A natural co-obligate aphid endosymbiont consortium in the cedar aphid Cinara cedri, composed of Buchnera aphidicola BCc and Serratia symbiotica SCc. Genome-based metabolic inference shows that Buchnera BCc has lost some ancestral nutritional functions, while Serratia SCc retains or takes over functions needed by the host-associated consortium, including shared tryptophan biosynthesis and broader metabolic complementation.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Buchnera aphidicola BCc | NCBITaxon:372461 · TaxonMech · TraitMech |
CROSS_FEEDER
SYNTROPHIC_PARTNER
|
N/A |
|
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| Serratia symbiotica SCc — ontology label: Serratia symbiotica | NCBITaxon:138074 · TaxonMech · TraitMech |
CROSS_FEEDER
SYNTROPHIC_PARTNER
|
N/A |
|
|||
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.
Shared Tryptophan Biosynthesis
CROSS_FEEDINGCOMPUTATIONAL - genome reconstruction partitions tryptophan biosynthesis between Buchnera BCc trpEG, predicted to supply anthranilate, and Serratia SCc trpABCD, predicted to complete tryptophan synthesis. PARTIAL - inferred intermediate exchange is cross-feeding, not thermodynamic syntrophy or experimentally traced transport across the distinct bacteriocytes.
Source Taxon: Buchnera aphidicola BCc
Target Taxon: Serratia symbiotica SCc
Metabolites: L-tryptophan (CHEBI:16828 · MediaIngredientMech · CMMMech)
Biological Processes:
- tryptophan biosynthetic process (GO:0000162 · PathwayMech)
HYPOTHESIZED - partitioned tryptophan capacity could favor preservation of both partners by making complete nutrition depend on their complementary reactions. This is a source-proposed evolutionary mechanism, not a measured perturbation of consortium stability.
Evidence
-
doi:10.1371/journal.pgen.1002357 - PARTIAL (COMPUTATIONAL)"the biosynthesis of tryptophan is shared with the endosymbiont Serratia symbiotica SCc"
Serratia Takeover of Lost Buchnera Functions
CROSS_FEEDINGCOMPUTATIONAL - genome comparison indicates that Serratia SCc retains biosynthetic capacity absent from Buchnera BCc, including riboflavin provision in the inferred consortium. PARTIAL - nutritional complementation is proposed from gene content; synthesis capacity does not establish export of every product, transport route or reciprocal fitness magnitude.
Participating Taxa: Buchnera aphidicola BCc, Serratia symbiotica SCc
Metabolites: riboflavin (CHEBI:17015 · MediaIngredientMech · CMMMech)
HYPOTHESIZED - Serratia capacity complementing Buchnera losses could favor co-preservation of the two endosymbionts. Genomic reconstruction supports this interpretation without proving transport, partner necessity or a stability effect experimentally.
Evidence
-
doi:10.1371/journal.pgen.1002357 - PARTIAL (COMPUTATIONAL)"taken over by S. symbiotica"
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doi:10.1371/journal.pgen.1002357 - PARTIAL (COMPUTATIONAL)"not able to synthesize tryptophan and riboflavin"
Inferred Co-obligate Metabolic Complementation
HYPOTHESIZED - complementary metabolic losses and retained functions could favor co-preservation of Buchnera BCc and Serratia SCc in Cinara cedri. The source proposes a co-obligate evolutionary consortium; this is not an experimental persistence intervention, measured stability time course or thermodynamic syntrophy.
Participating Taxa: Buchnera aphidicola BCc, Serratia symbiotica SCc
Metabolites: L-tryptophan (CHEBI:16828 · MediaIngredientMech · CMMMech), riboflavin (CHEBI:17015 · MediaIngredientMech · CMMMech)
Evidence
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doi:10.1371/journal.pgen.1002357 - PARTIAL (COMPUTATIONAL)"metabolic complementation giving functional stability to the whole consortium"
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doi:10.1371/journal.pgen.1002357 - PARTIAL (COMPUTATIONAL)"both bacteria are evolving together towards the establishment of a powerful consortium"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
|
Buchnera aphidicola BCc genome project
NCBI BioProject for the Buchnera aphidicola BCc genome from Cinara cedri. |
GENOMICS | NCBI_BIOPROJECT | NCBI BioProject 16372 |
|
Serratia symbiotica SCc genome project
NCBI BioProject for Serratia symbiotica from Cinara cedri. |
GENOMICS | NCBI_BIOPROJECT | NCBI BioProject 32211 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Do resolved metabolite transport and partner perturbations validate nutritional co-dependence?
Retain the two explicit source-proposed co-preservation hypotheses rather than treating all component arrows as invalid. Host reactions were partly inferred from Acyrthosiphon pisum, not measured in Cinara cedri. Separate bacteriocytes require unresolved transport. Primary main text/tables/captions read, not images, supplements or reconstructed genomes. Cache-header PMCID mismatch and non-graph syntrophy/role wording remain #1268; the matching primary body was used, not an editorial cache summary.
Attaches to: ecological_interactions#Shared Tryptophan Biosynthesis, ecological_interactions#Serratia Takeover of Lost Buchnera Functions, ecological_interactions#Inferred Co-obligate Metabolic Complementation
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| aphid phloem-sap nutritional constraint | nutrient-deficient phloem diet | N/A |
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