Abstract
We have been using a mutational approach to determine how plant-beneficial bacteria such as Enterobacter cloacae 501R3 obtain carbon and energy for colonization of subterranean portions of cucumber and other plants. Reduced carbon detected in cucumber root exudate consisted of 73.3 % amino acids, 22.2 % organic acids and 4.4 % carbohydrate. Ent. cloacae M2, a mini-Tn5 Km transposon mutant of strain 501R3, was severely reduced in in vitro growth relative to strain 501R3 on the mixture of amino acids and organic acids detected in cucumber root exudate when these compounds were supplied as the sole source of carbon and energy, but was similar in growth on the mixture of carbohydrates detected in this exudate. Molecular and biochemical characterization of Ent. cloacae M2 indicated that the transposon was inserted in sdhA, which encodes a subunit of succinate dehydrogenase. Ent. cloacae A-11, a mutant of strain 501R3 with a mini-Tn5 Km insertion in pfkA, was severely reduced in in vitro growth relative to strain 501R3 on the mixture of carbohydrates detected in cucumber root exudate, but similar in growth on the mixture of amino acids and organic acids. When strains A-11 and M2 were coapplied with strain 501R3 to cucumber seeds above carrying capacity in competitive root colonization assays, populations of strains A-11 and M2 were roughly one order of magnitude lower than those of strain 501R3 in cucumber rhizosphere, while populations of strains A-11 and M2 were similar to one other when coapplied to cucumber seeds. When Ent. cloacae strains were coapplied to cucumber seeds below carrying capacity, populations of A-11 and M2 were roughly two to three orders of magnitude lower than those of 501R3 in cucumber rhizosphere, and populations of A-11 were significantly lower than those of M2 when these two strains were coapplied to cucumber seed. The experiments reported here indicate an important role for pfkA and sdhA and the catabolism of carbohydrates, and of amino acids and organic acids, respectively, in the colonization of cucumber roots by Ent. cloacae. The results reported here also indicate that catabolism of carbohydrates by this bacterium is more important than catabolism of amino acids and organic acids at lower population densities, despite the much higher relative quantities of amino acids and organic acids detected in cucumber root exudate.
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Claims 13
Claim · model-written summary
Reduced carbon in cucumber root exudate was 73.3 % amino acids.
- Taxon
- cucumber
Cucumis sativuse0 - Organ / stage
- root exudatee0
- Outcome
- Reduced carbon detected in cucumber root exudatee0
- Value
- 73.3 %e0
- Qualifier
- amino acidse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduced carbon detected in cucumber root exudate consisted of 73.3 % amino acids, 22.2 % organic acids and 4.4 % carbohydrate”
Claim · model-written summary
Reduced carbon in cucumber root exudate was 22.2 % organic acids.
- Taxon
- cucumberCucumis sativuse0
- Organ / stage
- root exudatee0
- Outcome
- Reduced carbon detected in cucumber root exudatee0
- Value
- 22.2 %e0
- Qualifier
- organic acidse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduced carbon detected in cucumber root exudate consisted of 73.3 % amino acids, 22.2 % organic acids and 4.4 % carbohydrate”
Claim · model-written summary
Reduced carbon in cucumber root exudate was 4.4 % carbohydrate.
- Taxon
- cucumberCucumis sativuse0
- Organ / stage
- root exudatee0
- Outcome
- Reduced carbon detected in cucumber root exudatee0
- Value
- 4.4 %e0
- Qualifier
- carbohydratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduced carbon detected in cucumber root exudate consisted of 73.3 % amino acids, 22.2 % organic acids and 4.4 % carbohydrate”
Claim · model-written summary
Mutant M2 growth in vitro was severely reduced relative to strain 501R3 on the amino acid and organic acid mixture.
- Taxon
- cucumberCucumis sativuse0
- Material
- mini-Tn5 Km transposon mutante0
- Treatment
- mixture of amino acids and organic acidse0
- Interactor
- Ent. cloacae M2e0symbiont
- Outcome
- in vitro growthe0
- Direction
- severely reducede0
- Comparator
- strain 501R3e0
- Setting
- in vitroe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ent. cloacae M2, a mini-Tn5 Km transposon mutant of strain 501R3, was severely reduced in in vitro growth relative to strain 501R3 on the mixture of amino acids and organic acids detected in cucumber root exudate when these compounds were supplied as the sole source of carbon and energy”
Claim · model-written summary
Mutant M2 growth in vitro was similar to strain 501R3 on the carbohydrate mixture.
- Taxon
- cucumberCucumis sativuse0
- Material
- mini-Tn5 Km transposon mutante0
- Treatment
- mixture of carbohydratese1
- Interactor
- Ent. cloacae M2e0symbiont
- Outcome
- in vitro growthe0
- Direction
- no_changeinferrede0
- Comparator
- strain 501R3e0
- Setting
- in vitroe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ent. cloacae M2, a mini-Tn5 Km transposon mutant of strain 501R3, was severely reduced in in vitro growth relative to strain 501R3 on the mixture of amino acids and organic acids detected in cucumber root exudate when these compounds were supplied as the sole source of carbon and energy”
e1“but was similar in growth on the mixture of carbohydrates detected in this exudate”
Claim · model-written summary
The transposon in Ent. cloacae M2 was inserted in sdhA, which encodes a succinate dehydrogenase subunit.
