identifier: traitmech:000598
label: phototropism
definition: A phenotype in which growth is directionally oriented or reoriented toward
  or away from a light source in response to illumination.
definition_source: DOI:10.1073/pnas.0600633103
trait_category: PHYSIOLOGY
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- METPO:1000059
evidence:
- reference: DOI:10.1073/pnas.0600633103
  snippet: it exhibits phototropism by bending toward near-UV and blue wavelengths
    and away from far-UV wavelengths
  notes: 'Abstract, exact-matched at Europe PMC (PMID:16537433; PMC1450208); it refers
    to Phycomyces blakesleeanus sporangiophore growth. The institutional full-text
    PDF and Figure 1A were inspected: the wild-type control bends toward white light,
    unlike the reduced response of madA mutants. The abstract''s far-UV response is
    not measured in that panel. Methods identify NRRL1555 as the wild-type background
    and distinguish chemically mutagenized derivatives and isogenic A56. Genetic cosegregation
    supports madA involvement, not a complete growth-polarity pathway.'
- reference: DOI:10.1073/pnas.0900879106
  snippet: Phototropism, growth toward light, shares many features in fungi and plants
    but the molecular mechanisms remain to be fully elucidated.
  notes: Abstract, exact-matched at Europe PMC (PMID:19380729; PMC2678449). This passage
    describes the positive case; the Idnurm source establishes the broader directional
    scope. The institutional full-text PDF and Figures 2B and 4 were inspected. Phototropic
    responses cosegregate with madB alleles; MADA-MADB interaction assays use yeast
    and E. coli, not the native fungus. The Discussion leaves rapid bending mechanisms
    unresolved. Transcription measurements are not themselves directional-growth readouts.
    The supplementary strain table and figures were not accessible and were not inspected.
- reference: DOI:10.1128/EC.00203-13
  snippet: These strains are wild isolates, except for A56.
  notes: Materials and Methods, Strains and growth conditions; exact contiguous raw
    PMC HTML text (PMID:24243797; PMC3910969). The preceding sentence includes NRRL1555
    in the named strains; the following sentence distinguishes backcrossed A56. This
    supports natural-isolate provenance for the NRRL1555 exemplar, not an independent
    phototropism experiment.
canonical_examples:
- taxon_id: NCBITaxon:763407
  taxon_label: Phycomyces blakesleeanus NRRL 1555(-)
  reference: DOI:10.1073/pnas.0600633103
  note: 'Wild-type sporangiophore growth toward white light in Figure 1A, with NRRL1555
    background identified in Methods; not the madA mutants or backcrossed A56. Independent
    natural-isolate provenance: DOI:10.1128/EC.00203-13, Materials and Methods (https://pmc.ncbi.nlm.nih.gov/articles/PMC3910969/).
    Strain-level identity and exact name resolved at NCBI Taxonomy on 2026-10-04.
    No invariant wavelength or response direction is asserted.'
discussions:
- discussion_id: phototropism-growth-and-direction-boundaries
  prompt: Preserve growth, locomotion and response-direction distinctions.
  kind: CURATION_TODO
  status: OPEN
  rationale: The class includes growth toward or away from light without requiring
    both responses in one organism or condition. It is not phototaxis (active locomotion),
    photokinesis (locomotion-speed change), phototrophy (energy acquisition), or light-dependent
    growth rate or development alone. Use phenotype rather than motile as the parent.
    A blue-light receptor homolog alone does not establish this phenotype. Resolve
    phenotype-level external equivalences separately before adding synonyms or xrefs.
  posed_by: codex
  posed_date: '2026-10-04'
- discussion_id: phototropism-native-mechanism-grounding
  prompt: Separate heterologous interaction assays from native growth control.
  kind: CURATION_TODO
  status: OPEN
  rationale: Retain genetic and heterologous evidence at its measured scope. Neither
    a yeast interaction assay nor copurification in E. coli proves the native light-dependent
    interaction or the full route from photoreception to asymmetric growth. Inspect
    the unavailable Sanz supplement and newer primary work, and resolve eligible taxon-paired
    protein accessions before adding a mechanistic graph. Do not transfer plant phototropin
    signaling to fungi or use NONMECHANISTIC to bypass protein-grounding requirements.
  posed_by: codex
  posed_date: '2026-10-04'
curation_history:
- timestamp: '2026-10-04T14:39:25Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Added phototropism with two primary phenotype studies, a primary strain-provenance
    citation and exact snippets. Ignored-and-hidden novelty searches and structured
    OWL review found no exact record or METPO term. Reserved METPO:1055200 in v475.
    Retained both growth directions and distinguished locomotion and energy acquisition.
    Inspected primary figures; added NCBI-resolved natural NRRL1555 exemplar and deferred
    native protein-level mechanisms and unavailable supplements.
  llm_assisted: true