Abstract
Cucumber (Cucumis sativus L.) damping-off, which is caused by the soilborne oomycete Pythium aphanidermatum, is an extremely damaging disease. An environmentally friendly and safe method of controlling damping-off in cucumber and other vegetable crops is biological control, which employs naturally existing antagonistic microorganisms. In this investigation, bacteria from root tissues (endophytic bacteria) and rhizosphere soil (rhizosphere bacteria) were isolated from Tamarix nilotica (Tamaricaceae), commonly known as salt cedar, and their potential to inhibit P. aphanidermatum and their efficacy in managing damping-off in cucumber under controlled glasshouse conditions were assessed. Ten rhizospheric and six endophytic bacteria with different morphological traits were isolated using nutrient agar medium. Of them, one endophytic bacterium (TaniEB3) and one rhizosphere bacterium (TaniRB10) showed strong inhibitory activity against P. aphanidermatum in in vitro tests and caused morphological defects in the pathogen's hyphae, as seen by scanning electron microscopy. These bacterial isolates were determined to be Sphingopyxis soli (TaniEB3) and Bacillus cereus (TaniRB10) based on MALDI-TOF-Biotyper analysis. In vitro compatibility analysis employing cross-streak assay revealed that S. soli TaniEB3 and B. cereus TaniRB10 were incompatible. B. cereus TaniRB10 and S. soli TaniEB3 exhibited NaCl tolerance up to 5% and 7.5%, respectively. In the two-sealed-base-plates tests, S. soli TaniEB3 was the only isolate to produce antimicrobial volatile chemicals that inhibited P. aphanidermatum's growth. Soil treatment with B. cereus TaniRB10 and S. soli TaniEB3 reduced the damping-off incidence in cucumber by 37.5% and 12.5%, respectively, compared to the P. aphanidermatum-infected control. As a biocontrol agent for managing P. aphanidermatum damping-off of cucumber, B. cereus TaniRB10 merits further investigation.
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Claims 9
Claim · model-written summary
Endophytic TaniEB3 and rhizosphere TaniRB10 showed strong in vitro inhibition of Pythium aphanidermatum.
- Taxon
- Cucumber
Cucumis sativust0 - Interactor
- P. aphanidermatumPythium aphanidermatume1pathogen
- Outcome
- strong inhibitory activitye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Damping-Off in Cucumber”
e1“one endophytic bacterium (TaniEB3) and one rhizosphere bacterium (TaniRB10) showed strong inhibitory activity against P. aphanidermatum in in vitro tests”
Claim · model-written summary
TaniRB10 and TaniEB3 caused morphological defects in P. aphanidermatum hyphae seen by scanning electron microscopy.
- Taxon
- CucumberCucumis sativust0
- Interactor
- P. aphanidermatumPythium aphanidermatume1pathogen
- Outcome
- morphological defectse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Damping-Off in Cucumber”
e1“one endophytic bacterium (TaniEB3) and one rhizosphere bacterium (TaniRB10) showed strong inhibitory activity against P. aphanidermatum in in vitro tests”
e2“caused morphological defects in the pathogen's hyphae, as seen by scanning electron microscopy”
Claim · model-written summary
Isolates S. soli TaniEB3 and B. cereus TaniRB10 were incompatible in the cross-streak assay.
- Taxon
- CucumberCucumis sativust0
- Outcome
- incompatiblee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Damping-Off in Cucumber”
e3“S. soli TaniEB3 and B. cereus TaniRB10 were incompatible”
Claim · model-written summary
B. cereus TaniRB10 tolerated NaCl up to 5%.
- Taxon
- CucumberCucumis sativust0
- Material
- B. cereus TaniRB10e4
- Outcome
- NaCl tolerancee4
- Value
- up to 5%e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Damping-Off in Cucumber”
e4“B. cereus TaniRB10 and S. soli TaniEB3 exhibited NaCl tolerance up to 5% and 7.5%, respectively”
Claim · model-written summary
S. soli TaniEB3 tolerated NaCl up to 7.5%.
- Taxon
- CucumberCucumis sativust0
- Material
- S. soli TaniEB3e4
- Outcome
- NaCl tolerancee4
- Value
- 7.5%e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Damping-Off in Cucumber”
e4“B. cereus TaniRB10 and S. soli TaniEB3 exhibited NaCl tolerance up to 5% and 7.5%, respectively”
Claim · model-written summary
S. soli TaniEB3 was the only isolate producing antimicrobial volatile chemicals that inhibited P. aphanidermatum growth.
- Taxon
- CucumberCucumis sativust0
- Material
- S. soli TaniEB3e5
- Interactor
- P. aphanidermatumPythium aphanidermatume5pathogen
- Compound
- antimicrobial volatile chemicalse5
- Outcome
- growthe5
- Direction
- inhibitede5
- Qualifier
- the only isolatee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Damping-Off in Cucumber”
e5“S. soli TaniEB3 was the only isolate to produce antimicrobial volatile chemicals that inhibited P. aphanidermatum's growth”
Claim · model-written summary
Soil treatment with B. cereus TaniRB10 reduced damping-off incidence in cucumber by 37.5% relative to the P. aphanidermatum-infected control.
- Taxon
- cucumberCucumis sativuse6
- Treatment
- Soil treatment with B. cereus TaniRB10e6
- Interactor
- P. aphanidermatumPythium aphanidermatume6pathogen
- Second interactor
- B. cereus TaniRB10
Bacillus cereuse6biocontrol_agent - Outcome
- damping-off incidencee6
- Direction
- reducede6
- Value
- 37.5%e6
- Comparator
- P. aphanidermatum-infected controle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Soil treatment with B. cereus TaniRB10 and S. soli TaniEB3 reduced the damping-off incidence in cucumber by 37.5% and 12.5%, respectively, compared to the P. aphanidermatum-infected control”
t0“Damping-Off in Cucumber”
Claim · model-written summary
Soil treatment with S. soli TaniEB3 reduced damping-off incidence in cucumber by 12.5% relative to the P. aphanidermatum-infected control.
- Taxon
- cucumberCucumis sativuse6
- Treatment
- S. soli TaniEB3e6
- Interactor
- P. aphanidermatumPythium aphanidermatume6pathogen
- Second interactor
- S. soli TaniEB3Sphingopyxis solie6biocontrol_agent
- Outcome
- damping-off incidencee6
- Direction
- reducede6
- Value
- 12.5%e6
- Comparator
- P. aphanidermatum-infected controle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Soil treatment with B. cereus TaniRB10 and S. soli TaniEB3 reduced the damping-off incidence in cucumber by 37.5% and 12.5%, respectively, compared to the P. aphanidermatum-infected control”
t0“Damping-Off in Cucumber”
Claim · model-written summary
The authors recommend further investigation of B. cereus TaniRB10 as a biocontrol agent against cucumber damping-off.
- Taxon
- cucumberCucumis sativuse7
- Outcome
- merits further investigatione7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“As a biocontrol agent for managing P. aphanidermatum damping-off of cucumber, B. cereus TaniRB10 merits further investigation”
t0“Damping-Off in Cucumber”