- Taxon
- cucumberCucumis sativuse0
- Material
- Ent. cloacae M2e1
- Interactor
- Ent. cloacae M2e1symbiont
- Gene
- sdhAe1
- Outcome
- the transposon was inserted in sdhAe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“colonization of subterranean portions of cucumber”
e1“Molecular and biochemical characterization of Ent. cloacae M2 indicated that the transposon was inserted in sdhA, which encodes a subunit of succinate dehydrogenase”
Claim · model-written summary
Ent. cloacae A-11 (pfkA insertion) growth in vitro was severely reduced relative to strain 501R3 on the carbohydrate mixture.
- Taxon
- cucumberCucumis sativuse0
- Material
- Ent. cloacae A-11e0
- Treatment
- mixture of carbohydratese0
- Interactor
- Ent. cloacae A-11e0symbiont
- Gene
- pfkAe0
- Outcome
- in vitro growthe0
- Direction
- severely reducede0
- Comparator
- strain 501R3e0
- Setting
- in vitroe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ent. cloacae A-11, a mutant of strain 501R3 with a mini-Tn5 Km insertion in pfkA, was severely reduced in in vitro growth relative to strain 501R3 on the mixture of carbohydrates detected in cucumber root exudate, but similar in growth on the mixture of amino acids and organic acids”
Claim · model-written summary
Ent. cloacae A-11 growth in vitro was similar to strain 501R3 on the amino acid and organic acid mixture.
- Taxon
- cucumberCucumis sativuse0
- Material
- Ent. cloacae A-11e0
- Treatment
- mixture of amino acids and organic acidse0
- Interactor
- Ent. cloacae A-11e0symbiont
- Gene
- pfkAe0
- Outcome
- in vitro growthe0
- Direction
- no_changeinferrede0
- Comparator
- strain 501R3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ent. cloacae A-11, a mutant of strain 501R3 with a mini-Tn5 Km insertion in pfkA, was severely reduced in in vitro growth relative to strain 501R3 on the mixture of carbohydrates detected in cucumber root exudate, but similar in growth on the mixture of amino acids and organic acids”
Claim · model-written summary
Above carrying capacity, A-11 and M2 populations in cucumber rhizosphere were about one order of magnitude lower than strain 501R3.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- coapplied with strain 501R3 to cucumber seeds above carrying capacitye0
- Interactor
- strains A-11 and M2e0symbiont
- Outcome
- populations of strains A-11 and M2e0
- Direction
- lowere0
- Value
- one order of magnitudee0
- Comparator
- strain 501R3e0
- Setting
- cucumber rhizospheree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When strains A-11 and M2 were coapplied with strain 501R3 to cucumber seeds above carrying capacity in competitive root colonization assays, populations of strains A-11 and M2 were roughly one order of magnitude lower than those of strain 501R3 in cucumber rhizosphere”
Claim · model-written summary
Above carrying capacity, A-11 and M2 populations were similar to each other when coapplied to cucumber seeds.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- coapplied to cucumber seedse0
- Interactor
- strains A-11 and M2e0symbiont
- Outcome
- populations of strains A-11 and M2e0
- Direction
- no_changeinferrede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“populations of strains A-11 and M2 were similar to one other when coapplied to cucumber seeds”
Claim · model-written summary
Below carrying capacity, A-11 and M2 populations in cucumber rhizosphere were two to three orders of magnitude lower than strain 501R3.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- coapplied to cucumber seeds below carrying capacitye0
- Interactor
- A-11 and M2e0symbiont
- Outcome
- populations of A-11 and M2e0
- Direction
- lowere0
- Value
- two to three orders of magnitudee0
- Comparator
- 501R3e0
- Setting
- cucumber rhizospheree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When Ent. cloacae strains were coapplied to cucumber seeds below carrying capacity, populations of A-11 and M2 were roughly two to three orders of magnitude lower than those of 501R3 in cucumber rhizosphere”
Claim · model-written summary
Below carrying capacity, A-11 populations were significantly lower than M2 populations.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- coapplied to cucumber seede0
- Interactor
- A-11e0symbiont
- Second interactor
- M2e0symbiont
- Outcome
- populations of A-11e0
- Direction
- significantly lowere0
- Comparator
- M2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“populations of A-11 were significantly lower than those of M2 when these two strains were coapplied to cucumber seed”
Claim · model-written summary
Carbohydrate catabolism by this bacterium is more important than amino acid and organic acid catabolism at lower population densities.
- Taxon
- cucumberCucumis sativuse0
- Outcome
- more importante1
- Qualifier
- catabolism of carbohydrates by this bacterium is more important than catabolism of amino acids and organic acids at lower population densitiese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“colonization of subterranean portions of cucumber”
e1“catabolism of carbohydrates by this bacterium is more important than catabolism of amino acids and organic acids at lower population densities”