identifier: traitmech:000594
label: thigmotropism
definition: A phenotype in which polarized growth is directionally reoriented in response
  to physical contact with surface topography.
definition_source: DOI:10.1080/02681219280000621
trait_category: PHYSIOLOGY
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- METPO:1000059
evidence:
- reference: DOI:10.1080/02681219280000621
  snippet: The response was likely to be due to contact guidance (thigmotropism) and
    not chemotropism towards the nutrients
  notes: Abstract, exact-matched at Europe PMC (PMID:1287165); full text not inspected.
    Candida albicans hyphae entered membrane pores after contacting their lips, including
    from the underside while growing away from nutrient agar. This supports the authors'
    contact-guidance interpretation, not exclusion of every chemical influence or
    proof of tissue invasion in vivo.
- reference: DOI:10.1099/00221287-144-3-689
  snippet: both compounds reduced the percentage of hyphae reorienting on contact
    with a ridge without markedly affecting hyphal extension rate
  notes: Abstract, exact-matched at Europe PMC (PMID:9534238); full text not inspected.
    The compounds are GdCl3 and verapamil at the tested low concentrations. Reorientation
    and extension rate are distinct readouts. Pharmacological attenuation and membrane
    channel recordings suggest channel involvement but do not identify a unique molecular
    mechanosensor.
- reference: DOI:10.1016/j.cub.2006.12.043
  snippet: The establishment and maintenance of directional growth in relation to
    these environmental cues was Ca(2+) dependent.
  notes: Abstract, exact-matched at Europe PMC (PMID:17275302). PMC1885950 full text
    distinguishes contact-dependent thigmotropism from electric-field galvanotropism.
    In the reported ridge assays, channel-component mutations reduced reorientation
    without reducing hyphal extension rates. Calcineurin was required for cathodal
    emergence but not thigmotropism; do not transfer that pathway requirement between
    the two responses. Localized channel activation and calcium influx remain a proposed
    model, not a universal mechanism established in every microbe. Supplement not
    inspected.
- reference: DOI:10.1111/cmi.12369
  snippet: In vitro, hyphal tips reorient thigmotropically on contact with small obstacles.
  notes: Abstract, exact-matched at Europe PMC (PMID:25262778). PMC4371639 full text,
    Fig. 6 and supplementary Table S1 were inspected. Adhesion or friction sufficient
    to oppose forward growth supported acute tip reorientation; less constrained hyphae
    instead bent subapically. Tip contact alone was insufficient in these assays.
    Table S1 lists CAI4/CIp10, BWP17 and engineered derivatives, including fluorescent
    reporters and an rsr1 deletion; the paper's wild-type designation is not proof
    of natural strain provenance. Spitzenkorper position correlated with growth but
    was not an absolute predictor. Force magnitudes are not curated because main-text
    and supplementary Fig. S2 units disagree. Movies were not inspected.
discussions:
- discussion_id: thigmotropism-growth-and-contact-boundaries
  prompt: Keep contact-directed growth distinct from locomotion and passive bending.
  kind: CURATION_TODO
  status: OPEN
  rationale: Polarized growth reorientation is not whole-cell locomotion, so the parent
    is phenotype, not motile. Filament shape alone does not imply contact sensitivity,
    and the existing mycelial-growth record is explicitly bacterial. Do not equate
    this trait with thigmotaxis, stiffness-gradient migration, electric-field growth,
    generic adhesion or contact-induced differentiation. Passive bending, growth rate
    changes and incidental alignment alone are insufficient. The fungal observations
    do not demonstrate a universal mechanosensor or establish tissue invasion in vivo.
    External equivalences and lexical variants need separate authority and scope checks.
  posed_by: codex
  posed_date: '2026-10-04'
- discussion_id: thigmotropism-strain-and-mechanism-grounding
  prompt: Resolve natural strain provenance and protein-level mechanism evidence.
  kind: CURATION_TODO
  status: OPEN
  rationale: Retain the reported Candida albicans observations as qualified evidence.
    The inspected strain table includes engineered backgrounds and fluorescent reporters;
    verify direct measurements in naturally occurring strains and NCBI identities
    before adding canonical examples. Resolve taxon-paired protein accessions and
    distinguish channel deletion evidence from inhibitor specificity and proposed
    localized calcium signals before adding a causal graph. Keep calcineurin's galvanotropic
    role separate from the reported thigmotropic response. Rsr1-dependent polarity
    positioning does not make Spitzenkorper position an absolute predictor of growth
    direction. Inspect remaining full texts and supplements before strengthening these
    claims; no NONMECHANISTIC graph should bypass missing protein or taxon grounding.
  posed_by: codex
  posed_date: '2026-10-04'
curation_history:
- timestamp: '2026-10-04T10:24:00Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Added thigmotropism with four primary DOI citations and exact abstract
    snippets. Ignored-and-hidden novelty searches and structured OWL review found
    no exact record or METPO term. Reserved METPO:1054800 in v471. Distinguished contact-directed
    polarized growth from locomotion and passive bending. Inspected two full texts
    plus the Thomson Fig. 6 and supplementary strain table. Deferred natural canonical
    examples and accession-level mechanism grounding; did not infer them from engineered
    strains.
  llm_assisted: true