Dikaryon
Encyclopedia
Dikaryon is from Greek
, di meaning 2 and karyon meaning nut
, referring to the cell nucleus
.
The dikaryon is a nuclear feature which is unique to some fungi, in which after plasmogamy
the two compatible nuclei of two cells
pair off and cohabit without karyogamy
within the cells of the hyphae, synchronously
dividing so that pairs are maintained in the older cells while newer cells or hyphal tips are also binucleate, i.e. dikaryotic; in the Ascomycota
this attribute of the nuclei to do such is only found in the Ascogenous hyphae but is the dominant phase in the Basidiomycota
. The formation of a dikaryon is a plesiomorphic character for the subkingdom Dikarya
, which covers both the Basidiomycota
and Ascomycota
. The formation of croziers
in the Ascomycota and of clamp connection
s in the Basidiomycota facilitate maintenance of the dikaryons. However, some fungi in each of these phyla
have evolved other methods for maintaining the dikaryons, and therefore neither croziers nor clamp connections are ubiquitous in either phylum.
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
, di meaning 2 and karyon meaning nut
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
, referring to the cell nucleus
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
.
The dikaryon is a nuclear feature which is unique to some fungi, in which after plasmogamy
Plasmogamy
Plasmogamy is a stage in the sexual reproduction of fungi. In this stage, the cytoplasm of two parent mycelia fuse together without the fusion of nuclei, as occurs in higher terrestrial fungi. After plasmogamy occurs, the secondary mycelium forms. The secondary mycelium consists of dikaryotic...
the two compatible nuclei of two cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
pair off and cohabit without karyogamy
Karyogamy
Karyogamy is the fusion of pronuclei of two cells, as part of syngamy, fertilization, or true bacterial conjugation.It is one of the two major modes of reproduction in fungi...
within the cells of the hyphae, synchronously
Synchronization
Synchronization is timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time....
dividing so that pairs are maintained in the older cells while newer cells or hyphal tips are also binucleate, i.e. dikaryotic; in the Ascomycota
Ascomycota
The Ascomycota are a Division/Phylum of the kingdom Fungi, and subkingdom Dikarya. Its members are commonly known as the Sac fungi. They are the largest phylum of Fungi, with over 64,000 species...
this attribute of the nuclei to do such is only found in the Ascogenous hyphae but is the dominant phase in the Basidiomycota
Basidiomycota
Basidiomycota is one of two large phyla that, together with the Ascomycota, comprise the subkingdom Dikarya within the Kingdom Fungi...
. The formation of a dikaryon is a plesiomorphic character for the subkingdom Dikarya
Dikarya
Dikarya is a subkingdom of Fungi that includes the phyla Ascomycota and Basidiomycota, both of which in general produce dikaryons, may be filamentous or unicellular, but are always without flagella. The Dikarya are most of the so called "higher fungi", but also include many anamorphic species that...
, which covers both the Basidiomycota
Basidiomycota
Basidiomycota is one of two large phyla that, together with the Ascomycota, comprise the subkingdom Dikarya within the Kingdom Fungi...
and Ascomycota
Ascomycota
The Ascomycota are a Division/Phylum of the kingdom Fungi, and subkingdom Dikarya. Its members are commonly known as the Sac fungi. They are the largest phylum of Fungi, with over 64,000 species...
. The formation of croziers
Crozier (mycology)
A crozier is an anatomical feature of many fungi in the phylum Ascomycota that form at the base of asci and look like hook-topped shepherd’s staffs or stylized religious crosiers...
in the Ascomycota and of clamp connection
Clamp connection
A clamp connection is a structure formed by growing hyphal cells of certain fungi. It is created to ensure each septum, or segment of hypha separated by crossed walls, receives a set of differing nuclei, which are obtained through mating of hyphae of differing sexual types...
s in the Basidiomycota facilitate maintenance of the dikaryons. However, some fungi in each of these phyla
Phylum
In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....
have evolved other methods for maintaining the dikaryons, and therefore neither croziers nor clamp connections are ubiquitous in either phylum.