Abstract
Substantial evidence indicates that amino acid conjugates of indole-3-acetic acid (IAA) function in auxin homeostasis, yet the plant enzymes involved in their biosynthesis have not been identified. We tested whether several Arabidopsis thaliana enzymes that are related to the auxin-induced soybean (Glycine max) GH3 gene product synthesize IAA-amino acid conjugates. In vitro reactions with six recombinant GH3 enzymes produced IAA conjugates with several amino acids, based on thin layer chromatography. The identity of the Ala, Asp, Phe, and Trp conjugates was verified by gas chromatography-mass spectrometry. Insertional mutations in GH3.1, GH3.2, GH3.5, and GH3.17 resulted in modestly increased sensitivity to IAA in seedling root. Overexpression of GH3.6 in the activation-tagged mutant dfl1-D did not significantly alter IAA level but resulted in 3.2- and 4.5-fold more IAA-Asp than in wild-type seedlings and mature leaves, respectively. In addition to IAA, dfl1-D was less sensitive to indole-3-butyric acid and naphthaleneacetic acid, consistent with the fact that GH3.6 was active on each of these auxins. By contrast, GH3.6 and the other five enzymes tested were inactive on halogenated auxins, and dfl1-D was not resistant to these. This evidence establishes that several GH3 genes encode IAA-amido synthetases, which help to maintain auxin homeostasis by conjugating excess IAA to amino acids.
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Claims 12
Claim · model-written summary
Six GH3 enzymes produced IAA amino acid conjugates in vitro.
- Taxon
- Arabidopsis
Arabidopsist0 - Gene
- GH3 enzymese0
- Outcome
- IAA conjugatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In vitro reactions with six recombinant GH3 enzymes produced IAA conjugates with several amino acids”
t0“Arabidopsis”
Claim · model-written summary
Ala, Asp, Phe, and Trp conjugate identities were verified.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- Ala, Asp, Phe, and Trp conjugatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The identity of the Ala, Asp, Phe, and Trp conjugates was verified by gas chromatography-mass spectrometry”
t0“Arabidopsis”
Claim · model-written summary
Mutations in four GH3 genes modestly increased seedling root sensitivity to IAA.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- seedling roote0
- Treatment
- Insertional mutationse0
- Gene
- GH3.1, GH3.2, GH3.5, and GH3.17e0
- Outcome
- sensitivity to IAAe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Insertional mutations in GH3.1, GH3.2, GH3.5, and GH3.17 resulted in modestly increased sensitivity to IAA in seedling root”
t0“Arabidopsis”
Claim · model-written summary
GH3.6 overexpression did not significantly alter IAA level.
- Taxon
- ArabidopsisArabidopsist0
- Material
- dfl1-De0
- Treatment
- Overexpression of GH3.6e0
- Gene
- GH3.6e0
- Outcome
- IAA levele0
- Direction
- did not significantly altere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Overexpression of GH3.6 in the activation-tagged mutant dfl1-D did not significantly alter IAA level”
t0“Arabidopsis”
Claim · model-written summary
GH3.6 overexpression produced 3.2-fold more IAA-Asp in seedlings.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- seedlingse0
- Outcome
- IAA-Aspe0
- Direction
- moree0
- Value
- 3.2-e0
- Comparator
- wild-typee0
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“resulted in 3.2- and 4.5-fold more IAA-Asp than in wild-type seedlings and mature leaves, respectively”
t0“Arabidopsis”
Claim · model-written summary
GH3.6 overexpression produced 4.5-fold more IAA-Asp in mature leaves.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- mature leavese0
- Outcome
- IAA-Aspe0
- Direction
- moree0
- Value
- 4.5-folde0
- Comparator
- wild-typee0
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“resulted in 3.2- and 4.5-fold more IAA-Asp than in wild-type seedlings and mature leaves, respectively”
t0“Arabidopsis”
Claim · model-written summary
dfl1-D was less sensitive to indole-3-butyric acid.
- Taxon
- ArabidopsisArabidopsist0
- Material
- dfl1-De0
- Outcome
- sensitive to indole-3-butyric acide0
- Direction
- lesse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“dfl1-D was less sensitive to indole-3-butyric acid and naphthaleneacetic acid”
t0“Arabidopsis”
Claim · model-written summary
dfl1-D was less sensitive to naphthaleneacetic acid.
- Taxon
- ArabidopsisArabidopsist0
- Material
- dfl1-De0
- Outcome
- naphthaleneacetic acide0
- Direction
- lesse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“dfl1-D was less sensitive to indole-3-butyric acid and naphthaleneacetic acid”
t0“Arabidopsis”
Claim · model-written summary
GH3.6 was active on these auxins.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- GH3.6e0
- Outcome
- active on each of these auxinse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GH3.6 was active on each of these auxins”
t0“Arabidopsis”
Claim · model-written summary
The tested GH3 enzymes were inactive on halogenated auxins.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- GH3.6e0
- Outcome
- inactive on halogenated auxinse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GH3.6 and the other five enzymes tested were inactive on halogenated auxins”
t0“Arabidopsis”
Claim · model-written summary
dfl1-D was not resistant to halogenated auxins.
- Taxon
- ArabidopsisArabidopsist0
- Material
- dfl1-De0
- Outcome
- not resistant to thesee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“dfl1-D was not resistant to these”
t0“Arabidopsis”
Claim · model-written summary
Several GH3 genes encode IAA-amido synthetases that maintain auxin homeostasis by conjugation.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- GH3 genese0
- Outcome
- auxin homeostasise0
- Qualifier
- conjugating excess IAA to amino acidse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“several GH3 genes encode IAA-amido synthetases, which help to maintain auxin homeostasis by conjugating excess IAA to amino acids”
t0“Arabidopsis”
The same questions in other papers
loss of function · molecular: metabolites · ArabidopsisPositive and negative results
141 papers in the same direction as this paper · 37 in the opposite direction
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