identifier: traitmech:000604
label: positive autotropism
definition: A phenotype in which germ-tube emergence or hyphal extension is directionally
  biased toward neighboring cells or hyphae of the same species.
definition_source: DOI:10.1093/jxb/19.1.125
trait_category: PHYSIOLOGY
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- METPO:1000059
evidence:
- reference: DOI:10.1093/jxb/19.1.125
  snippet: the positive germ-tube, i.e. one beginning more nearly towards its neighbour
  notes: Robinson, Park and Graham (1968), original publisher abstract directly retrieved
    from https://oup.silverchair-cdn.com/article-minimal/447341. The abstract reports
    positive autotropism in Botrytis cinerea on Cellophane over agar and neutrality
    on agar alone. The quoted orientation definition occurs in the mixed-orientation
    spore-pair timing comparison for Rhizopus stolonifer and Mucor plumbeus, both
    described as exhibiting marked negative autotropism. Earlier emergence of the
    positive germ-tube in those pairs does not establish a net positive response in
    either species. The abstract defines positive germ-tube orientation relative to
    the neighboring spore. This supports the terminology and emergence component,
    not later tip bending or completed fusion. Germination timing and cis-ness are
    separate readouts. The full paper, strain provenance and sample sizes were not
    retrieved. No universal chemical mechanism is inferred from the abstract's proposed
    explanations.
- reference: DOI:10.1039/d3lc00859b
  snippet: The hyphae approach each other from opposing directions with occasional
    arrestation of growth and readjustment of the growth direction.
  notes: Richter et al. (2024), Results section on stop-and-go growth before anastomosis;
    directly retrieved Europe PMC full-text JATS, PMC10964749 (PMID:38416560). Culture
    and image-analysis methods, corresponding Discussion and actual Figure 5 were
    inspected. Figure 5a-c shows Rhizophagus irregularis MUCL 43194 approaching before
    fusion; the 21-hour trace is a representative pair, not a replication count. This
    is independent extension evidence interpreted within the directional definition,
    not an assertion that this paper uses the autotropism label. Supplementary methods
    and movies were not retrieved; attachment requests returned access-check HTML
    or HTTP errors.
discussions:
- discussion_id: positive-autotropism-direction-and-fusion-scope
  prompt: Retain the distinction between directional approach and fusion.
  kind: CURATION_TODO
  status: OPEN
  rationale: Initial germ-tube orientation and later hyphal redirection are distinct
    readouts; the definition does not require both in one organism. Hyphal fusion/anastomosis
    is a separate endpoint, not an exact synonym or a prerequisite. Same-species neighbors
    can include branches of one mycelium or separate spores; genetic identity is not
    required by this definition. Do not infer whole-cell taxis, chemotropism, mating
    or a particular self-recognition mechanism. Passive alignment, faster growth and
    contact alone are insufficient. Negative autotropism has the opposite direction,
    not the same phenotype. Resolve external equivalences before adding xrefs or synonyms.
  posed_by: codex
  posed_date: '2026-10-04'
- discussion_id: positive-autotropism-provenance-and-mechanism
  prompt: Verify strain origins, supplements and native signaling mechanisms.
  kind: CURATION_TODO
  status: OPEN
  rationale: Canonical examples await original strain-provenance and NCBI identity
    checks. The 2024 culture method uses transformed chicory roots; this does not
    establish engineering of the fungi. Inspect the original supplements and the 1968
    full paper before quantitative or strain-level enrichment. No universal ligand/receptor
    chain is established by these observations. A causal graph requires directly supported
    native perturbations and taxon-paired protein accessions; NONMECHANISTIC is not
    a grounding bypass.
  posed_by: codex
  posed_date: '2026-10-04'
curation_history:
- timestamp: '2026-10-04T21:04:32Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Added positive autotropism with two directly retrieved DOI-backed sources
    and exact snippets. Distinguished orientation and extension from completed fusion.
    Ignored-and-hidden searches and structured OWL review found no exact term; the
    negative sibling's boundary mention is not a duplicate. Reserved METPO:1055800
    in v481 under released phenotype. Inspected Figure 5 and retained abstract-only,
    representative-pair and unread-supplement limitations. Deferred canonical strains,
    synonyms, external equivalents and causal graphs.
  llm_assisted: true
- timestamp: '2026-10-04T21:35:35Z'
  curator: codex
  action: REFINE_EVIDENCE_SNIPPET
  changes: 'Addressed #1687 by replacing the anaphoric label-only 1968 quote with
    its exact germ-tube orientation definition. Qualified the mixed-orientation timing
    comparison without inferring net positive autotropism in its two negative-response
    species. Retained the separate Botrytis cinerea substrate-dependent observation.'
  llm_assisted: true