Abstract
Cluster roots of white lupin are induced by low phosphorus (LP) to efficiently access unavailable P, but how soilborne microbes are associated with cluster root formation (CRF) is unclear. We investigated the roles of soilborne bacteria in CRF response to LP by high-throughput sequencing and root-bacteria interactions. Cluster root number was significantly decreased in plants grown in sterilized soil compared with nonsterilized soil. Proteobacteria was enriched in CR, as shown by microbiome analysis of soil (bulk, rhizosphere, and rhizosheath) and roots (main, lateral, and CR). Large-scale gene expression level implicated ethylene mediation in CRF. Klebsiella pneumoniae (P7), a soilborne bacterium belonging to Proteobacteria, was isolated from CR. Among 11 isolated strains, P7 exhibited the highest 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activity; this enzyme inhibits the biosynthesis of ethylene in plants by the cleavage of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and promotes CRF under LP. We constructed an ACCD-deficit mutant accd in the P7 genetic background. The loss-of-function mutation failed to promote CRF under LP conditions. Also, auxin responses may be involved in K. pneumoniae-ethylene-mediated CRF. Overall, we propose that the soilborne bacterium K. pneumoniae promotes CRF of white lupin in response to LP by ethylene mediation.
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Claims 8
Claim · model-written summary
Sterilized soil decreased white lupin cluster root number relative to nonsterilized soil.
Verbatim
e0“Cluster root number was significantly decreased in plants grown in sterilized soil compared with nonsterilized soil.”
t0“white lupin”
Claim · model-written summary
Proteobacteria was enriched in cluster roots.
- Taxon
- ProteobacteriaPseudomonadotae0
- Interactor
- white lupint0host
- Outcome
- enriched in CRe0
- Direction
- enrichede0
Verbatim
e0“Proteobacteria was enriched in CR, as shown by microbiome analysis of soil (bulk, rhizosphere, and rhizosheath) and roots (main, lateral, and CR).”
t0“white lupin”
Claim · model-written summary
Gene expression implicated ethylene mediation in cluster root formation.
Verbatim
e0“Large-scale gene expression level implicated ethylene mediation in CRF.”
t0“white lupin”
Claim · model-written summary
Klebsiella pneumoniae P7 was isolated from cluster roots.
- Taxon
- Klebsiella pneumoniae
Klebsiella pneumoniaee0 - Material
- P7e0
- Interactor
- white lupint0host
- Outcome
- isolated from CRe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Klebsiella pneumoniae (P7), a soilborne bacterium belonging to Proteobacteria, was isolated from CR.”
t0“white lupin”
Claim · model-written summary
P7 had the highest ACC deaminase activity among eleven strains.
- Taxon
- Klebsiella pneumoniaeKlebsiella pneumoniaee1
- Material
- P7e0
- Outcome
- 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activitye0
- Direction
- higheste0
- Comparator
- 11 isolated strainse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Among 11 isolated strains, P7 exhibited the highest 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activity”
e1“Klebsiella pneumoniae (P7), a soilborne bacterium belonging to Proteobacteria, was isolated from CR.”
Claim · model-written summary
ACCD inhibits plant ethylene biosynthesis by cleaving its precursor and promotes cluster root formation under low phosphorus.
Verbatim
e0“this enzyme inhibits the biosynthesis of ethylene in plants by the cleavage of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and promotes CRF under LP.”
t0“white lupin”
Claim · model-written summary
The ACCD loss-of-function mutant failed to promote cluster root formation under low phosphorus.
- Taxon
- white lupint0
- Treatment
- loss-of-function mutatione0
- Outcome
- CRFe0
- Direction
- failed to promotee0
- Qualifier
- under LP conditionse0
Not reportedComparator
Verbatim
e0“We constructed an ACCD-deficit mutant accd in the P7 genetic background. The loss-of-function mutation failed to promote CRF under LP conditions.”
t0“white lupin”
Claim · model-written summary
Auxin responses may contribute to K. pneumoniae-ethylene-mediated cluster root formation.
- Taxon
- white lupint0
- Interactor
- K. pneumoniaeKlebsiella pneumoniaee0other
- Compound
- auxine0
- Outcome
- CRFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Also, auxin responses may be involved in K. pneumoniae-ethylene-mediated CRF.”
t0“white lupin”