Abstract
The C-Repeat Binding Factor (CBF) cold-response pathway has a prominent role in cold acclimation, the process whereby certain plants increase tolerance to freezing in response to low nonfreezing temperatures. In Arabidopsis, the CBF pathway is characterized by rapid induction of the C-Repeat Binding Factor 1 (CBF1), CBF2, and CBF3 genes, which encode transcriptional activators, followed by induction of the CBF-targeted genes known as the "CBF regulon." Expression of the CBF regulon results in an increase in freezing tolerance. Previous studies established that CBF1, CBF2, and CBF3 are subject to circadian regulation and that their cold induction is gated by the circadian clock. Here we present the results of genetic analysis and ChIP experiments indicating that both these forms of regulation involve direct positive action of two transcription factors that are core components of the clock, i.e., Circadian Clock-Associated 1 (CCA1) and Late Elongated Hypocotyl (LHY). In plants carrying the cca1-11/lhy-21 double mutation, cold induction of CBF1, CBF2, and CBF3 was greatly impaired, and circadian regulation of CBF1 and CBF3 was essentially eliminated; circadian regulation of CBF2 continued, although with significantly reduced amplitude. Circadian regulation and cold induction of three CBF regulon genes, i.e., COld-regulated Gene15a (COR15A), COR47, and COR78, also were greatly diminished in plants carrying the cca1-11/lhy-21 double mutation. Furthermore, the cca1-11/lhy-21 double mutation resulted in impaired freezing tolerance in both nonacclimated and cold-acclimated plants. These results indicate that CCA1/LHY-mediated output from the circadian clock contributes to plant cold tolerance through regulation of the CBF cold-response pathway.
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Claims 7
Claim · model-written summary
The cca1-11/lhy-21 double mutation greatly impaired cold induction of CBF1, CBF2, and CBF3.
- Taxon
- Arabidopsis
Arabidopsist0 - Material
- cca1-11/lhy-21 double mutatione0
- Treatment
- cca1-11/lhy-21 double mutatione0
- Gene
- CBF1, CBF2, and CBF3e0
- Outcome
- cold induction of CBF1, CBF2, and CBF3e0
- Direction
- greatly impairede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In plants carrying the cca1-11/lhy-21 double mutation, cold induction of CBF1, CBF2, and CBF3 was greatly impaired”
t0“Arabidopsis”
Claim · model-written summary
The double mutation essentially eliminated circadian regulation of CBF1 and CBF3.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- CIRCADIAN CLOCK-ASSOCIATED 1t0
- Outcome
- circadian regulation of CBF1 and CBF3e0
- Direction
- essentially eliminatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“circadian regulation of CBF1 and CBF3 was essentially eliminated”
t0“CIRCADIAN CLOCK-ASSOCIATED 1 and LATE ELONGATED HYPOCOTYL regulate expression of the C-REPEAT BINDING FACTOR (CBF) pathway in Arabidopsis”
Claim · model-written summary
Circadian regulation of CBF2 continued with significantly reduced amplitude in double mutants.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- CIRCADIAN CLOCK-ASSOCIATED 1t0
- Outcome
- circadian regulation of CBF2e0
- Direction
- reducede0
- Qualifier
- significantly reduced amplitudee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“circadian regulation of CBF2 continued, although with significantly reduced amplitude.”
t0“CIRCADIAN CLOCK-ASSOCIATED 1 and LATE ELONGATED HYPOCOTYL regulate expression of the C-REPEAT BINDING FACTOR (CBF) pathway in Arabidopsis”
Claim · model-written summary
The double mutation greatly diminished circadian regulation and cold induction of COR15A, COR47, and COR78.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- cca1-11/lhy-21 double mutatione0
- Gene
- COR15Ae0
- Outcome
- Circadian regulation and cold induction of three CBF regulon genese0
- Direction
- greatly diminishede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Circadian regulation and cold induction of three CBF regulon genes, i.e., COld-regulated Gene15a (COR15A), COR47, and COR78, also were greatly diminished in plants carrying the cca1-11/lhy-21 double mutation.”
t0“Arabidopsis”
Claim · model-written summary
The double mutation impaired freezing tolerance in nonacclimated and cold-acclimated plants.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- cca1-11/lhy-21 double mutatione0
- Outcome
- freezing tolerancee0
- Direction
- impairede0
- Qualifier
- both nonacclimated and cold-acclimated plantse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the cca1-11/lhy-21 double mutation resulted in impaired freezing tolerance in both nonacclimated and cold-acclimated plants.”
t0“Arabidopsis”
Claim · model-written summary
CCA1 and LHY directly promote circadian and cold induction regulation of CBF genes.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- Circadian Clock-Associated 1 (CCA1) and Late Elongated Hypocotyl (LHY)e0
- Outcome
- both these forms of regulatione0
- Direction
- positivee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both these forms of regulation involve direct positive action of two transcription factors that are core components of the clock, i.e., Circadian Clock-Associated 1 (CCA1) and Late Elongated Hypocotyl (LHY).”
t0“Arabidopsis”
Claim · model-written summary
CCA1/LHY clock output contributes to cold tolerance through CBF pathway regulation.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- CCA1/LHYe0
- Outcome
- plant cold tolerancee0
- Qualifier
- through regulation of the CBF cold-response pathwaye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CCA1/LHY-mediated output from the circadian clock contributes to plant cold tolerance through regulation of the CBF cold-response pathway.”
t0“Arabidopsis”
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