MYB28 (HAG1/PMG1, At5g61420) is a nuclear R2R3-MYB transcription factor of Arabidopsis thaliana that is the dominant positive regulator of methionine-derived (aliphatic) glucosinolate biosynthesis. Through its two N-terminal Myb DNA-binding repeats it binds promoters of aliphatic glucosinolate genes (side-chain elongation, core-structure and side-chain modification enzymes) and transactivates them, acting together with the paralogs MYB29 and MYB76 and with the jasmonate-responsive bHLH factors MYC2, MYC3 and MYC4. MYB28 is required for basal and especially long-chain aliphatic glucosinolate production and is sufficient to drive glucosinolate synthesis when overexpressed; MYB28/MYB29 double mutants lack aliphatic glucosinolates entirely. Its expression in leaves, inflorescences and trichomes responds to wounding, glucose, sulfur status, hormones and herbivory, and via its glucosinolate output it contributes to resistance against generalist insects, necrotrophic fungi and bacteria.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000976 transcription cis-regulatory region binding | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA-predicted transcription cis-regulatory region binding; consistent with the experimental Y1H promoter-binding rows and the R2R3 Myb DNA-binding domains. Reason: MYB28 binds promoters of aliphatic glucosinolate genes in yeast one-hybrid assays (PMID:25352272), so the ARBA prediction agrees with direct evidence for this gene; same claim as the IPI rows. Supporting Evidence: PMID:25352272 52 TF s that interacted with at least the same number of promoters as MYB28, which has been validated to interact with these promoters |
| GO:0000976 transcription cis-regulatory region binding | IPI PMID:25352272 Promoter-based integration in plant defense regulation. | ACCEPT | Summary: Yeast one-hybrid screen with aliphatic glucosinolate pathway promoters; MYB28 bound promoters of pathway genes (With/From lists target loci such as GSTF11, IPMI, AOP2, BAT5). Reason: Direct promoter-binding evidence for the gene from a systematic Y1H screen whose authors state MYB28 is validated to interact with these promoters; this DNA binding underlies its transcription activator activity. Supporting Evidence: PMID:25352272 52 TF s that interacted with at least the same number of promoters as MYB28, which has been validated to interact with these promoters |
| GO:0000976 transcription cis-regulatory region binding | IPI PMID:25533953 An Arabidopsis gene regulatory network for secondary cell wa... | ACCEPT | Summary: Yeast one-hybrid gene regulatory network screen (secondary cell wall study) recording MYB28 binding to promoters including aliphatic glucosinolate genes and AT5G17420. Reason: MYB28 does not appear in the cached main text (interactions are in supplementary data), but the curator-assigned Y1H promoter binding is the same activity independently established for MYB28 in PMID:25352272; deferring to the curator. Supporting Evidence: PMID:25352272 52 TF s that interacted with at least the same number of promoters as MYB28, which has been validated to interact with these promoters |
| GO:0000976 transcription cis-regulatory region binding | IPI PMID:30356219 Transcriptional regulation of nitrogen-associated metabolism... | ACCEPT | Summary: Yeast one-hybrid nitrogen-metabolism network screen recording MYB28 binding to the AT2G41225 promoter. Reason: Abstract-only paper; the Y1H promoter binding recorded by the curator is consistent with MYB28 cis-regulatory binding activity established elsewhere (PMID:25352272). The specific target is peripheral to the core aliphatic glucosinolate role but the molecular function claim is the same as the other rows. Supporting Evidence: PMID:25352272 52 TF s that interacted with at least the same number of promoters as MYB28, which has been validated to interact with these promoters |
| GO:0003700 DNA-binding transcription factor activity | ISS PMID:11118137 Arabidopsis transcription factors: genome-wide comparative a... | MODIFY | Summary: Genome-wide transcription factor classification assigning DNA-binding transcription factor activity by R2R3-MYB domain similarity. Reason: Correct but general. MYB28 transactivates aliphatic glucosinolate biosynthetic promoters and is a positive regulator (transactivation and cotransformation assays, knockout/overexpression), so the activity is better captured by its child DNA-binding transcription activator activity. The RNA polymerase II-specific child is not used, because polymerase specificity has not been tested. Proposed replacements: DNA-binding transcription activator activity Supporting Evidence: PMID:17521412 In a screen for the trans-activation potential of various transcription factors toward glucosinolate biosynthetic genes, we could identify the HAG1 (HIGH ALIPHATIC GLUCOSINOLATE 1, also referred to as MYB28) gene as a positive regulator of aliphatic methionine-derived glucosinolates PMID:18042203 HAG1/MYB28, HAG2/MYB76 and HAG3/MYB29 reciprocally transactivated each other in the control of aliphatic glucosinolate biosynthesis |
