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Arabidopsis Coumarin Root SynCom

Community ID CommunityMech:000094
Ecological State ENGINEERED
Environment rhizosphere
ENVO:00005801 · HabitatMech ↗

A hydroponic 22-member Arabidopsis root-isolate SynCom used to detect strain-level rhizosphere community shifts caused by phytoalexin, flavonoid, and coumarin exudates. Under iron deficiency, F6'H1-dependent catecholic coumarins suppress the coumarin-sensitive isolate Pseudomonas sp. Root329 through a peroxide-linked mechanism that contributes to the overall wild-type-like community profile.

Taxonomy

Taxon Ontology ID Functional Roles Abundance
Arabidopsis root-isolated bacteria — ontology label: Bacteria NCBITaxon:2 · TaxonMech · TraitMech N/A
  • PMID:31152139 - SUPPORT (IN_VITRO)
    "We employed a reduced synthetic community (SynCom) of Arabidopsis thaliana root-isolated bacteria to detect community shifts that occur in the absence of the secreted small-molecule phytoalexins, flavonoids, and coumarins."
Pseudomonas sp. Root329 — ontology label: Pseudomonas NCBITaxon:286 · TaxonMech · TraitMech N/A
  • PMID:31152139 - SUPPORT (IN_VITRO)
    "Pseudomonas sp. Root329 was found to consistently respond positively to lines that lack biosynthesis and release of oxidized coumarins"

Ecological Interactions

The graph shows only explicitly linked interaction participants. Community members without an asserted participant link are omitted; membership alone does not imply an interaction.

Ecological interaction network for Arabidopsis Coumarin Root SynCom Bipartite graph where circles represent taxa and non-circular symbols represent interactions. Rare or untyped interactions share the Other symbol; exact curated types remain in the interaction details.
Taxon
Other

Iron-Limited Catecholic Coumarin Exudation

Iron-deficient Arabidopsis roots exude the catecholic coumarins sideretin, fraxetin and esculetin. Biosynthesis/release mutants alter the root community, but exudation is not itself evidence of reciprocal competition.

Metabolites: coumarins (CHEBI:23403 · MediaIngredientMech · CMMMech), iron(3+) (CHEBI:29034 · MediaIngredientMech · CMMMech)

Downstream Effects:
→ Catecholic Coumarin Peroxide Generation

The exuded catecholic compounds supply the chemical species shown separately to generate peroxide in iron-deficient MS medium; this connection does not measure peroxide concentration at the colonized root.

Evidence

  • PMID:31152139 - SUPPORT (IN_VIVO)
    "Sideretin, fraxetin, and esculetin are confirmed major coumarins exuded by wild-type roots under iron deficiency"

Catecholic Coumarin Peroxide Generation

Purified sideretin, fraxetin and esculetin generated hydrogen peroxide in iron-deficient MS medium over 24 hours. This is cell-free redox chemistry; the separate nutrient-agar inhibition and catalase-rescue assays test a bacterial consequence.

Metabolites: coumarins (CHEBI:23403 · MediaIngredientMech · CMMMech), iron(3+) (CHEBI:29034 · MediaIngredientMech · CMMMech), hydrogen peroxide (CHEBI:16240 · MediaIngredientMech · CMMMech)

Downstream Effects:
→ Pseudomonas Root329 Coumarin Sensitivity

PARTIAL - peroxide generation and abolition of sideretin inhibition by catalase support peroxide involvement in Root329 sensitivity. Chemistry in iron-deficient MS and inhibition on nutrient agar are separate assays, not a direct root-community peroxide measurement.

Evidence

  • PMID:31152139 - SUPPORT (IN_VITRO)
    "Hydrogen peroxide was generated by the catecholic coumarins sideretin, fraxetin, and esculetin in iron-deficient Murashige and Skoog media over a 24-h period"

Pseudomonas Root329 Coumarin Sensitivity

Purified sideretin strongly inhibited Pseudomonas Root329 on nutrient agar, while fraxetin had a weaker effect. Catalase and soluble iron relieved sideretin inhibition. Sensitivity differed among tested pseudomonads, so this is not a genus-wide susceptibility claim.

Participating Taxa: Pseudomonas sp. Root329

Metabolites: coumarins (CHEBI:23403 · MediaIngredientMech · CMMMech), hydrogen peroxide (CHEBI:16240 · MediaIngredientMech · CMMMech)

Biological Processes:

Downstream Effects:
→ Pseudomonas-Weighted Coumarin Community Shift

PARTIAL - Root329's compound sensitivity is a candidate explanation for its root relative-abundance response to coumarin biosynthesis and supplementation. The experiments do not isolate peroxide as the mediator within the intact root community or establish absolute depletion.

