A five-strain synthetic bacterial community (SynCom) assembled from endophytic bacteria isolated from multiple tissues of Pinus armandii to promote seedling growth and prime blister rust-associated defense responses. The optimized, functionally complementary SynCom comprises Pseudomonas koreensis RC1, Paenibacillus terrae RE7, Bacillus velezensis OB3 and NA3, and Bacillus subtilis NA11, selected for plant growth-promoting traits (nitrogen fixation, phosphate and potassium solubilization, IAA production) and antagonism of the rust pathogen. In pot experiments the SynCom increased seedling height and biomass and raised defense-related polyphenol oxidase and peroxidase activities relative to the control.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
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| Pseudomonas koreensis RC1 — ontology label: Pseudomonas koreensis | NCBITaxon:198620 · TaxonMech · TraitMech | N/A | |
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| Paenibacillus terrae RE7 — ontology label: Paenibacillus terrae | NCBITaxon:159743 · TaxonMech · TraitMech | N/A | |
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| Bacillus velezensis OB3 — ontology label: Bacillus velezensis | NCBITaxon:492670 · TaxonMech · TraitMech | N/A | |
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| Bacillus velezensis NA3 — ontology label: Bacillus velezensis | NCBITaxon:492670 · TaxonMech · TraitMech | N/A | |
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| Bacillus subtilis NA11 — ontology label: Bacillus subtilis | NCBITaxon:1423 · TaxonMech · TraitMech | N/A | |
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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.
Compatibility of Selected Endophytic Isolates
The five constituent strains were selected using pairwise compatibility tests. Public Supplement Figure S3 shows an agar/filter-disc assay with no inhibition zones among the tested strains. Preserve assay-specific compatibility, not demonstrated long-term stable coexistence, resource partitioning or a causal contribution of complementarity to seedling growth. Screened nitrogen-fixing/IAA traits do not establish ammonia or IAA exchange within this SynCom.
Participating Taxa: Pseudomonas koreensis RC1, Paenibacillus terrae RE7, Bacillus velezensis OB3, Bacillus velezensis NA3, Bacillus subtilis NA11
Evidence
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PMID:42322490 - SUPPORT (IN_VITRO)"Based on pairwise compatibility tests, a SynCom was constructed"
Antagonistic Activity of Selected Endophytic Isolates
Selected isolates showed antagonistic activity in vitro. Public Supplement Table S2 and Figure S1 identify Phomopsis sp. as the plate-inhibition target, distinct from the separate urediniospore-germination assay with cell-free fermentation supernatants (Figure S2). NA11, NA3 and RE7 occur among the tested inhibitory isolates and in the final SynCom; RC1 and OB3 are not among the nine spore-assay treatments. Preserve isolate inhibition without assigning every result to the complete five-strain community or asserting that direct pathogen inhibition caused host defense-enzyme induction.
Participating Taxa: Paenibacillus terrae RE7, Bacillus velezensis NA3, Bacillus subtilis NA11
Evidence
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PMID:42322490 - SUPPORT (IN_VITRO)"nine strains with significant antagonistic activity"
Pinus Seedling Growth Promotion
The optimized five-strain SynCom significantly increased Pinus armandii seedling height and biomass accumulation in pot experiments. Preserve this positive host-growth response. The accessible evidence does not isolate IAA production or nitrogen fixation as its mediator, demonstrate individual-strain necessity, or show reciprocal microbial fitness benefits.
Participating Taxa: Pseudomonas koreensis RC1, Paenibacillus terrae RE7, Bacillus velezensis OB3, Bacillus velezensis NA3, Bacillus subtilis NA11
Evidence
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PMID:42322490 - SUPPORT (IN_VIVO)"significantly increased seedling height and biomass accumulation."
Blister Rust-Associated Defense Enzyme Induction
SynCom treatment increased host polyphenol oxidase (PPO) and peroxidase (POD) activities by 19.1% and 157.3% relative to controls in the pot experiment. Preserve these positive defense-associated enzyme endpoints. They do not alone demonstrate priming, resistance to infection or disease control; the abstract explicitly calls for subsequent in planta biocontrol evaluation.
Participating Taxa: Pseudomonas koreensis RC1, Paenibacillus terrae RE7, Bacillus velezensis OB3, Bacillus velezensis NA3, Bacillus subtilis NA11
Biological Processes:
- defense response (GO:0006952 · PathwayMech)
Evidence
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PMID:42322490 - SUPPORT (IN_VIVO)"SynCom treatment enhanced defense-related enzyme activities, increasing polyphenol oxidase (PPO) and peroxidase (POD) activities by 19.1% and 157.3% relative to the control"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which strain functions mediate the observed seedling responses and actual blister-rust protection?
Preserve compatibility, isolate antagonism, growth and enzyme responses as separate positive findings. Public Supplement Figures S1-S3 and Table S2 separate Phomopsis inhibition, cell-free urediniospore inhibition and compatibility; these assays do not demonstrate stable community coexistence or direct inhibition by the complete SynCom. Both removed arrows conflated isolate selection/screening with causal mediation of host outcomes. No untested IAA/nitrogen exchange or reciprocal mutualism is assigned. Disease-challenge, strain-removal and mediator perturbations would resolve mechanisms. Main text remains inaccessible, while both public supplements were read and all six PDF pages visually inspected. Non-graph priming/stability and assay-scope claims remain #1709.
Attaches to: ecological_interactions#Compatibility of Selected Endophytic Isolates, ecological_interactions#Antagonistic Activity of Selected Endophytic Isolates, ecological_interactions#Pinus Seedling Growth Promotion, ecological_interactions#Blister Rust-Associated Defense Enzyme Induction
2 evidence item(s)
nine strains with significant antagonistic activity
Supports the positive isolate-screen result. Public supplements distinguish Phomopsis plates from the cell-free urediniospore assay and delimit which isolates overlap the final SynCom; not a whole-SynCom inhibition experiment.
SynCom treatment enhanced defense-related enzyme activities, increasing polyphenol oxidase (PPO) and peroxidase (POD) activities by 19.1% and 157.3% relative to the control
Supports the measured host enzyme increases, not demonstrated infection resistance or a specific isolate-mediated mechanism.
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