| GO:0003700 DNA-binding transcription factor activity | NAS PMID:17420480 Omics-based identification of Arabidopsis Myb transcription ... | MODIFY | Summary: Author statement in the omics paper that MYB28/PMG1 is an R2R3-Myb transcription factor regulating aliphatic glucosinolate biosynthesis. Reason: Same claim as the ISS row; the evidence (positive regulation of target biosynthetic genes, transactivation) supports the more specific DNA-binding transcription activator activity. Proposed replacements: DNA-binding transcription activator activity Supporting Evidence: PMID:17420480 PMG1/Myb28 is apparently a master transcription factor, generally regulating the pathway from Met to aliphatic GSLs, and is necessary and sufficient for the biosynthesis of aliphatic GSLs at a basal level in Arabidopsis PMID:17521412 In a screen for the trans-activation potential of various transcription factors toward glucosinolate biosynthetic genes, we could identify the HAG1 (HIGH ALIPHATIC GLUCOSINOLATE 1, also referred to as MYB28) gene as a positive regulator of aliphatic methionine-derived glucosinolates |
| GO:0005634 nucleus | IDA PMID:17521412 The R2R3-MYB transcription factor HAG1/MYB28 is a regulator ... | ACCEPT | Summary: Nuclear localization (IDA). Reason: MYB28 is a nuclear transcription factor; UniProt records nuclear localization with experimental evidence from PMID:17521412, consistent with its DNA-binding transcription activator role. Supporting Evidence: file:ARATH/MYB28/MYB28-uniprot.txt SUBCELLULAR LOCATION: Nucleus |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: Nuclear localization (IEA). Reason: MYB28 is a nuclear transcription factor; UniProt records nuclear localization with experimental evidence from PMID:17521412, consistent with its DNA-binding transcription activator role. Supporting Evidence: file:ARATH/MYB28/MYB28-uniprot.txt SUBCELLULAR LOCATION: Nucleus |
| GO:0005634 nucleus | ISM GO_REF:0000122 | ACCEPT | Summary: Nuclear localization (ISM). Reason: MYB28 is a nuclear transcription factor; UniProt records nuclear localization with experimental evidence from PMID:17521412, consistent with its DNA-binding transcription activator role. Supporting Evidence: file:ARATH/MYB28/MYB28-uniprot.txt SUBCELLULAR LOCATION: Nucleus |
| GO:0006355 regulation of DNA-templated transcription | IEP PMID:17420480 Omics-based identification of Arabidopsis Myb transcription ... | MODIFY | Summary: Regulation of DNA-templated transcription, from the omics study identifying MYB28 as a regulator of aliphatic glucosinolate genes. Reason: The paper shows the direction: knockout represses and overexpression induces aliphatic glucosinolate biosynthetic gene transcription, so MYB28 positively regulates transcription; refine to positive regulation of DNA-templated transcription. Proposed replacements: positive regulation of DNA-templated transcription Supporting Evidence: PMID:17420480 the expression of most of the genes involved in aliphatic GSL biosynthesis was repressed in myb28 PMID:17420480 PMG1/Myb28 is apparently a master transcription factor, generally regulating the pathway from Met to aliphatic GSLs, and is necessary and sufficient for the biosynthesis of aliphatic GSLs at a basal level in Arabidopsis |
| GO:0006950 response to stress | IEA GO_REF:0000117 | TOO GENERAL | Summary: ARBA-predicted response to stress. Reason: True but uninformative: MYB28 expression responds to wounding and sulfur status and its glucosinolate output contributes to defense, but the more specific terms kept in this review (defense response to fungus, induced systemic resistance, cellular response to sulfur starvation) are all is_a descendants of response to stress. |
| GO:0009617 response to bacterium | IMP PMID:23073694 Metabolic and transcriptomic changes induced in Arabidopsis ... | TOO GENERAL | Summary: myb28myb29 double mutant fails to show Pseudomonas fluorescens SS101-induced resistance against Pseudomonas syringae. Reason: The same experiment is annotated to induced systemic resistance (kept here), which is_a response to bacterium; the broader term adds nothing. The effect is indirect, via glucosinolate production. Supporting Evidence: PMID:23073694 camalexin and glucosinolates are indeed required for the induction of Pst resistance by Pf .SS101 |
| GO:0009625 response to insect | IEP PMID:23144921 Water stress and aphid feeding differentially influence meta... | KEEP AS NON CORE | Summary: MYB28 transcripts were mostly down-regulated by feeding of the aphids Myzus persicae and Brevicoryne brassicae. Reason: Expression-level response to insects; real but a regulatory input to MYB28 rather than its function. Supporting Evidence: PMID:23144921 expression of genes encoding aliphatic glucosinolate biosynthesis transcription factors, i.e. MYB28, MYB29, and MYB76, was mostly down-regulated by M. persicae and B. brassicae in both water stress treatments |
