identifier: traitmech:000597
label: chemotropism
definition: A phenotype in which polarized growth is directionally biased in response
  to a spatial chemical gradient.
definition_source: DOI:10.1371/journal.pbio.3002726
trait_category: PHYSIOLOGY
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- METPO:1000059
evidence:
- reference: DOI:10.1371/journal.pbio.3002726
  snippet: Notably, many hyphae changed direction near the boundary, opting to remain
    in the pH 6.5 layer (Fig 3B).
  notes: 'Results, Chemotropism to low pH; exact span in Europe PMC full text PMC11288418
    (PMID:39078817), published 2024-07-30. The compared layers are pH 6.5 and 8. Figure
    3 was visually inspected: tip trajectories support directional growth, not only
    greater biomass. Main Results and the primary abstract describe lower-pH preference
    in these comparisons; the separate summary abstract''s acidic-pH avoidance wording
    conflicts with them. Growth inhibition at pH 3 and carbon-source growth differences
    confound those comparisons. The nitrogen Results separately report negative chemotropism.
    S1 Table (10.1371/journal.pbio.3002726.s002), inspected as PDF text and image,
    lists engineered backgrounds including TH122; no natural canonical strain is inferred.
    Other supplements and movies were not inspected.'
- reference: DOI:10.1038/s41598-020-67597-z
  snippet: They respond to changes in their environment by directing hyphal growth
    towards or away from a range of chemical stimuli.
  notes: Introduction, first paragraph; They refers to filamentous fungi. Exact span
    in Europe PMC full text PMC7329813 (PMID:32612109). This supports the polarity-neutral
    growth definition. The first Results subsection reports directional growth of
    Fusarium graminearum towards methionine, while rapid growth with other tested
    nitrogen compounds was not significantly directional. Table 1 identifies GZ-3639
    as wild type, but natural provenance and an exact NCBI identity were not independently
    verified. Figures and supplements were not visually inspected. The paper's receptor
    and infection findings are not transferred into a universal chemotropism mechanism
    or canonical example.
discussions:
- discussion_id: chemotropism-growth-and-source-boundaries
  prompt: Preserve direction, growth-rate and source-summary distinctions.
  kind: CURATION_TODO
  status: OPEN
  rationale: This class covers positive and negative chemical-gradient responses of
    polarized growth, not whole-cell locomotion. Use phenotype rather than motile
    as the parent. Neither increased biomass, faster extension nor asymmetric branching
    alone establishes directed growth. Keep chemotaxis, contact guidance and electric-field
    growth distinct. The Yamamoto summary abstract conflicts with the main Results
    on the pH-response direction; retain the inspected Results and Figure 3 context
    rather than silently harmonizing them. External equivalences and lexical variants
    require separate authority and scope checks.
  posed_by: codex
  posed_date: '2026-10-04'
- discussion_id: chemotropism-strain-and-mechanism-grounding
  prompt: Resolve natural strain provenance and accession-level mechanism evidence.
  kind: CURATION_TODO
  status: OPEN
  rationale: Keep laboratory-strain observations as qualified evidence. Verify natural
    provenance and NCBI identities before adding canonical examples; wild-type labels
    and no-auxotrophy controls do not establish an unengineered strain. The Aspergillus
    PmaA perturbation also affects growth and acid tolerance, so it does not isolate
    a dedicated chemical sensor. Inspect remaining figures and supplements and resolve
    taxon-paired protein accessions before adding a causal graph. Do not generalize
    stimulus-specific perturbations into a universal pathway or use a NONMECHANISTIC
    graph to bypass missing molecular evidence.
  posed_by: codex
  posed_date: '2026-10-04'
curation_history:
- timestamp: '2026-10-04T13:41:09Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Added chemotropism with two primary DOI citations and exact full-text snippets.
    Ignored-and-hidden novelty searches and structured OWL review found no exact record
    or METPO term. Reserved METPO:1055100 in v474. Distinguished polarized growth
    from locomotion and growth-rate changes; retained both gradient directions and
    documented conflicting summary wording. Inspected Aspergillus Figure 3 and S1
    strain table. Deferred natural canonical examples and accession-level causal mechanisms.
  llm_assisted: true
- timestamp: '2026-10-04T13:44:00Z'
  curator: codex
  action: CORRECT_EVIDENCE_SNIPPET
  changes: Raw JATS matching caught a dropped figure pointer in the uncommitted Yamamoto
    draft quote. Restored (Fig 3B) before the sentence-ending period to preserve the
    contiguous source span.
  llm_assisted: true