Abstract
Sugar-mediated regulation of hormone signaling is crucial for optimizing growth under normal conditions and ensuring survival during environmental stress. Previous studies have shown that sugar starvation induces the degradation of BRASSINAZOLE RESISTANT 1 (BZR1), the master transcription factor of the brassinosteroid (BR) signaling pathway, thereby inhibiting growth. However, the molecular mechanism linking sugar signaling to BZR1 degradation remains unknown. To identify proteins that mediate starvation-induced BZR1 degradation, we performed a quantitative proteomic analysis of the BZR1 interactome under starvation conditions and identified UBIQUITIN PROTEIN LIGASE 3 (UPL3) as a sugar-regulated protein that promotes BZR1 degradation and regulates growth and survival in response to sugar availability. upl3 mutants showed increased BZR1 accumulation and larger seedling size compared to the wild type under sugar-limiting conditions, but not when grown on sugar-containing medium, which indicates that UPL3 mediates BZR1 degradation and growth inhibition under sugar-limited conditions. Although upl3 mutations promoted growth under short-term starvation, they substantially reduced survival under long-term starvation. The enhanced growth phenotype of upl3 was also observed when target of rapamycin (TOR) was inactivated, but not when BR biosynthesis was blocked, suggesting that UPL3 acts downstream of sugar-TOR signaling to regulate BZR1 degradation. Furthermore, UPL3 protein levels increased post-transcriptionally in response to starvation and TOR inhibition, and decreased upon sugar treatment. Our study identifies UPL3 as a key molecular link between sugar signaling and BR signaling. We propose that sugar-TOR signaling inhibits UPL3 to promote BZR1 accumulation and growth, thereby optimizing plant growth and survival in response to sugar availability.
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Claims 11
Claim · model-written summary
upl3 mutants showed increased BZR1 accumulation compared with wild type under sugar-limiting conditions.
- Taxon
- Arabidopsis
Arabidopsist0 - Material
- upl3 mutantse1
- Treatment
- sugar-limiting conditionse1
- Gene
- BZR1e1
- Outcome
- BZR1 accumulatione1
- Direction
- increasede1
- Comparator
- wild typee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e1“upl3 mutants showed increased BZR1 accumulation and larger seedling size compared to the wild type under sugar-limiting conditions”
Claim · model-written summary
upl3 mutants had larger seedlings than wild type under sugar-limiting conditions.
- Taxon
- ArabidopsisArabidopsist0
- Material
- upl3 mutantse1
- Treatment
- sugar-limiting conditionse1
- Outcome
- seedling sizee1
- Direction
- largere1
- Comparator
- wild typee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e1“upl3 mutants showed increased BZR1 accumulation and larger seedling size compared to the wild type under sugar-limiting conditions”
Claim · model-written summary
The upl3 seedling phenotype was not present when plants were grown on sugar-containing medium.
- Taxon
- ArabidopsisArabidopsist0
- Material
- upl3e1
- Treatment
- sugar-containing mediume2
- Outcome
- seedling sizee1
- Direction
- no_changeinferrede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e1“upl3 mutants showed increased BZR1 accumulation and larger seedling size compared to the wild type under sugar-limiting conditions”
e2“but not when grown on sugar-containing medium”
Claim · model-written summary
upl3 mutations promoted growth under short-term starvation.
- Taxon
- ArabidopsisArabidopsist0
- Material
- upl3 mutationse3
- Treatment
- short-term starvatione3
- Outcome
- growthe3
- Direction
- promotede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e3“Although upl3 mutations promoted growth under short-term starvation, they substantially reduced survival under long-term starvation”
Claim · model-written summary
upl3 mutations substantially reduced survival under long-term starvation.
- Taxon
- ArabidopsisArabidopsist0
- Material
- upl3 mutationse3
- Treatment
- long-term starvatione3
- Outcome
- survivale3
- Direction
- substantially reducede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e3“Although upl3 mutations promoted growth under short-term starvation, they substantially reduced survival under long-term starvation”
Claim · model-written summary
The enhanced growth phenotype of upl3 was also observed when TOR was inactivated.
- Taxon
- ArabidopsisArabidopsist0
- Material
- upl3e4
- Treatment
- target of rapamycin (TOR) was inactivatede4
- Outcome
- growth phenotypee4
- Direction
- enhancede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e4“The enhanced growth phenotype of upl3 was also observed when target of rapamycin (TOR) was inactivated”
Claim · model-written summary
The enhanced growth phenotype of upl3 was not observed when BR biosynthesis was blocked.
- Taxon
- ArabidopsisArabidopsist0
- Material
- upl3e4
- Treatment
- BR biosynthesis was blockede5
- Outcome
- growth phenotypee4
- Direction
- no_changeinferrede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e4“The enhanced growth phenotype of upl3 was also observed when target of rapamycin (TOR) was inactivated”
e5“but not when BR biosynthesis was blocked”
Claim · model-written summary
UPL3 protein levels increased post-transcriptionally in response to starvation and TOR inhibition.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- starvation and TOR inhibitione6
- Gene
- UPL3e6
- Outcome
- UPL3 protein levelse6
- Direction
- increasede6
- Qualifier
- post-transcriptionallye6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e6“UPL3 protein levels increased post-transcriptionally in response to starvation and TOR inhibition, and decreased upon sugar treatment”
Claim · model-written summary
UPL3 protein levels decreased upon sugar treatment.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- sugar treatmente6
- Gene
- UPL3e6
- Outcome
- UPL3 protein levelse6
- Direction
- decreasede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e6“UPL3 protein levels increased post-transcriptionally in response to starvation and TOR inhibition, and decreased upon sugar treatment”
Claim · model-written summary
UPL3 mediates BZR1 degradation and growth inhibition under sugar-limited conditions.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- UPL3e0
- Outcome
- BZR1 degradatione1
- Qualifier
- under sugar-limited conditionse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e0“identified UBIQUITIN PROTEIN LIGASE 3 (UPL3) as a sugar-regulated protein that promotes BZR1 degradation”
e1“UPL3 mediates BZR1 degradation and growth inhibition under sugar-limited conditions”
Claim · model-written summary
UPL3 acts downstream of sugar-TOR signaling to regulate BZR1 degradation.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- UPL3e7
- Outcome
- BZR1 degradatione7
- Qualifier
- downstream of sugar-TOR signalinge7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“in Arabidopsis”
e7“UPL3 acts downstream of sugar-TOR signaling to regulate BZR1 degradation”
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See all 17 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.