Abstract
GIGANTEA (GI) is a nuclear protein involved in the promotion of flowering by long days, in light input to the circadian clock, and in seedling photomorphogenesis under continuous red light but not far-red light (FR). Here, we report that in Arabidopsis (Arabidopsis thaliana) different alleles of gi have defects in the hypocotyl-growth and cotyledon-unfolding responses to hourly pulses of FR, a treatment perceived by phytochrome A (phyA). This phenotype is rescued by overexpression of GI. The very-low-fluence response of seed germination was also reduced in gi. Since the circadian clock modulates many light responses, we investigated whether these gi phenotypes were due to alterations in the circadian system or light signaling per se. In experiments where FR pulses were given to dark-incubated seeds or seedlings at different times of the day, gi showed reduced seed germination, cotyledon unfolding, and activity of a luciferase reporter fused to the promoter of a chlorophyll a/b-binding protein gene; however, rhythmic sensitivity was normal in these plants. We conclude that while GI does not affect the high-irradiance responses of phyA, it does affect phyA-mediated very-low-fluence responses via mechanisms that do not obviously involve its circadian functions.
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Claims 6
Claim · model-written summary
gi alleles had defective hypocotyl growth and cotyledon unfolding responses to hourly far-red pulses.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae0 - Treatment
- hourly pulses of FRe0
- Gene
- gie0
- Outcome
- hypocotyl-growth and cotyledon-unfolding responsese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in Arabidopsis (Arabidopsis thaliana) different alleles of gi have defects in the hypocotyl-growth and cotyledon-unfolding responses to hourly pulses of FR”
Claim · model-written summary
GI overexpression rescued the gi light-response phenotype.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- overexpression of GIe0
- Gene
- GIe0
- Outcome
- phenotypee0
- Comparator
- gie1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This phenotype is rescued by overexpression of GI”
e1“in Arabidopsis (Arabidopsis thaliana) different alleles of gi have defects in the hypocotyl-growth and cotyledon-unfolding responses to hourly pulses of FR”
Claim · model-written summary
Very-low-fluence germination response was reduced in gi.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Gene
- gie0
- Outcome
- very-low-fluence response of seed germinatione0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The very-low-fluence response of seed germination was also reduced in gi”
e1“in Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Far-red pulses reduced gi seed germination and cotyledon unfolding and reporter activity.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- FR pulsese0
- Gene
- gie0
- Outcome
- seed germination, cotyledon unfolding, and activity of a luciferase reportere0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“FR pulses were given to dark-incubated seeds or seedlings at different times of the day, gi showed reduced seed germination, cotyledon unfolding, and activity of a luciferase reporter fused to the promoter of a chlorophyll a/b-binding protein gene”
e1“in Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Rhythmic light sensitivity remained normal in gi plants.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Outcome
- rhythmic sensitivity was normale0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“rhythmic sensitivity was normal in these plants”
e1“in Arabidopsis (Arabidopsis thaliana)”
Claim · model-written summary
Authors conclude GI affects phyA-mediated very-low-fluence responses without an obvious circadian mechanism.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Gene
- GIe0
- Outcome
- phyA-mediated very-low-fluence responsese0
- Qualifier
- mechanisms that do not obviously involve its circadian functionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GI does not affect the high-irradiance responses of phyA, it does affect phyA-mediated very-low-fluence responses via mechanisms that do not obviously involve its circadian functions”
e1“in Arabidopsis (Arabidopsis thaliana)”
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