Abstract
The aim of this study was to understand whether competition for fatty acids in plant seed exudates by compost-derived seed-colonizing microbial communities could explain the suppression of plant infections initiated by sporangia of Pythium ultimum. The germination behavior of P. ultimum sporangia in response to cucumber seeds was measured to determine the impact of seed-colonizing microbes on pathogen suppression. Seed-colonizing microbial communities from municipal biosolids compost utilized cucumber seed exudates and linoleic acid in vitro, reducing the respective stimulatory activity of these elicitors to P. ultimum sporangial germination. However, when sporangia were observed directly in the spermosphere of seeds sown in the compost medium, levels of germination and sporangial emptying did not differ from the responses in sand. The percentage of aborted germ tubes was greater after incubating sporangia in compost medium for 12-h than the level of germ tube abortion when sporangia were incubated in sand. Abortion did not occur if previously germinated sporangia were supplemented with cucumber seed exudate. Furthermore, removal of cucumber seed exudate after various stages of germ tube emergence resulted in an increase in aborted germ tubes over time. Adding increasing levels of glucose directly to the compost medium alleviated germ tube abortion in the spermosphere and also eliminated disease suppression. These data fail to support a role for linoleic acid competition in Pythium seedling disease suppression but provide evidence for general carbon competition mediated by seed-colonizing microbial communities as a mechanism for the suppression of Pythium seed infections in municipal biosolids compost.
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Claims 8
Claim · model-written summary
Compost seed microbes consumed exudates and linoleic acid and reduced their stimulation of sporangial germination.
- Taxon
- cucumber
Cucumis sativuse0 - Interactor
- P. ultimumGlobisporangium ultimume0pathogen
- Second interactor
- Seed-colonizing microbial communitiese0biocontrol_agent
- Outcome
- P. ultimum sporangial germinatione0
- Direction
- reducinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seed-colonizing microbial communities from municipal biosolids compost utilized cucumber seed exudates and linoleic acid in vitro, reducing the respective stimulatory activity of these elicitors to P. ultimum sporangial germination.”
Claim · model-written summary
Sporangial germination and emptying in compost did not differ from sand.
- Taxon
- cucumberCucumis sativust0
- Outcome
- levels of germination and sporangial emptyinge0
- Direction
- did not differe0
- Comparator
- sande0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“levels of germination and sporangial emptying did not differ from the responses in sand.”
t0“The germination behavior of P. ultimum sporangia in response to cucumber seeds”
Claim · model-written summary
Compost increased aborted germ tubes relative to sand after 12 hours.
- Taxon
- cucumberCucumis sativust0
- Treatment
- compost medium for 12-he0
- Outcome
- percentage of aborted germ tubese0
- Direction
- greatere0
- Comparator
- sande0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The percentage of aborted germ tubes was greater after incubating sporangia in compost medium for 12-h than the level of germ tube abortion when sporangia were incubated in sand.”
t0“The germination behavior of P. ultimum sporangia in response to cucumber seeds”
Claim · model-written summary
Cucumber seed exudate prevented abortion of previously germinated sporangia.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- cucumber seed exudatee0
- Outcome
- Abortione0
- Direction
- did not occure0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Abortion did not occur if previously germinated sporangia were supplemented with cucumber seed exudate.”
Claim · model-written summary
Exudate removal increased aborted germ tubes over time.
- Taxon
- cucumberCucumis sativuse0
- Treatment
- removal of cucumber seed exudatee0
- Outcome
- aborted germ tubese0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“removal of cucumber seed exudate after various stages of germ tube emergence resulted in an increase in aborted germ tubes over time.”
Claim · model-written summary
Added glucose alleviated germ tube abortion.
- Taxon
- cucumberCucumis sativust0
- Treatment
- Adding increasing levels of glucosee0
- Outcome
- germ tube abortione0
- Direction
- alleviatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Adding increasing levels of glucose directly to the compost medium alleviated germ tube abortion in the spermosphere”
t0“The germination behavior of P. ultimum sporangia in response to cucumber seeds”
Claim · model-written summary
Added glucose eliminated disease suppression.
- Taxon
- cucumberCucumis sativust0
- Treatment
- glucosee0
- Outcome
- disease suppressione0
- Direction
- eliminatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Adding increasing levels of glucose directly to the compost medium alleviated germ tube abortion in the spermosphere and also eliminated disease suppression.”
t0“The germination behavior of P. ultimum sporangia in response to cucumber seeds”
Claim · model-written summary
The results favor general carbon competition over linoleic acid competition as the suppression mechanism.
- Taxon
- cucumberCucumis sativust0
- Outcome
- suppression of Pythium seed infectionse0
- Qualifier
- general carbon competition mediated by seed-colonizing microbial communitiese0
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PythiumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“These data fail to support a role for linoleic acid competition in Pythium seedling disease suppression but provide evidence for general carbon competition mediated by seed-colonizing microbial communities as a mechanism for the suppression of Pythium seed infections in municipal biosolids compost.”
t0“The germination behavior of P. ultimum sporangia in response to cucumber seeds”
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