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fungal rhizomorph formation

traitmech:000662 · CLASS · PROPOSED

A morphological phenotype in which a fungus forms root-like, multihyphal structures through coordinated hyphal growth.

Trait evidence (4)

  • DOI:10.1016/j.fgb.2009.04.005
    Rhizomorphs of wood-decay basidiomycetes are root-like structures produced by the coordinated growth of thousands of hyphae.

    Yafetto, Davis and Money (2009), PMID:19427390; scientific abstract retrieved directly through Europe PMC. The naming sentence supports the formation phenotype, not a universal hyphal-count threshold. Armillaria gallica cultures were tested in media of different gel strengths. The reported 760 kPa is an osmolality-derived turgor estimate, whereas 40-300 kPa describes pressure corresponding to measured tip forces. These are distinct readouts, not trait thresholds. Full text, figures, supplements and isolate provenance were not inspected; no canonical example is inferred from this abstract.

  • DOI:10.1016/j.mycres.2005.09.006
    Air pores develop near the inoculum plug shortly after inoculation, arising directly from the mycelium, and rhizomorphs are initiated from them.

    Pareek, Allaway and Ashford (2006), PMID:16376531; scientific abstract checked against the directly retrieved PDF and Europe PMC abstract. Methods, Results, Discussion, Table 1 and actual Figures 9-17 were inspected. Results place first tips on day 6, but Table 1 reports tips on day 5; no exact onset is asserted. Table 1 counts tips and air pores on five plates, not organisms. The main oxygen-conductance assay used cut rhizomorph ends; it does not establish intact-rind permeability or universal oxygen adaptation. Air pores and rhizomorphs are distinct structures. Remaining figure images and supplements were not inspected.

  • DOI:10.1186/s12862-017-0877-3
    All armillarioid species have the capacity to form rhizomorphs in culture, but only the later diverging lineages have been observed to form them in nature

    Koch et al. (2017), PMID:28122504, PMC5264464; directly retrieved full-text XML, Discussion subsection The rise of rhizomorphs and Table 2. The quoted clause precedes a parenthetical figure/table citation. This is the authors' comparative summary, partly based on earlier literature, not a new formation experiment on every species. They explicitly describe unmelanized rhizomorphs in culture. Field non-observation is not biological absence; the summary does not establish expression in every strain or condition. Full Methods, actual figures, supplements and additional isolate provenance were not inspected.

  • DOI:10.3114/fuse.2024.14.03
    Many rhizomorph-forming fungi occur in the litter on the forest floor (ground species), while other species make aerial rhizomorph networks (epiphytic species).

    Oliveira et al. (2024), PMID:39830290, PMC11739697; Introduction read directly in PMC HTML after the Europe PMC XML endpoint failed. This terminology passage supports not restricting formation to underground growth. These authors adopt a narrow melanized, differentiated, organized-tip concept and contrast Singer's white rhizomorph usage with mycelial cords. That is their attributed account; the original Singer/Rayner sources were not retrieved. Abstract, Introduction and selected taxonomic text/captions were read, but actual figures, supplements and the full Methods were not inspected. No additional canonical taxon or exact cord synonym is asserted.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1016/j.fgb.2009.04.005

Parent traits (1)

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Canonical examples (1)

Organisms cited as exemplars of this trait. Taxon ids are NCBITaxon and link out to the NCBI record.

  • Armillaria luteobubalina NCBITaxon:153913 DOI:10.1016/j.mycres.2005.09.006 Isolate 930199KGS in Pareek et al. (2006), Fungal material and culture conditions, Results and Figures 9-17. Primary Methods at https://doi.org/10.1016/j.mycres.2005.09.006 identify the University of Western Sydney collection culture as originating from fruit bodies collected at Gore Hill Park, North Sydney, in June 1993. Rhizomorph development was observed on malt-marmite agar in darkness at 23 C. The Methods provenance and actual images were inspected; natural origin is not inferred from a wild-type label. NCBI Taxonomy confirms the species ID, label and rank. This is a qualified culture observation, not evidence for every strain or condition.

