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pseudohomothallism

traitmech:000612 · CLASS · PROPOSED

A fungal phenotype enabling a sexual spore carrying separate nuclei of compatible mating types to establish a self-fertile heterokaryotic culture.

Trait evidence (4)

  • DOI:10.5598/imafungus.2015.06.01.13
    self-fertility is the result of the packaging of two independent and opposite mating type nuclei within a single spore

    2015 terminology review, PMID:26203424, PMC4500084. Exact contiguous clause from section s2b Pseudohomothallism, read end-to-end in directly retrieved full-text XML. This supplies definition and homothallism-parent authority, not experimental replication or an abstract quote. The review describes single-spore self-fertility arising from compatible partners packaged as separate nuclei. Its two-nucleus description is not a fixed count for every subsequent spore or mycelial stage; the comparative primary study below documents developmental variation. Occasional self-sterile propagules allow outcrossing. Figure 1 remains uninspected.

  • DOI:10.1093/genetics/143.2.789
    Ascospores of Neurospora tetrasperma normally contain nuclei of both mating-type idiomorphs (a and A), resulting in self-fertile heterokaryons

    Merino et al. (1996), PMID:8725227. Exact opening clause of the scientific abstract directly retrieved from Europe PMC core metadata. The following parenthesis names this sexual system pseudohomothallism. The study compares mating-type chromosome and autosomal sequences from wild-collected self-fertile strains, while distinguishing occasional homokaryotic self-sterile strains capable of outcrossing. Recombination suppression is an evolutionary association in this system, not the definition of every pseudohomothallic fungus. Full text, figures, supplements and strain-level provenance in this paper remain uninspected.

  • DOI:10.1002/dvg.1020150111
    Two basically different modes underlie the delivery of opposite mating type nuclei into each of the four ascospores in the different genera.

    Raju and Perkins (1994), PMID:8187347. Exact sentence of the directly retrieved Europe PMC scientific abstract, which is explicitly truncated at 400 words. Comparative cytology covers N. tetrasperma, G. tetrasperma, P. anserina and P. tetraspora. First-division segregation in Neurospora differs from the second-division program in Podospora and Gelasinospora. The mat-centromere crossover is established for P. anserina but inferred for the other two latter species. Following postmeiotic development, germinating P. anserina ascospores retain three functional nuclei, two of one mating type and one of the other. Do not require exactly two nuclei, four spores, a fixed nuclear ratio, suppressed crossing over or one spindle geometry for the whole trait. Full text, original methods, actual figures and strain provenance remain unread.

  • DOI:10.1371/journal.pgen.1000030
    recombination was assessed in individual sexual progeny originating from a selfed cross of the heterokaryotic mycelia.

    Menkis et al. (2008), PMID:18369449, PMC2268244. Exact contiguous clause of Methods s4d, not an abstract quote. Scientific abstract, Introduction, Results s2b/s2c, Methods s4a/s4c/s4d/s4e and Table 1 including footnotes were read in the full-text XML. Results s2b and Methods s4d assay 152 heterokaryotic sexual progeny of a selfed P581 cross; that selected assay denominator is not the frequency of all heterokaryotic offspring. Table 1 identifies P581 as a wild-type heterokaryon from Lihue, Hawaii, and its P-prefix footnote identifies the Perkins collection from nature. FGSC 2508/2509 are homokaryotic components, not alternative identifiers for the natural heterokaryon. The separate 83-progeny N. crassa introgression experiment is not the native P581 selfing assay. Figures, supplements, Discussion and unread experimental sections remain uninspected; inferred evolutionary history is not a demonstrated universal developmental mechanism.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.5598/imafungus.2015.06.01.13

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.

  • Neurospora tetrasperma NCBITaxon:40127 DOI:10.1371/journal.pgen.1000030 Qualified natural example: heterokaryon P581 from Lihue, Hawaii. Provenance is Table 1 and its Perkins-collection footnote at https://pmc.ncbi.nlm.nih.gov/articles/PMC2268244/. Results s2b and Methods s4d analyze 152 heterokaryotic sexual progeny from selfed P581; this is a selected assay set, not a claim that every spore is heterokaryotic or self-fertile. Methods s4a specifies synthetic cross medium at 25 C for crosses. FGSC 2508 and 2509 are its isolated homokaryotic components and are not the example. Do not extend this observation to every strain or life stage. NCBI taxonomy 40127 resolves to the active species name 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 single-spore self-fertility distinct from nuclear coexistence and MAT content.

CURATION TODO OPEN pseudohomothallism-scope-and-hierarchy · 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.

This reproductive phenotype narrows homothallism (traitmech:000609), not heterothallism or mating-type switching. Heterokaryosis is relevant cellular context but does not alone establish self-fertility. A single sexual spore can carry compatible partners as separate nuclei; MAT sequences in one assembly or multinucleation alone do not establish the trait. Do not require exactly two nuclei throughout development, four spores, one nuclear ratio, universal self-fertility or absence of outcrossing. Resolve secondary homothallism and functional heterothallism usage before assigning exact synonyms, and verify external phenotype/process mappings before adding xrefs. PHYSIOLOGY is a filesystem category. The standalone METPO proposal uses released phenotype, not an unlabeled stub for pending homothallism METPO:1056300; reconcile the narrower hierarchy when that v486 parent is accepted upstream.

Resolve taxon-specific nuclear packaging before adding protein-level causal edges.

CURATION TODO OPEN pseudohomothallism-mechanism-and-readouts · 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.

Complete unread primary experiments, figures and supplements before expanding mechanistic claims. Spindle arrangement, mating-type segregation and nuclear elimination vary across genera and developmental stages; no one meiotic program is universal. Separate observed cytology from inferred crossover events, and sequence divergence from a direct reproductive readout. Keep natural P581 separate from its homokaryotic components and interspecific introgression derivatives. Resolve native protein accessions and source-bounded dependencies before adding a graph; do not use NONMECHANISTIC to bypass missing grounding. Manual full-text matching is not an abstract-resolver VERIFIED verdict.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Added pseudohomothallism with four DOI-backed exact source snippets and qualified natural P581 after primary selfed-progeny, strain-table and NCBI checks. Kept local homothallism parent and reproductive scope separate from MAT content or nuclear count. Ignored-and-hidden novelty searches and structured METPO review found no exact record. Reserved METPO:1056600 in v489 under released phenotype pending acceptance of the narrower parent. Deferred lexical mappings and protein-resolved causal graphs.