Abstract
Inoculation of wheat seedlings with Azospirillum brasilense Cd significantly increased the proton efflux of the roots 5 h after inoculation compared with noninoculated plants. Removal of the bacterial cells from the root surface 2, 4, or 10 h after inoculation did not affect proton extrusion, which remained similar to the proton efflux of inoculated roots with a permanent A. brasilense Cd population. Proton efflux from roots after short exposure to A. brasilense Cd was directly related to the inoculation level and to the physiological status of the bacterial cells. Active bacteria, at an optimal level for inoculation (10 5 –10 7 cfu∙mL −1 ), produced the most proton extrusion from roots. Stressed bacteria, i.e., bacteria exposed to starvation, 45 °C, anaerobic conditions, or a high level of streptomycin before inoculation, induced smaller but not statistically significant increases in proton efflux. Inoculation with dead A. brasilense Cd cells, cell-wall fragments, or several associative nonbeneficial rhizosphere bacteria belonging to other genera did not enhance the proton efflux compared with noninoculated plants. Continuous perfusion of the nutrient solution of plants while maintaining the bacterial cells in the root vicinity eliminated the proton efflux enhancement caused by A. brasilense Cd. Bacteria, regardless of species or stress conditions, in the absence of plants produced negligible proton efflux. It is suggested that short exposures of wheat roots to live A. brasilense Cd enhanced the proton efflux of roots, probably through the release of an as yet unidentified bacterial signal. Active metabolism of the bacterium is required for this enhancement, which is of a triggering nature. Key words: Azospirillum, beneficial bacteria, plant–bacteria interaction, proton efflux, rhizosphere bacteria, Triticum aestivum, wheat.
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Claims 11
Claim · model-written summary
Azospirillum inoculation significantly increased wheat-root proton efflux after five hours.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- Inoculation of wheat seedlings with Azospirillum brasilense Cde0
- Interactor
- Azospirillum brasilense Cd
Azospirillum brasilensee0symbiont - Outcome
- proton efflux of the rootse0
- Direction
- increasede0
- Qualifier
- 5 h after inoculatione0
- Comparator
- noninoculated plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inoculation of wheat seedlings with Azospirillum brasilense Cd significantly increased the proton efflux of the roots 5 h after inoculation compared with noninoculated plants”
Claim · model-written summary
Removing bacterial cells after short exposure did not change wheat-root proton extrusion relative to permanent inoculation.
- Treatment
- Removal of the bacterial cellse0
- Interactor
- A. brasilense CdAzospirillum brasilensee0symbiont
- Outcome
- proton extrusione0
- Direction
- did not affecte0
- Comparator
- inoculated roots with a permanent A. brasilense Cd populatione0
Not reportedTaxon
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Removal of the bacterial cells from the root surface 2, 4, or 10 h after inoculation did not affect proton extrusion, which remained similar to the proton efflux of inoculated roots with a permanent A. brasilense Cd population”
Claim · model-written summary
Root proton efflux increased with inoculation level.
- Treatment
- inoculation levele0
- Interactor
- A. brasilense CdAzospirillum brasilensee0symbiont
- Outcome
- Proton efflux from rootse0
Not reportedTaxonDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Proton efflux from roots after short exposure to A. brasilense Cd was directly related to the inoculation level and to the physiological status of the bacterial cells”
Claim · model-written summary
Root proton efflux was related to the physiological state of inoculated bacterial cells.
- Interactor
- A. brasilense CdAzospirillum brasilensee0symbiont
- Outcome
- Proton efflux from rootse0
- Qualifier
- physiological status of the bacterial cellse0
Not reportedTaxonDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Proton efflux from roots after short exposure to A. brasilense Cd was directly related to the inoculation level and to the physiological status of the bacterial cells”
Claim · model-written summary
Active bacteria at the optimal inoculation level produced the most root proton extrusion.
- Treatment
- Active bacteria, at an optimal level for inoculation (10 5 –10 7 cfu∙mL −1 )e0
- Outcome
- proton extrusion from rootse0
- Direction
- moste0
Not reportedTaxonComparator
Verbatim
e0“Active bacteria, at an optimal level for inoculation (10 5 –10 7 cfu∙mL −1 ), produced the most proton extrusion from roots”
Claim · model-written summary
Stressed bacteria produced smaller, nonsignificant increases in root proton efflux.
Not reportedTaxonComparator
Verbatim
e0“Stressed bacteria, i.e., bacteria exposed to starvation, 45 °C, anaerobic conditions, or a high level of streptomycin before inoculation, induced smaller but not statistically significant increases in proton efflux”
Claim · model-written summary
Dead bacterial cells did not enhance root proton efflux relative to noninoculated plants.
- Treatment
- dead A. brasilense Cd cellse0
- Interactor
- A. brasilense CdAzospirillum brasilensee0symbiont
- Outcome
- proton effluxe0
- Direction
- did not enhancee0
- Comparator
- noninoculated plantse0
Not reportedTaxon
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inoculation with dead A. brasilense Cd cells, cell-wall fragments, or several associative nonbeneficial rhizosphere bacteria belonging to other genera did not enhance the proton efflux compared with noninoculated plants”
Claim · model-written summary
Cell-wall fragments did not enhance root proton efflux.
- Treatment
- cell-wall fragmentse0
- Outcome
- proton effluxe0
- Direction
- did not enhancee0
- Comparator
- noninoculated plantse0
Not reportedTaxon
Verbatim
e0“Inoculation with dead A. brasilense Cd cells, cell-wall fragments, or several associative nonbeneficial rhizosphere bacteria belonging to other genera did not enhance the proton efflux compared with noninoculated plants”
Claim · model-written summary
Other nonbeneficial rhizosphere bacteria did not enhance root proton efflux.
- Treatment
- associative nonbeneficial rhizosphere bacteria belonging to other generae0
- Interactor
- rhizosphere bacteriae0other
- Outcome
- proton effluxe0
- Direction
- did not enhancee0
- Comparator
- noninoculated plantse0
Not reportedTaxon
Verbatim
e0“Inoculation with dead A. brasilense Cd cells, cell-wall fragments, or several associative nonbeneficial rhizosphere bacteria belonging to other genera did not enhance the proton efflux compared with noninoculated plants”
Claim · model-written summary
Continuous nutrient-solution perfusion removed the inoculation-related enhancement of root proton efflux.
- Treatment
- Continuous perfusion of the nutrient solutione0
- Interactor
- A. brasilense CdAzospirillum brasilensee0symbiont
- Outcome
- proton efflux enhancemente0
- Direction
- eliminatede0
Not reportedTaxonComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Continuous perfusion of the nutrient solution of plants while maintaining the bacterial cells in the root vicinity eliminated the proton efflux enhancement caused by A. brasilense Cd”
Claim · model-written summary
Bacteria alone produced negligible proton efflux.
Not reportedTaxon
Verbatim
e0“Bacteria, regardless of species or stress conditions, in the absence of plants produced negligible proton efflux”
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See all 105 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.