identifier: traitmech:000675
label: cyanobacterial false branching
definition: A morphological phenotype in which a filamentous cyanobacterium forms
  an apparent branch by trichome-bundle partitioning or lateral trichome protrusion
  without generating a branch-point cell connecting at least three neighboring cells
  at that junction.
definition_source: DOI:10.1127/algol_stud/83/1996/303
trait_category: MORPHOLOGY
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- METPO:1000059
evidence:
- reference: DOI:10.1127/algol_stud/83/1996/303
  snippet: Two basic types of false branching (by bundle partitioning and by lateral
    trichome protrusion)
  notes: Golubic et al. (1996), scientific abstract directly read on the publisher
    page https://www.schweizerbart.de/papers/algol_stud/detail/83/91090/Developmental_aspects_of_branching_in_filamentous_.
    Crossref confirms DOI, title and authors. The developmental analysis distinguishes
    false from true branching by branch-point cells contacting at least three neighbors.
    This terminology authority supports both listed modes, not only sheath rupture
    following necridium formation. Full article and figures were not inspected; no
    new experimental replication or universal molecular mechanism is inferred from
    the abstract.
- reference: DOI:10.5507/fot.2021.017
  snippet: initiation of branching after disintegrating of sheath at the site of a
    necridia cell
  notes: Tawong et al. (2022), Figure 1k caption, article page 82 in https://fottea.czechphycology.cz/pdfs/fot/2022/01/05.pdf
    (PDF page 5); actual Figure 1 panels and Methods/Results read. Source grammar
    is retained. Results page 81 points to Figs 2e-k for false branching, but the
    microscopy is Figure 1e-k; Figure 2 is phylogeny. NUACC05/06 show single and binary
    false branches associated with separation, heterocytes and loop rupture. The captioned
    necridium route is not required for every branch or for bundle partitioning.
- reference: DOI:10.1111/jpy.13256
  snippet: False branches developed adjacent to necridic cells or heterocytes, or
    by separation of vegetative cells at compression folds in the trichome.
  notes: Masumoto and Sanders (2022), scientific abstract directly read at https://onlinelibrary.wiley.com/doi/abs/10.1111/jpy.13256.
    Microscopy of lichen cyanobionts reports multiple branching modes within a strain,
    so false and true branching are not disjoint organism-level traits. Secondary
    attachment of freed apical segments is separately described as pseudo-branching;
    that term is not imported as an exact synonym. Full text, figures and supplements
    were not inspected.
canonical_examples:
- taxon_id: NCBITaxon:2929979
  taxon_label: Scytonema foetidum
  reference: DOI:10.5507/fot.2021.017
  note: Example restricted to false-branched filaments of natural isolate NUACC06,
    not every cell or stage. Methods describe single-filament isolation from wet Khek
    River bank soil, Thailand, April 2019, followed by CT/2 liquid culture at 25 degrees
    C with a 12:12 light-dark cycle. Live NCBI Taxonomy efetch https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id=2929979
    confirms this current species name, rank species and NUACC06 type material; it
    is not a strain-rank accession. Taxonomy supports identity, not independent phenotype
    evidence.
discussions:
- discussion_id: false-branching-scope
  prompt: Review a closer multicellular morphology parent and branching terminology.
  kind: CURATION_TODO
  status: OPEN
  rationale: 'Use phenotype METPO:1000059 below quality METPO:1000188. Branched shaped
    METPO:1000687 concerns lateral branches in cell shape, not necessarily this arrangement
    of trichomes; no subclass or equivalence is asserted. The Golubic 1996 definition
    authority includes bundle partitioning as well as lateral protrusion. The Scytonema
    example demonstrates the latter and must not narrow the whole class. Necridium
    formation traitmech:000674 describes a separation cell, not all false branches.
    Hormogonium formation traitmech:000651 describes dispersal filaments, not the
    branching topology. Obsolete cell-arrangement METPO terms redirect to flagellar
    arrangement, which is not a suitable parent here. No exact synonyms, xrefs, SSSOM
    mappings or organism-level disjointness are asserted; historical pseudo-branch
    usages need review. The label is qualified as cyanobacterial false branching because
    the directly read English scientific abstract of Nesterenko et al. (1980), PMID:6782438
    (https://pubmed.ncbi.nlm.nih.gov/6782438/), uses false branching for growth of
    separated cell ends in the organism historically named Brevibacterium helvolum
    ATCC 19239. That distinct usage is not evidence for cyanobacterial trichome development.
    Its full text and modern taxonomic identity were not inspected. No unqualified
    exact synonym or cross-taxon mechanism is asserted. See review issue #1821.'
  posed_by: codex
  posed_date: '2026-10-08'
- discussion_id: false-branching-mechanism
  prompt: Resolve mechanisms separately for each developmental mode.
  kind: KNOWLEDGE_GAP
  status: OPEN
  rationale: The inspected microscopy supports a phenotype and cellular developmental
    routes, not an accession-resolved protein mechanism. Taxonomic sequence markers
    do not establish causality. Do not require necridia, heterocytes, a fixed branch
    count, one division plane, a universal trigger or a fitness benefit. No causal
    graph is proposed pending direct mechanistic evidence and verified protein examples;
    a mechanism is not claimed biologically absent.
  posed_by: codex
  posed_date: '2026-10-08'
curation_history:
- timestamp: '2026-10-08T06:28:38Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Added cyanobacterial false branching with three DOI sources, verbatim snippets
    and a source-qualified NUACC06 example. Ignored-and-hidden searches of current
    main, worktrees and complete open-PR curation snapshots support 000675 and v551
    block 1062800-1062899. Preserved both developmental modes, local branch-point
    scope and uncertainty about protein mechanisms. Existing traits unchanged. Timestamp
    is observed UTC curation time.
  llm_assisted: true
- timestamp: '2026-10-08T06:50:15Z'
  curator: codex
  action: QUALIFY_TRAIT_LABEL
  changes: 'Addressed #1821: qualified the label to its cyanobacterial scope after
    directly checking the non-cyanobacterial usage in PMID:6782438. Preserved definition,
    evidence, example, identifier, proposal block and original curation event. Added
    source-qualified terminology discussion without an unqualified exact synonym.'
  llm_assisted: true