Abstract
The role of the Arabidopsis transcription factor LONG HYPOCOTYL 5 (HY5) in promoting photomorphogenic development has been extensively characterized. Although the current model for HY5 action largely explains its role in this process, it does not adequately address the root phenotype observed in hy5 mutants. In our search for common mechanisms underlying all hy5 traits, we found that they are partly the result of an altered balance of signaling through the plant hormones auxin and cytokinin. hy5 mutants are resistant to cytokinin application, and double mutant analyses indicate that a decrease in auxin signaling moderates hy5 phenotypes. Microarray analyses and semiquantitative RT-PCR indicate that two negative regulators of auxin signaling, AUXIN RESISTANT 2 (AXR2)/INDOLE ACETIC ACID 7 (IAA7) and SOLITARY ROOT (SLR)/IAA14, are underexpressed in hy5 mutants. The promoters of these genes contain a putative HY5 binding site, and in line with this observation, HY5 can bind to the promoter of AXR2 in vitro. Increased AXR2 expression in a hy5 background partially rescues the elongated hypocotyl phenotype. In summary, it appears that auxin signaling is elevated in hy5 mutants because HY5 promotes the expression of negative regulators of auxin signaling, thereby linking hormone and light signaling pathways.
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Claims 9
Claim · model-written summary
hy5 mutants are resistant to cytokinin application.
- Taxon
- Arabidopsis
Arabidopsist0 - Material
- hy5 mutantse1
- Treatment
- cytokinin applicatione1
- Outcome
- resistante1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis transcription factor HY5”
e1“hy5 mutants are resistant to cytokinin application”
Claim · model-written summary
A decrease in auxin signaling moderates hy5 phenotypes.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- hy5 phenotypese2
- Qualifier
- a decrease in auxin signalinge2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis transcription factor HY5”
e2“double mutant analyses indicate that a decrease in auxin signaling moderates hy5 phenotypes”
Claim · model-written summary
AXR2 is underexpressed in hy5 mutants.
- Taxon
- ArabidopsisArabidopsist0
- Material
- hy5 mutantse3
- Gene
- AXR2e3
- Outcome
- underexpressede3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis transcription factor HY5”
e3“Microarray analyses and semiquantitative RT-PCR indicate that two negative regulators of auxin signaling, AUXIN RESISTANT 2 (AXR2)/INDOLE ACETIC ACID 7 (IAA7) and SOLITARY ROOT (SLR)/IAA14, are underexpressed in hy5 mutants”
Claim · model-written summary
SLR is underexpressed in hy5 mutants.
- Taxon
- ArabidopsisArabidopsist0
- Material
- hy5 mutantse3
- Gene
- SLRe3
- Outcome
- underexpressede3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis transcription factor HY5”
e3“Microarray analyses and semiquantitative RT-PCR indicate that two negative regulators of auxin signaling, AUXIN RESISTANT 2 (AXR2)/INDOLE ACETIC ACID 7 (IAA7) and SOLITARY ROOT (SLR)/IAA14, are underexpressed in hy5 mutants”
Claim · model-written summary
HY5 can bind to the promoter of AXR2 in vitro.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AXR2e4
- Outcome
- HY5 can bind to the promoter of AXR2e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis transcription factor HY5”
e4“The promoters of these genes contain a putative HY5 binding site, and in line with this observation, HY5 can bind to the promoter of AXR2 in vitro”
Claim · model-written summary
The promoters of the AXR2 and SLR genes contain a putative HY5 binding site.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- contain a putative HY5 binding sitee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis transcription factor HY5”
e4“The promoters of these genes contain a putative HY5 binding site”
Claim · model-written summary
Increased AXR2 expression in a hy5 background partially rescues the elongated hypocotyl phenotype.
- Taxon
- ArabidopsisArabidopsist0
- Material
- hy5 backgrounde5
- Organ / stage
- hypocotyle5
- Treatment
- Increased AXR2 expressione5
- Gene
- AXR2e5
- Outcome
- elongated hypocotyl phenotypee5
- Direction
- partially rescuese5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis transcription factor HY5”
e5“Increased AXR2 expression in a hy5 background partially rescues the elongated hypocotyl phenotype”
Claim · model-written summary
The hy5 traits are partly the result of an altered balance of signaling through the hormones auxin and cytokinin.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- hy5 traitse6
- Qualifier
- altered balance of signaling through the plant hormones auxin and cytokinine6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis transcription factor HY5”
e6“common mechanisms underlying all hy5 traits, we found that they are partly the result of an altered balance of signaling through the plant hormones auxin and cytokinin”
Claim · model-written summary
Auxin signaling is elevated in hy5 mutants because HY5 promotes expression of negative regulators of auxin signaling.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- auxin signaling is elevated in hy5 mutantse7
- Qualifier
- HY5 promotes the expression of negative regulators of auxin signalinge7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Arabidopsis transcription factor HY5”
e7“auxin signaling is elevated in hy5 mutants because HY5 promotes the expression of negative regulators of auxin signaling”