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tripolar mating system

traitmech:000618 · CLASS · PROPOSED

A fungal mating-system phenotype in which sexual reproduction occurs between a partner with pheromone/receptor and homeodomain determinants linked in one mating-type region and a partner with those determinants in two unlinked regions.

Trait evidence (2)

  • DOI:10.1128/ec.00271-08
    one of the parents has one contiguous MAT locus (one pole) while the other has two unlinked sex-determining regions (two poles).

    Hsueh et al. (2008), PMID:18723606, PMC2568056. Exact clause in the first tripolar-cross Results subsection, checked against raw PMC HTML; not an abstract quote. Engineered Cryptococcus neoformans strains relocate a homeodomain determinant from MAT to unlinked URA5. Reciprocal crosses with wild-type partners yielded germinating, segregating progeny (Tables 2/3). Actual Figures 1/2 were inspected: Figure 1 shows colony-edge filamentation, whereas Figure 2 is a genotype model, not an observed segregation ratio. Methods, relevant Results and Discussion were read; other actual figures and supplements remain uninspected. These engineered crosses establish functional feasibility, not natural prevalence or a proven ancestral intermediate. The theoretical fertility fractions are not universal measured rates; JF289 also carries multiple SXI2a copies.

  • DOI:10.1128/mbio.00059-26
    the MAT-fused strains were able to successfully mate with the strains in which the P/R and HD are unlinked, constituting a “tripolar” mating.

    Xiong et al. (2026), PMID:41841731, PMC13059729. Exact Results s2-2 clause checked against raw Europe PMC full-text XML; not a scientific-abstract or IMPORTANCE quote. In Cryptococcus amylolentus, engineered MAT-fused derivatives of CBS6039 or CBS6273 mate with an opposite wild-type partner retaining unlinked P/R and HD loci. Results s2-2 reports sexual structures and genotyped germinating progeny; s2-4 reports genome-wide meiotic recombination in 26 tripolar progeny, within a 42-progeny analysis also containing bipolar progeny. Relevant construction, mating and sequencing Methods were read. Figure 2/4 captions were read, but actual figures and supplements remain uninspected after image access failed. Other source sections remain unread. Reduced fusion in bilateral MAT-fused bipolar crosses must not be transferred to these unilateral tripolar crosses.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1128/ec.00271-08

Parent traits (1)

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

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 the cross-level mating phenotype distinct from sequence inventory.

CURATION TODO OPEN tripolar-mating-scope-and-hierarchy · raised by codex · 2026-10-05

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 unit is a mating system or cross with differently organized partners, not a standalone locus or a species-wide assertion about either parental strain. Three poles across the pair do not mean three mating types or three independent factors in each genome. This differs from the uniform single-factor and two-factor systems in traitmech:000616 and traitmech:000615, and from recombination-permitting chromosomal colocation in traitmech:000617. Heterothallic source framing does not make this a universal separate-partner dependence subclass of traitmech:000610; progeny can differ in self-fertility. Use released phenotype METPO:1000059 in record and proposal pending narrower relational-phenotype hierarchy review. PHYSIOLOGY is a filesystem category. No disjointness, fixed fertility ratio, natural prevalence or mandatory evolutionary trajectory is asserted. Resolve lexical and external equivalences before synonyms or xrefs.

Resolve natural examples and source-bounded mechanisms before extension.

CURATION TODO OPEN tripolar-mating-evidence-and-mechanism · raised by codex · 2026-10-05

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.

Both primary studies use engineered partners, so no natural canonical taxon is inferred. Keep genotype, filamentation, spore germination, meiotic segregation and subsequent mating ability separate. The two studies report different self-fertility outcomes for progeny carrying compatible homeodomain determinants; retain strain background and copy-number context rather than generalize sterility. Inspect unread figures, supplements and source sections before more detailed claims or quantitative rates. Resolve native protein accessions and experimentally tested dependencies before causal edges; no NONMECHANISTIC graph bypasses grounding. Manual full-text snippet matches remain distinct from the abstract resolver's actual verdicts.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Added tripolar mating system with two primary DOI-backed sources and verbatim full-text clauses. Kept the cross-level functional phenotype distinct from sequence inventory, natural prevalence and fixed fertility ratios. Ignored-and-hidden novelty and allocation searches found no exact record or ID collision. Reserved METPO:1057200 in v495 under released phenotype. Deferred canonical taxa, lexical mappings and protein graphs, with engineered provenance and unread source material explicit.