| GO:0009625 response to insect | IEP PMID:40546745 Impact of Lepidopteran Oral Secretions on the Transcriptome ... | KEEP AS NON CORE | Summary: Lepidopteran oral secretions suppressed basal MYB28 expression (RNA-seq and qPCR). Reason: Expression-level response to insect-derived elicitors; non-core context for the glucosinolate regulator. Supporting Evidence: PMID:40546745 we show consistent OS‐mediated suppression of MYC4, MYB28, MYB29, MYB76 |
| GO:0009682 induced systemic resistance | IMP PMID:23073694 Metabolic and transcriptomic changes induced in Arabidopsis ... | KEEP AS NON CORE | Summary: myb28myb29 double mutant lacks rhizobacterium (Pf.SS101)-induced systemic resistance to Pst. Reason: MYB28 acts upstream of induced systemic resistance through its control of aliphatic glucosinolate production; a double-mutant phenotype, peripheral to its core transcriptional role. Supporting Evidence: PMID:23073694 camalexin and glucosinolates are indeed required for the induction of Pst resistance by Pf .SS101 |
| GO:0010438 cellular response to sulfur starvation | TAS PMID:17420480 Omics-based identification of Arabidopsis Myb transcription ... | KEEP AS NON CORE | Summary: MYB28 expression changes under sulfur deficiency, linking glucosinolate synthesis to sulfur status. Reason: MYB28 transcription responds to sulfur deficiency (reported down-regulated in PMID:17420480 and induced in PMID:23792303), which tunes sulfur allocation into glucosinolates; a regulatory input, not the core function. Supporting Evidence: PMID:17420480 Under sulfur-deficiency conditions, the expression of PMG1 / Myb28 , PMG2 / Myb29 , and ATR1 / Myb34 was down-regulated PMID:23792303 MYB28 expression was induced by sulfur deficiency |
| GO:0010439 regulation of glucosinolate biosynthetic process | IMP PMID:17420480 Omics-based identification of Arabidopsis Myb transcription ... | ACCEPT | Summary: myb28 knockout has strongly reduced aliphatic glucosinolates and biosynthetic gene expression; overexpression activates the pathway. Reason: Core process: MYB28 is the master positive transcriptional regulator of aliphatic glucosinolate biosynthesis. GO has no positive-regulation child of this term. Supporting Evidence: PMID:17420480 PMG1/Myb28 is apparently a master transcription factor, generally regulating the pathway from Met to aliphatic GSLs, and is necessary and sufficient for the biosynthesis of aliphatic GSLs at a basal level in Arabidopsis PMID:17420480 the expression of most of the genes involved in aliphatic GSL biosynthesis was repressed in myb28 |
| GO:0010439 regulation of glucosinolate biosynthetic process | IMP PMID:17521412 The R2R3-MYB transcription factor HAG1/MYB28 is a regulator ... | ACCEPT | Summary: HAG1/MYB28 gain-of-function increases and RNAi decreases aliphatic glucosinolates and biosynthetic transcripts. Reason: Core process, independently demonstrated. Supporting Evidence: PMID:17521412 In a screen for the trans-activation potential of various transcription factors toward glucosinolate biosynthetic genes, we could identify the HAG1 (HIGH ALIPHATIC GLUCOSINOLATE 1, also referred to as MYB28) gene as a positive regulator of aliphatic methionine-derived glucosinolates |
| GO:0010439 regulation of glucosinolate biosynthetic process | IMP PMID:21418358 Role of camalexin, indole glucosinolates, and side chain mod... | ACCEPT | Summary: myb28 mutant has a regulatory defect reducing long-chain aliphatic glucosinolate production. Reason: Consistent with the core regulatory role; mutant has decreased long-chain aliphatic glucosinolates. Supporting Evidence: PMID:21418358 the myb28 mutant, which has a regulatory defect resulting in decreased production of long-chained aliphatic glucosinolates |
| GO:0050832 defense response to fungus | IMP PMID:21418358 Role of camalexin, indole glucosinolates, and side chain mod... | KEEP AS NON CORE | Summary: myb28 mutant is hypersusceptible to the necrotrophic fungus Sclerotinia sclerotiorum. Reason: MYB28 acts upstream of antifungal defense through aliphatic glucosinolate-derived isothiocyanates; an indirect, non-core consequence of its regulatory role. Supporting Evidence: PMID:21418358 the myb28 mutant, which has a regulatory defect resulting in decreased production of long-chained aliphatic glucosinolates |
| GO:0051707 response to other organism | IEA GO_REF:0000117 | TOO GENERAL | Summary: ARBA-predicted response to other organism. Reason: True but uninformative; entailed by more specific terms kept in this review (defense response to fungus, induced systemic resistance, response to insect are all is_a response to other organism). |
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Download this section (compressed HTML)Q: Does MYB28 expression go up or down under sulfur deficiency? PMID:17420480 reports down-regulation and PMID:23792303 induction; does this depend on tissue, duration or sulfur regime?
Q: Is MYB28 binding to the secondary cell wall and nitrogen-network promoters found by Y1H (PMID:25533953, PMID:30356219) functional in planta?
Experiment: ChIP-seq or DAP-seq of MYB28 in leaves (with and without MYC2/3/4) to define direct aliphatic glucosinolate target promoters and the MYB28 cis-element, and test whether repression of indolic glucosinolate genes is direct.
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