Abstract
The nodulation genes of Bradyrhizobium japonicum are essential for infection and establishment of a nitrogen-fixing symbiosis. Here, we demonstrate that plant-produced isoflavones induce nodulation gene expression in a population density-dependent fashion. Nodulation gene induction is highest at a low population density and significantly reduced in more dense cultures. A quorum signal molecule in the conditioned medium of B. japonicum cultures mediates this repression. Repression in response to the quorum signal results from the induction of NolA which, in turn, induces NodD2 leading to inhibition of nod gene expression. Consistent with this, nolA-lacZ and nodD2-lacZ expression increased with increasing population density. Unlike the wild type, the ability to induce nodY-lacZ expression did not decline with population density in a NolA mutant. Normally, nod gene expression is repressed in planta (i.e. within nodules). However, expression of a nodY-GUS fusion was not repressed in a NolA mutant, suggesting that quorum-sensing control may mediate in planta repression of the nod genes. Addition of conditioned medium to cultures significantly reduced nod gene expression. Treatment of inoculant cultures with conditioned medium also reduced the ability of B. japonicum to nodulate soybean plants.
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Claims 10
Claim · model-written summary
Plant produced isoflavones induced bacterial nodulation genes in a density dependent fashion.
- Taxon
- soybean
Glycine maxt1 - Interactor
- Bradyrhizobium japonicum
Bradyrhizobium japonicumt0symbiont - Gene
- nodulation genee0
- Compound
- isoflavonese0
- Outcome
- nodulation gene expressione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“plant-produced isoflavones induce nodulation gene expression in a population density-dependent fashion.”
t0“Bradyrhizobium japonicum”
t1“soybean plants”
Claim · model-written summary
Nodulation gene induction was highest at low density and significantly reduced in dense cultures.
- Taxon
- soybeanGlycine maxt0
- Interactor
- Bradyrhizobium japonicumBradyrhizobium japonicumt1symbiont
- Outcome
- Nodulation gene inductione0
- Direction
- reducede0
- Comparator
- more dense culturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulation gene induction is highest at a low population density and significantly reduced in more dense cultures.”
t0“soybean plants”
t1“Bradyrhizobium japonicum”
Claim · model-written summary
A quorum signal in conditioned medium mediated repression of nodulation genes.
- Taxon
- soybeanGlycine maxt0
- Interactor
- B. japonicumBradyrhizobium japonicume0symbiont
- Outcome
- repressione0
- Qualifier
- quorum signal moleculee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A quorum signal molecule in the conditioned medium of B. japonicum cultures mediates this repression.”
t0“soybean plants”
Claim · model-written summary
The quorum signal induced NolA and then NodD2, inhibiting nod gene expression.
- Taxon
- soybeanGlycine maxt0
- Gene
- NolAe0
- Outcome
- inhibition of nod gene expressione0
- Qualifier
- induces NodD2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Repression in response to the quorum signal results from the induction of NolA which, in turn, induces NodD2 leading to inhibition of nod gene expression.”
t0“soybean plants”
Claim · model-written summary
nolA-lacZ expression increased with population density.
- Taxon
- soybeanGlycine maxt0
- Gene
- nolA-lacZe0
- Outcome
- nolA-lacZ and nodD2-lacZ expressione0
- Direction
- increasede0
- Setting
- population densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nolA-lacZ and nodD2-lacZ expression increased with increasing population density.”
t0“soybean plants”
Claim · model-written summary
nodD2-lacZ expression increased with population density.
- Taxon
- soybeanGlycine maxt0
- Gene
- nodD2-lacZe0
- Outcome
- nodD2-lacZ expressione0
- Direction
- increasede0
- Setting
- population densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nolA-lacZ and nodD2-lacZ expression increased with increasing population density.”
t0“soybean plants”
Claim · model-written summary
Unlike wild type, the NolA mutant did not lose nodY-lacZ induction as density rose.
- Taxon
- soybeanGlycine maxt0
- Material
- NolA mutante0
- Gene
- nodY-lacZe0
- Outcome
- ability to induce nodY-lacZ expressione0
- Direction
- did not declinee0
- Comparator
- wild typee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Unlike the wild type, the ability to induce nodY-lacZ expression did not decline with population density in a NolA mutant.”
t0“soybean plants”
Claim · model-written summary
nodY-GUS expression in nodules was not repressed in the NolA mutant.
- Taxon
- soybeanGlycine maxt0
- Material
- NolA mutante0
- Gene
- nodY-GUSe0
- Outcome
- expression of a nodY-GUS fusione0
- Direction
- not repressede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression of a nodY-GUS fusion was not repressed in a NolA mutant”
t0“soybean plants”
Claim · model-written summary
Conditioned medium significantly reduced bacterial nod gene expression in culture.
- Taxon
- soybeanGlycine maxt0
- Treatment
- Addition of conditioned mediume0
- Gene
- nod genee0
- Outcome
- nod gene expressione0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Addition of conditioned medium to cultures significantly reduced nod gene expression.”
t0“soybean plants”
Claim · model-written summary
Conditioned medium treatment of inoculant cultures reduced bacterial soybean nodulation ability.
- Taxon
- soybean plantsGlycine maxe0
- Treatment
- Treatment of inoculant cultures with conditioned mediume0
- Interactor
- B. japonicumBradyrhizobium japonicume0symbiont
- Outcome
- ability of B. japonicum to nodulate soybean plantse0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment of inoculant cultures with conditioned medium also reduced the ability of B. japonicum to nodulate soybean plants.”
The same questions in other papers
inoculation · Bradyrhizobium japonicum · Glycine max (soybean)Results differ
21 papers in the same direction as this paper · 64 in the opposite direction
- positive
- positive
- positive
82 papers more in this group
See all 86 papers →in vitro · Bradyrhizobium japonicum · Glycine max (soybean)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
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.