Abstract
Root colonization by certain non-pathogenic bacteria can induce systemic resistance to pathogen infections in plants. In a split-root assay with tomato plants, we investigated which determinants of the rhizobacterium Pseudomonas aeruginosa IE-6S+ were important for induction of resistance to the root-knot nematode Meloidogyne javanica. P. aeruginosa IE-6S+ produced 3.9±1.1 µg ml-1 salicylic acid (SA) in a liquid casamino acid medium under laboratory conditions. The bacterial inoculant induced resistance equivalent to the application of 10 mM synthetic SA. However, SA at this concentration did not produce significant mortality of M. javanica juveniles in vitro. Soil iron (2.4 mM FeCl3·6H2O) did not markedly alter the resistance that P. aeruginosa IE-6S+ induced in tomato roots, which suggested that P. aeruginosa IE-6S+ activity was not iron-regulated. However, the resistance reaction was greatly enhanced when IE-6S+ and SA were co-inoculated with 0.5% Tween-20. While IE-6S+ colonized the tomato rhizosphere at 6.38 log cfu per g fresh weight of root during the first 3 days after inoculation, the bacterial populations declined steadily, reaching a mean population density of 4.73 log cfu g-1 fresh weight of root at 21 days. The bacterium was not isolated from the unbacterized half of the split root system.
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Claims 7
Claim · model-written summary
P. aeruginosa IE-6S+ produced salicylic acid in liquid medium.
- Taxon
- tomato
Solanum lycopersicumt0 - Interactor
- P. aeruginosa IE-6S+
Pseudomonas aeruginosae0biocontrol_agent - Outcome
- P. aeruginosa IE-6S+ producede0
- Value
- 3.9±1.1 µg ml-1e0
- Setting
- laboratory conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“P. aeruginosa IE-6S+ produced 3.9±1.1 µg ml-1 salicylic acid (SA) in a liquid casamino acid medium under laboratory conditions.”
t0“Tomato”
Claim · model-written summary
The bacterial inoculant induced nematode resistance equivalent to 10 mM synthetic SA.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- bacterial inoculante0
- Outcome
- resistancee0
- Direction
- equivalente0
- Comparator
- application of 10 mM synthetic SAe0
Not reportedInteractor
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The bacterial inoculant induced resistance equivalent to the application of 10 mM synthetic SA.”
t0“Tomato”
Claim · model-written summary
Synthetic SA at 10 mM did not significantly kill M. javanica juveniles in vitro.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- SA at this concentratione0
- Interactor
- M. javanicaMeloidogyne javanicae0pathogen
- Outcome
- mortality of M. javanica juvenilese0
- Direction
- did not producee0
- Setting
- in vitroe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SA at this concentration did not produce significant mortality of M. javanica juveniles in vitro.”
t0“Tomato”
Claim · model-written summary
Soil iron did not markedly change bacterial induction of resistance in tomato roots.
- Taxon
- tomatoSolanum lycopersicume0
- Treatment
- Soil iron (2.4 mM FeCl3·6H2O)e0
- Interactor
- P. aeruginosa IE-6S+Pseudomonas aeruginosae0biocontrol_agent
- Outcome
- resistancee0
- Direction
- did not markedly altere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Soil iron (2.4 mM FeCl3·6H2O) did not markedly alter the resistance that P. aeruginosa IE-6S+ induced in tomato roots”
Claim · model-written summary
Co-inoculation with IE-6S+, SA and Tween-20 greatly enhanced resistance.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- IE-6S+ and SA were co-inoculated with 0.5% Tween-20e0
- Interactor
- IE-6S+e0biocontrol_agent
- Outcome
- resistance reactione0
- Direction
- greatly enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the resistance reaction was greatly enhanced when IE-6S+ and SA were co-inoculated with 0.5% Tween-20.”
t0“Tomato”
Claim · model-written summary
IE-6S+ rhizosphere populations declined from early colonization to day 21.
- Taxon
- tomatoSolanum lycopersicume0
- Interactor
- IE-6S+e0biocontrol_agent
- Outcome
- bacterial populationse0
- Direction
- declined steadilye0
- Value
- 4.73 log cfu g-1 fresh weight of roote0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“IE-6S+ colonized the tomato rhizosphere at 6.38 log cfu per g fresh weight of root during the first 3 days after inoculation, the bacterial populations declined steadily, reaching a mean population density of 4.73 log cfu g-1 fresh weight of root at 21 days.”
Claim · model-written summary
The bacterium was not recovered from the uninoculated half of the split root.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- not isolated from the unbacterized half of the split root systeme0
Not reportedInteractor
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The bacterium was not isolated from the unbacterized half of the split root system.”
t0“Tomato”
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