Abstract
The Bradyrhizobium sp. DOA9 strain isolated from a paddy field has the ability to nodulate a wide spectrum of legumes. Unlike other bradyrhizobia, this strain has a symbiotic plasmid harboring nod, nif and T3SS genes. This T3SS cluster contains all the genes necessary for the formation of the secretory apparatus and the transcriptional activator (TtsI), which is preceded by a nod-box motif. An in silico search predicted 14 effectors putatively translocated by this T3SS machinery. In this study, we explored the role of the T3SS in the symbiotic performance of DOA9 by evaluating the ability of a T3SS mutant (ΩrhcN) to nodulate legumes belonging to Dalbergioid, Millettioid and Genistoid tribes. Among the nine species tested, four (Arachis hypogea, Vigna radiata, Crotalaria juncea, Macroptilium atropurpureum) responded positively to the rhcN mutation (ranging from suppression of plant defense reactions, an increase in the number of nodules and a dramatic improvement in nodule development and infection), one (Stylosanthes hamata) responded negatively (fewer nodules and less nitrogen fixation) and four species (Aeschynomene americana, Aeschynomene afraspera, Indigofera tinctoria and Desmodium tortuosum) displayed no phenotype. We also tested the role of the T3SS in the ability of the DOA9 strain to endophytically colonize rice roots, but detected no effect of the T3SS mutation, in contrast to what was previously reported in the Bradyrhizobium SUTN9-2 strain. Taken together, these data indicate that DOA9 contains a functional T3SS that interferes with the ability of the strain to interact symbiotically with legumes but not with rice.
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Claims 5
Claim · model-written summary
Four legume species responded positively to rhcN mutation.
- Taxon
- Arachis hypogea, Vigna radiata, Crotalaria juncea, Macroptilium atropurpureume0
- Treatment
- rhcN mutatione0
- Interactor
- Bradyrhizobium sp. DOA9
Bradyrhizobium sp. DOA9t0symbiont - Outcome
- responded positivelye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“four (Arachis hypogea, Vigna radiata, Crotalaria juncea, Macroptilium atropurpureum) responded positively to the rhcN mutation”
t0“Bradyrhizobium sp. DOA9”
Claim · model-written summary
Stylosanthes hamata had fewer nodules with rhcN mutation.
- Taxon
- Stylosanthes hamata
_Taub._(6254148545).jpg?width=60)
Stylosanthes hamatae0 - Interactor
- Bradyrhizobium sp. DOA9Bradyrhizobium sp. DOA9t0symbiont
- Outcome
- nodulese0
- Direction
- fewere0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Taub._(6254148545).jpg?width=500)
Verbatim
e0“one (Stylosanthes hamata) responded negatively (fewer nodules and less nitrogen fixation)”
t0“Bradyrhizobium sp. DOA9”
Claim · model-written summary
Stylosanthes hamata had less nitrogen fixation with rhcN mutation.
- Taxon
- Stylosanthes hamataStylosanthes hamatae0
- Interactor
- Bradyrhizobium sp. DOA9Bradyrhizobium sp. DOA9t0symbiont
- Outcome
- nitrogen fixatione0
- Direction
- lesse0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“one (Stylosanthes hamata) responded negatively (fewer nodules and less nitrogen fixation)”
t0“Bradyrhizobium sp. DOA9”
Claim · model-written summary
Four legume species displayed no phenotype.
- Taxon
- Aeschynomene americana, Aeschynomene afraspera, Indigofera tinctoria and Desmodium tortuosum
Aeschynomene americana
Indigofera tinctoriaAeschynomene afraspera
Desmodium tortuosume0 - Interactor
- Bradyrhizobium sp. DOA9Bradyrhizobium sp. DOA9t0symbiont
- Outcome
- no phenotypee0
Not reportedTreatmentComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“four species (Aeschynomene americana, Aeschynomene afraspera, Indigofera tinctoria and Desmodium tortuosum) displayed no phenotype”
t0“Bradyrhizobium sp. DOA9”
Claim · model-written summary
T3SS mutation had no effect on rice root colonization.
- Taxon
- rice
Oryza sativae0 - Treatment
- T3SS mutatione0
- Interactor
- DOA9 straine0symbiont
- Outcome
- endophytically colonize rice rootse0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the ability of the DOA9 strain to endophytically colonize rice roots, but detected no effect of the T3SS mutation”
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