Discussions and Knowledge Gaps (2)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Resolve rhizomorph/cord terminology and a closer fungal parent.

CURATION TODO OPEN fungal-rhizomorph-scope-and-hierarchy · raised by codex · 2026-10-07

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

Use phenotype METPO:1000059. Mycelial growth traitmech:000074 is explicitly bacterial; filament shaped METPO:1000674 is a cell-shape class; rhizoid colony METPO:1007068 and filamentous colony METPO:1007066 concern colony outlines. None is an exact fungal multihyphal formation record. Hyphal anastomosis traitmech:000605 denotes fusion and fungal sclerotium formation traitmech:000660 denotes compact resting bodies. Koch et al. (2017) use rhizomorph for unmelanized culture structures, whereas Oliveira et al. (2024) adopt the narrower melanized, organized-tip sense and distinguish mycelial cords. The broad formation definition does not settle that anatomical boundary: retain the source attribution and do not assert exact cord/strand synonyms, a universal pigment requirement or an underground-only habitat. A closer fungal growth-form parent and external equivalences require upstream review; no xrefs or SSSOM mappings are asserted. Fungal mycelial cord formation traitmech:000669 now represents the diffuse-front aggregation sense defined by Boddy et al. (2009), DOI:10.1007/s10267-008-0450-4, rather than silently equating the two names. Its experimental examples do not resolve all historical usage. Keep this terminology/hierarchy question OPEN: neither equivalence, a parent-child relationship nor organism-level disjointness is asserted.

Separate formation from transport, invasion and gene mechanisms.

KNOWLEDGE GAP OPEN fungal-rhizomorph-formation-and-function · raised by codex · 2026-10-07

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

Formation does not by itself prove pathogenicity, low-oxygen adaptation, a fixed invasion force or a universal hollow canal. Pareek et al. distinguish air pores from rhizomorphs; oxygen measurements on cut structures do not show intact-rind permeability. Their Results/Table 1 onset discrepancy remains unresolved. Culture versus field observations and hyphal/tip counts require explicit conditions and denominators. Physical growth and aeration have experimental support, but a formation-regulatory graph requires further primary perturbation evidence and authority-verified protein examples. No complete protein pathway is inferred from expression, gene possession, osmolyte composition or structure alone. The graph is deferred, not claimed to be biologically absent.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Added fungal rhizomorph formation with four directly checked source snippets, a provenance-qualified 930199KGS example and explicit terminology, hierarchy and experimental limits. Ignored-and-hidden searches found no exact existing trait. Reserved METPO:1061500 in v538; existing records unchanged and protein-level formation mechanism deferred.

  2. · LINKED_SCOPE_DISCUSSION · codex

    Linked the rhizomorph/cord scope discussion to new traitmech:000669. Preserved the attributed conflicting usages, OPEN status and all existing identity, evidence and example fields; no synonym, hierarchy or disjointness axiom was introduced.

Recorded curation sessions

  • · codex
    • CREATE — Add source-qualified fungal rhizomorph formation

      Added traitmech:000662 as a PROPOSED morphology phenotype with four directly checked DOI-backed snippets of 16, 21, 25 and 22 words. The canonical Armillaria luteobubalina example is qualified to isolate 930199KGS and primary fruit-body provenance; NCBI confirms species 153913. Retained the culture/field distinction, conflicting pigment terminology and Results/Table 1 onset discrepancy. Reserved METPO:1061500 in proposal v538. Ignored-and-hidden searches found no exact existing trait. Writer dry-run, exact source comparisons and 20 focused tests passed; broader validation and PR review remain pending.

    Read this curation session
  • · codex
    • EDIT — Link the cord-formation record without resolving historical terminology

      Appended a link to traitmech:000669 in the existing fungal-rhizomorph-scope-and-hierarchy discussion. Its status remains OPEN. All existing identity, definition, evidence, examples, parents and old history remain unchanged. No equivalence, subclass or organism-level disjointness axiom was introduced. The writer guards the complete semantic preimage, supports exact replay and prevalidates both outputs before writing.

    Read this curation session