Abstract
Seed germination is regulated by many signals. We investigated the possible involvement of a heterotrimeric G protein complex in this signal regulation. Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA), have increased sensitivity to high levels of Glc, and have a near-wild-type germination response to abscisic acid and ethylene, indicating that GPA1 does not directly couple these signals in germination control. Seeds ectopically expressing GPA1 are at least a million-fold more responsive to GA, yet still require GA for germination. We conclude that the GPA1 indirectly operates on the GA pathway to control germination by potentiation. We propose that this potentiation is directly mediated by brassinosteroids (BR) because the BR response and synthesis mutants, bri1-5 and det2-1, respectively, share the same GA sensitivity as gpa1 seeds. Furthermore, gpa1 seeds are completely insensitive to brassinolide rescue of germination when the level of GA in seeds is reduced. A lack of BR responsiveness is also apparent in gpa1 roots and hypocotyls suggesting that BR signal transduction is likely coupled by a heterotrimeric G protein at various points in plant development.
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Claims 11
Claim · model-written summary
GPA1-null seeds are 100-fold less responsive to gibberellic acid.
- Taxon
- Arabidopsis
Arabidopsise0 - Material
- protein null mutatione0
- Gene
- GPA1e0
- Outcome
- responsive to gibberellic acid (GA)e0
- Direction
- less responsivee0
- Value
- 100-folde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
GPA1-null seeds have increased sensitivity to high glucose.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- GPA1e1
- Outcome
- sensitivity to high levels of Glce0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“have increased sensitivity to high levels of Glc”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
GPA1-null seeds show a near-wild-type response to abscisic acid and ethylene.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- GPA1e1
- Outcome
- germination response to abscisic acid and ethylenee0
- Direction
- near-wild-typee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“have a near-wild-type germination response to abscisic acid and ethylene”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
Ectopic GPA1 expression makes seeds at least a million-fold more responsive to GA.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- ectopically expressing GPA1e0
- Gene
- GPA1e0
- Outcome
- responsive to GAe0
- Direction
- more responsivee0
- Value
- at least a million-folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seeds ectopically expressing GPA1 are at least a million-fold more responsive to GA”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
Ectopic GPA1 seeds still require GA for germination.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- GPA1e1
- Outcome
- require GA for germinatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“yet still require GA for germination”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
BR response and synthesis mutants share the GA sensitivity of gpa1 seeds.
- Taxon
- ArabidopsisArabidopsist0
- Material
- bri1-5 and det2-1e0
- Outcome
- same GA sensitivity as gpa1 seedse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the BR response and synthesis mutants, bri1-5 and det2-1, respectively, share the same GA sensitivity as gpa1 seeds”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
gpa1 seeds are insensitive to brassinolide rescue when seed GA is reduced.
- Taxon
- ArabidopsisArabidopsist0
- Material
- gpa1 seedse0
- Treatment
- brassinolidee0
- Outcome
- rescue of germinatione0
- Direction
- completely insensitivee0
- Qualifier
- when the level of GA in seeds is reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“gpa1 seeds are completely insensitive to brassinolide rescue of germination when the level of GA in seeds is reduced”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
gpa1 roots and hypocotyls lack BR responsiveness.
- Taxon
- ArabidopsisArabidopsist0
- Material
- gpa1e0
- Organ / stage
- roots and hypocotylse0
- Outcome
- lack of BR responsivenesse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A lack of BR responsiveness is also apparent in gpa1 roots and hypocotyls”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
Authors conclude GPA1 indirectly potentiates GA control of germination.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- GPA1e0
- Outcome
- control germinatione0
- Qualifier
- by potentiatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the GPA1 indirectly operates on the GA pathway to control germination by potentiation”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
Authors propose that brassinosteroids directly mediate this potentiation.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- brassinosteroids (BR)e0
- Outcome
- potentiatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this potentiation is directly mediated by brassinosteroids (BR)”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
Claim · model-written summary
Authors suggest a heterotrimeric G protein couples BR signaling at multiple developmental points.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- heterotrimeric G proteine0
- Outcome
- BR signal transductione0
- Qualifier
- at various points in plant developmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“BR signal transduction is likely coupled by a heterotrimeric G protein at various points in plant development”
t0“Arabidopsis”
e1“Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA)”
The same questions in other papers
brassinolide · growth · ArabidopsisPositive and negative results
4 papers in the same direction as this paper · 10 in the opposite direction
- positive
- positive
- positive
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See all 15 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.