Abstract
Rhizobia live in the soil or enter into a nitrogen-fixing symbiosis with a suitable host plant. Each environment presents different challenges with respect to iron acquisition. The soybean symbiont Bradyrhizobium japonicum 61A152 can utilize a variety of siderophores (Fe[III]-specific ligands). Purification of iron-regulated outer membrane proteins had previously allowed the cloning of a gene, fegA, from B. japonicum 61A152, whose predicted protein shares significant amino acid similarity with known TonB-dependent siderophore receptors. Here, we show that fegA is in an operon with a gene, fegB, that is predicted to encode an inner membrane protein. Characterization of fegAB and fegB mutants shows that bothfegA and fegB are required for utilization of the siderophore ferrichrome. Whereas thefegB mutant forms a normal symbiosis, the fegAB mutant has a dramatic phenotype in planta. Six weeks after inoculation with a fegAB strain, soybean nodules do not contain leghemoglobin and do not fix nitrogen. Infected cells contain few symbiosomes and are filled with vesicles. As ferrichrome is a fungal siderophore not likely to be available in nodules, the symbiotic defect suggests that the fegAB operon is serving a different function in planta, possibly one involved in signaling between the two partners.
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Claims 7
Claim · model-written summary
fegA is in an operon with fegB.
- Taxon
- Soybean
Glycine maxt0 - Gene
- fegAe0
- Outcome
- fegA is in an operon with a gene, fegBe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“fegA is in an operon with a gene, fegB, that is predicted to encode an inner membrane protein.”
t0“Soybean”
Claim · model-written summary
Both fegA and fegB were required for ferrichrome utilization by the soybean symbiont.
- Taxon
- soybeanGlycine maxe1
- Interactor
- Bradyrhizobium japonicum 61A152
Bradyrhizobium japonicume1symbiont - Gene
- fegBe0
- Outcome
- utilization of the siderophore ferrichromee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“bothfegA and fegB are required for utilization of the siderophore ferrichrome.”
e1“soybean symbiont Bradyrhizobium japonicum 61A152”
Claim · model-written summary
The fegB mutant formed normal soybean symbiosis.
- Taxon
- soybeanGlycine maxt0
- Interactor
- fegB mutante0symbiont
- Gene
- fegBe0
- Outcome
- forms a normal symbiosise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“thefegB mutant forms a normal symbiosis”
t0“soybean”
Claim · model-written summary
Soybean nodules inoculated with the fegAB strain lacked leghemoglobin after six weeks.
- Taxon
- soybeanGlycine maxe0
- Organ / stage
- nodulese0
- Treatment
- inoculation with a fegAB straine0
- Interactor
- Bradyrhizobium japonicumBradyrhizobium japonicumt0symbiont
- Gene
- fegABe0
- Outcome
- do not contain leghemoglobine0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Six weeks after inoculation with a fegAB strain, soybean nodules do not contain leghemoglobin”
t0“Bradyrhizobium japonicum”
Claim · model-written summary
Soybean nodules inoculated with the fegAB strain did not fix nitrogen after six weeks.
- Taxon
- soybeanGlycine maxe0
- Organ / stage
- nodulese0
- Treatment
- inoculation with a fegAB straine0
- Interactor
- Bradyrhizobium japonicumBradyrhizobium japonicumt0symbiont
- Gene
- fegABe0
- Outcome
- do not fix nitrogene0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Six weeks after inoculation with a fegAB strain, soybean nodules do not contain leghemoglobin and do not fix nitrogen.”
t0“Bradyrhizobium japonicum”
Claim · model-written summary
Infected soybean cells contained few symbiosomes and were filled with vesicles.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- Infected cellse0
- Outcome
- few symbiosomes and are filled with vesiclese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Infected cells contain few symbiosomes and are filled with vesicles.”
t0“soybean”
Claim · model-written summary
The authors inferred that the fegAB operon may have another function in planta, possibly signaling.
- Taxon
- soybeanGlycine maxt0
- Gene
- fegABe0
- Outcome
- different function in plantae0
- Qualifier
- possibly one involved in signaling between the two partnerse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the symbiotic defect suggests that the fegAB operon is serving a different function in planta, possibly one involved in signaling between the two partners.”
t0“soybean”
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
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See all 86 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.