TraitMech

TraitMech › PHYSIOLOGY

gravitropism

traitmech:000599 · CLASS · PROPOSED

A phenotype in which growth is directionally oriented or reoriented in response to gravity.

Trait evidence (3)

  • DOI:10.4161/cib.22291
    Phycomyces sporangiophores grow in the air and display negative gravitropic bending upon displacement from vertical position.

    Intracellular Reorganization upon Gravistimulation; exact contiguous Europe PMC full-text XML (PMID:23650568; PMC3642927). The full article and all three figure images were inspected. Figure 1 shows bending growth of an intact wild-type stage I sporangiophore after a 45-degree tilt; no strain identifier is given. Figure 2 concerns intracellular reorganization, and Figure 3 measures touch-induced ion fluxes, not a gravity assay. The author explicitly leaves open whether vacuolization reflects gravity signaling or coincident development. The article declares no supplement; the Europe PMC supplementaryFiles download contained ordinary figure assets.

  • DOI:10.1078/0176-1617-01082
    The threshold for the polar angle of the wild type NRRL 1555 (with crystals) is near 8 x 10(-2) x g.

    Abstract, exact-matched at Europe PMC (PMID:15266721). A clinostat centrifuge measures negative gravitropic bending of Phycomyces blakesleeanus sporangiophores. Polar angle and aiming-error angle are distinct readouts; the quoted value belongs to the wild-type polar angle, not the mutant strains or aiming error. It is assay-specific, not a universal threshold. Subscription full text and figures were not inspected.

  • DOI:10.1007/s004250050744
    In rhizoids, positive gravitropic curvature is caused by differential growth limited to the opposite subapical flanks of the apical dome

    Abstract, exact-matched at Europe PMC (PMID:10550622). The primary Chara study describes downward-positive rhizoid growth and upward-negative protonematal growth. This supports polarity-neutral terminology, not positive gravitropism in Phycomyces. The remainder of the quoted sentence excludes displacement of the rhizoid growth centre, calcium gradient or channels. No Chara mechanism or canonical taxon is transferred to the fungus; full text and figures were not inspected.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.4161/cib.22291

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.

  • Phycomyces blakesleeanus NRRL 1555(-) NCBITaxon:763407 DOI:10.1078/0176-1617-01082 Wild-type sporangiophore negative gravitropic bending in the clinostat-centrifuge study, with a source-qualified polar-angle threshold. This is not a mutant example and is not assigned the unnamed 2013 study's stage I observations. Natural-isolate provenance: DOI:10.1128/EC.00203-13, Materials and Methods, Strains and growth conditions (https://pmc.ncbi.nlm.nih.gov/articles/PMC3910969/); NRRL1555 is distinguished from backcrossed A56. Exact strain name and rank resolved directly at NCBI Taxonomy on 2026-10-04.

Discussions and Knowledge Gaps (2)

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

Keep gravity-guided growth separate from swimming and passive motion.

CURATION TODO OPEN gravitropism-growth-and-direction-boundaries · raised by codex · 2026-10-04

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.

The class includes positive or negative directional growth without requiring both in one organism or condition. It is not gravitaxis (swimming orientation), gravikinesis (propulsion-speed change), passive settling, flotation or sagging, or gravity-dependent growth rate alone. The Phycomyces evidence here is negative. Resolve phenotype-level external equivalences before adding xrefs or synonyms.

Discriminate gravity signaling from touch and coincident development.

CURATION TODO OPEN gravitropism-native-mechanism-grounding · raised by codex · 2026-10-04

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.

Bending observations do not resolve a complete molecular mechanism. Vacuolization can coincide with development; touch-induced ion fluxes do not establish gravity-triggered channel activity. The 2004 abstract compares strains with and without crystals but does not identify a universal sole gravity sensor. Inspect its full text and resolve eligible taxon-paired protein accessions before adding a mechanistic graph. Do not use NONMECHANISTIC to bypass grounding requirements or transfer Chara signaling to fungi.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Added gravitropism with two primary fungal studies, a primary direction-terminology source and exact snippets. Ignored-and-hidden novelty searches and structured OWL review found no exact record or METPO term. Reserved METPO:1055300 in v476. Kept growth distinct from locomotion and passive motion; inspected the 2013 full text and figures. Added a natural NRRL1555 exemplar tied only to the 2004 assay, and deferred unresolved mechanisms.