identifier: traitmech:000608 label: heterokaryosis definition: A fungal phenotype characterized by the coexistence of genetically distinct nuclei within a shared cytoplasm. definition_source: DOI:10.1098/rspb.2022.0971 trait_category: GENOMICS term_kind: CLASS mapping_status: PROPOSED parent_traits: - METPO:1000059 evidence: - reference: DOI:10.1098/rspb.2022.0971 snippet: Heterokaryosis is a system in which genetically distinct nuclei coexist within the same cytoplasm. notes: 2022 primary study, PMID:35946150. Exact span of the directly retrieved Europe PMC abstract. Introduction, Methods, Results and Discussion were read in the PMC9363985 full-text XML; actual figures and supplements were not inspected. Neurospora tetrasperma lineages L1, L6 and L10 were reconstituted from homokaryotic components, with DNA-ratio validation. Developmental stage and lineage affect expression; global transcription does not diagnose heterokaryosis by itself. L10 heterokaryons can remain largely sterile despite containing both mating types. Expression correlations do not establish a protein-resolved regulatory mechanism. - reference: DOI:10.1098/rspb.2014.0084 snippet: A heterokaryon is a tissue type composed of cells containing genetically different nuclei. notes: Samils et al. (2014), PMID:24850920. Exact span of the directly retrieved Europe PMC abstract. Main-text Methods, Results and Discussion were read at PMC4046401; actual figures and supplements were not visually inspected. The study assays natural N. tetrasperma heterokaryons from lineages L1, L6 and L7 with multiple mating-type-linked SNPs. Bulk DNA ratios and RNA expression are different readouts; they do not count nuclei in every cell. The snippet names the tissue, whereas this record denotes the phenotype. - reference: DOI:10.1016/j.fgb.2018.01.005 snippet: Shifts in fungicide sensitivity and microsatellite genotypes indicated that heterokaryons could adapt to changes in fungicide pressure. notes: Kessler et al. (2018), PMID:29331685. Exact span of the directly retrieved Europe PMC abstract. Methods and relevant Results and Discussion were read in the author-hosted PDF at https://researchmap.jp/umassturfpathology/published_papers/2317022/attachment_file.pdf; actual Figures 5-6 were inspected, but other figures and supplements remain uninspected. Sclerotinia homoeocarpa field isolates were paired in vitro; fluorescent nuclear imaging used engineered derivatives. Tagged histones can move through shared cytoplasm into other nuclei, so dual fluorescence alone does not establish nuclear fusion or genotype. Microsatellite and SNP assays provide complementary evidence, with detection-limit qualifications. Fungicide responses are condition-specific, not defining properties of every heterokaryon; parasexuality was suspected, not demonstrated. canonical_examples: - taxon_id: NCBITaxon:40127 taxon_label: Neurospora tetrasperma reference: DOI:10.1098/rspb.2014.0084 note: 'Qualified example: natural heterokaryon P581 (lineage L6), Lihue, Hawaii. Primary provenance is Methods 2a and Table 1 at https://pmc.ncbi.nlm.nih.gov/articles/PMC4046401/. FGSC 2508 and 2509 are its homokaryotic components, not identifiers for the heterokaryon. The study measures cultured mycelial and sexual tissues at 25 C, not an in-situ nuclear census. This does not assert that all isolates or life stages are heterokaryotic. NCBI taxonomy 40127 resolves to the active species name on 2026-10-04.' discussions: - discussion_id: heterokaryosis-trait-scope prompt: Keep nuclear coexistence distinct from copy number and reproductive processes. kind: CURATION_TODO status: OPEN rationale: This is a reusable genomic phenotype, not a locus or sequence feature. GENOMICS is a filesystem category, not an ontology parent. Genetically distinct nuclei sharing cytoplasm differ from genome-copy number, multinucleation alone, hyphal fusion, postfusion incompatibility and a complete parasexual cycle. Those traits are not is-a parents. Do not require exactly two nuclei, diploidy, a fixed nuclear ratio, universal self-fertility or fungicide resistance. Heterokaryon names a structure, not an automatically exact phenotype synonym. The fungal scope reflects the cited studies; broader terminology and external mappings require authority-level interpretation before adding synonyms or xrefs. posed_by: codex posed_date: '2026-10-04' - discussion_id: heterokaryosis-mechanism-and-readouts prompt: Resolve molecular mechanisms and nuclear identity with independent readouts. kind: CURATION_TODO status: OPEN rationale: Complete unread figures and supplements before extending quantitative or causal claims. Fluorescent protein localization, DNA genotype and RNA expression are different readouts; label exchange must not be interpreted as nuclear fusion. Negative allele detection does not by itself prove biological absence. Resolve native protein identities and experimentally supported edges before adding a mechanistic graph; do not use NONMECHANISTIC to bypass missing grounding. Keep the 2014 natural P581 example separate from reconstituted 2022 cultures and engineered 2018 imaging strains. Verify current taxonomic placement and strain provenance before adding further taxa. posed_by: codex posed_date: '2026-10-04' curation_history: - timestamp: '2026-10-05T00:29:53Z' curator: codex action: MINTED_TRAITMECH_ID changes: Added heterokaryosis with three primary DOI-backed references and exact abstract snippets. Separated nuclear coexistence from ploidy, fusion, incompatibility and parasexual reproduction. Added a qualified natural P581 Neurospora tetrasperma example after primary strain-provenance and NCBI taxonomy checks. Ignored-and-hidden repository searches and structured METPO review found no exact record. Reserved METPO:1056200 in v485 under released phenotype. Retained source-access and experimental-readout limits; external mappings and protein-resolved mechanisms remain unresolved. llm_assisted: true