Evidence

  • PMID:31152139 - SUPPORT (IN_VITRO)
    "severe growth inhibition of Pseudomonas sp. Root329 by the predominant wild-type coumarin sideretin, and moderate inhibition by fraxetin"
  • PMID:31152139 - SUPPORT (IN_VITRO)
    "inhibitory activity of sideretin on Pseudomonas sp. Root329 could be abolished with addition of catalase"

Pseudomonas-Weighted Coumarin Community Shift

Root329 relative abundance increased in f6'h1 roots and declined after coumarin supplementation, with partial restoration of the community profile. In-silico removal/rescaling of Root329 reduced the profile difference; this was not a physical Root329 dropout. Separate reduced-community experiments retained the response. Supplied scopoletin can be converted by the plant, so complementation does not imply identical direct antimicrobial activity for every added compound.

Participating Taxa: Pseudomonas sp. Root329

Metabolites: coumarins (CHEBI:23403 · MediaIngredientMech · CMMMech)

Evidence

  • PMID:31152139 - SUPPORT (IN_VIVO)
    "Pseudomonas sp. Root329 became less abundant at the f6 ′ h1 root with the addition of either coumarin"
  • PMID:31152139 - SUPPORT (COMPUTATIONAL)
    "Removing Pseudomonas sp. Root329 by in silico rescaling substantially diminished the community profile shift between wild type and f6 ′ h1"

Knowledge gaps & discussions (1)

KNOWLEDGE_GAP OPEN Does root-local peroxide mediate absolute Root329 suppression under native conditions?

PMID:31152139 distinguishes cell-free chemistry, nutrient-agar catalase rescue, plant complementation and computational rescaling. Their combination supports a mechanism but does not isolate peroxide mediation at the root. Absolute abundances, strain-specific susceptibility and transfer beyond the controlled plant system remain unresolved.

Attaches to: ecological_interactions#Iron-Limited Catecholic Coumarin Exudation, ecological_interactions#Catecholic Coumarin Peroxide Generation, ecological_interactions#Pseudomonas Root329 Coumarin Sensitivity, ecological_interactions#Pseudomonas-Weighted Coumarin Community Shift

Environmental Factors

Factor Value Unit
defined synthetic community design 22-member synthetic community of Arabidopsis thaliana root endophyte isolates. N/A
  • PMID:31152139 - SUPPORT (IN_VITRO)
    "We employed a reduced synthetic community (SynCom) of Arabidopsis thaliana root-isolated bacteria to detect community shifts that occur in the absence of the secreted small-molecule phytoalexins, flavonoids, and coumarins."
iron-deficient Murashige and Skoog medium iron-deficient hydroponic medium N/A
  • PMID:31152139 - SUPPORT (IN_VITRO)
    "lack of coumarin biosynthesis in f6'h1 mutant plant lines causes a shift in the root microbial community specifically under iron deficiency"

Growth Media

quarter-strength tryptic soy broth (root-isolate SynCom inoculum); hydroponic Murashige and Skoog medium for the Arabidopsis host

Preparation notes: SynCom strains were grown to saturation in quarter-strength tryptic soy broth and washed with phosphate-buffered saline before root inoculation; the Arabidopsis host was grown hydroponically, with the medium around 13-day-old seedlings inoculated with the SynCom and the root community profiled at 20 days; iron-deficient Murashige and Skoog media were used to test the coumarin-dependent community shift.

Evidence

PMID:31152139

"All SynCom strains were grown to saturation in quarter-strength tryptic soy broth and washed with phosphate-buffered saline before root inoculation."

PMID:31152139

"The media surrounding hydroponically grown 13-d-old A. thaliana seedlings was inoculated with a 22-member SynCom"

Cross-Mech Suite Links

Explore related entities across the CultureBotAI X-Mech knowledge bases:

HabitatMech: rhizosphere ↗ TaxonMech: Arabidopsis root-isolated bacteria ↗ TraitMech: Arabidopsis root-isolated bacteria ↗ TaxonMech: Pseudomonas sp. Root329 ↗ TraitMech: Pseudomonas sp. Root329 ↗ CultureMech Growth Media ↗ PathwayMech Pathways ↗