELLA activity and partner interactions | (pqac-00000000, pqac-00000004, pqac-00000007) |
| Mechanism | GA–GID1–DELLA module | GA-bound GID1 binds DELLA N-terminus, enabling SCF E3 ligase recruitment, ubiquitination, and proteasomal DELLA degradation | RHT-1 acts as a **growth repressor** in GA signaling; degradation relieves repression | (pqac-00000000, pqac-00000005, pqac-00000014) |
| Key allele | **Rht-B1b** | Premature stop codon in N-terminal region; produces N-terminally truncated DELLA via translational reinitiation | Truncated protein lacks DELLA/TVHYNP-type motifs, fails normal GID1-mediated degradation, causing GA-insensitive semi-dwarfism; reduces coleoptile length; in a 245-line RIL population, the 4BS coleoptile QTL explained **~19.7–22.2%** variance (9.1–22.2% across environments); parent CL example: **~3.3 cm** (Rht-B1b/Rht-D1b) vs **~4.8 cm** wild type; literature cited in 2024 work notes **~24.6%** PH reduction in one panel and ~23% stem-length reduction in prior studies | (pqac-00000001, pqac-00000009, pqac-00000011, pqac-00000015) |
| Key allele | **Rht-D1b** | Green Revolution semi-dwarf allele producing N-terminally truncated DELLA | GA-insensitive because truncated DELLA cannot be properly recognized/degraded via GID1 pathway; 4DS coleoptile QTL explained **~11–13.2%** variance in the 2023 study; one 2024 panel reported **~30.4%** PH reduction; Nordic–Baltic GWAS detected a chr4D DELLA marker explaining up to **29.16%** PH variance | (pqac-00000001, pqac-00000009, pqac-00000015, pqac-00000017) |
| Key allele | **Rht-B1c** | 508-nt insertion causing a 30-aa insertion in the DELLA domain | Abolishes/strongly impairs GID1 interaction; stable accumulation across tissues; produces a **severe dwarf** phenotype stronger than Rht-B1b/D1b | (pqac-00000005, pqac-00000012, pqac-00000014) |
| Key allele | **Rht-A1h** | 2024 novel allele; **G131A missense** in the DELLA motif region | Co-segregated with major chr4A QTL; reduced GA sensitivity consistent with altered DELLA–GID1 interaction; explained up to **53%** of PH variation and reduced height by up to **41.95%** | (pqac-00000008) |
| Key allele | **RHT-B1bE529K** | EMS-induced missense change in the **PFYRE** motif; hypomorphic suppressor of Rht-B1b | Partially suppresses semi-dwarfism; increased height by **19 cm (~21%)** vs RHT-B1b, compared with **33 cm (~34%)** for RHT-B1a vs RHT-B1b; increased coleoptile/seedling shoot/internode lengths without significant yield-component penalties in that study | (pqac-00000010) |
| 2023–2024 application | **CRISPR/SpCas9 knockout of Rht-B1b** | Functional validation of Rht-B1b in coleoptile development | **Rht-B1b-KO increased coleoptile length** relative to null transgenic plants | (pqac-00000009, pqac-00000011) |
| 2023–2024 application | **Rht-B1b overexpression** | Gain-of-function transgenic validation | Overexpression **reduced coleoptile length**, supporting direct repression of elongation by the semi-dwarf DELLA allele | (pqac-00000009, pqac-00000011) |
| 2023–2024 application | **KASP marker deployment** | Diagnostic KASP markers used for **Rht-B1, Rht-D1, Rht13, Rht25, Rht26**; a new **Rht-B1p KASP** marker was developed in 2024 | In 199 Pakistani cultivars, **Rht-B1b frequency = 69.6%**; **Rht26 = 58.5%**; rare Rht25c/d/e frequencies **1.5%, 1.0%, 0.5%** | (pqac-00000015) |
| 2024 breeding / population evidence | Yield and deployment context | Semi-dwarf DELLA alleles remain major breeding loci but can be environment-dependent | In a 299-genotype Nordic–Baltic spring wheat panel across **12 trials**, **no beneficial grain-yield effect** of **Rht-B1b/Rht-D1b** was observed; carriers were generally low yielding in that germplasm; in the same study, chr4B and chr4D DELLA markers explained up to **17.95%** and **29.16%** of PH variance, respectively | (pqac-00000017, pqac-00000018, pqac-00000019) |


*Table: This table compacts the identity, domain structure, major alleles, mechanisms, phenotypic effects, and recent 2023-2024 applications for wheat RHT-1/DELLA proteins. It is useful as a quick reference linking molecular lesions to GA-signaling consequences and breeding-relevant quantitative outcomes.*