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A zygospore is a diploid reproductive stage in the life cycle of many fungi and protists.Zygospores are created by the nuclear fusion of haploid cells. In fungi, zygospores are formed in zygosporangia after the fusion of specialized budding structures, from mycelia of the same (in homothallic fungi) or different mating types (in heterothallic fungi), and may be chlamydospores. [1]
Meiosis usually occurs before zygospore germination and there are a few main types of distinguishable nuclear behavior. Type 1 is when the nuclei fuse quickly, within a few days, resulting in mature zygospore having haploid nuclei. Type 2 is when some nuclei do not pair and degenerate instead, meiosis is delayed until germination.
Gametangia are haploid multinuclear cells equivalent to gametes. The two gametangia fuse to form an immature zygospore. Initially the developing zygospore contains thousands of nuclei contributed by the gametangia. During the course of zygospore maturation and dormancy, lasting several months, most nuclei are degraded.
The zygospore forms through the isogamic fusion of two cells (motile single cells in Chlamydomonas) or sexual conjugation between two hyphae (in zygomycota). Plasmogamy is followed by karyogamy, therefore zygospores are diploid . They will undergo zygotic meiosis upon germinating.
The gametangium develops into a zygospore, a thick-walled spore formed by the union of gametes. When the zygospore germinates, it undergoes meiosis, generating new haploid hyphae, which may then form asexual sporangiospores. These sporangiospores allow the fungus to rapidly disperse and germinate into new genetically identical haploid fungal ...
Species of Mortierellomycotina only form microscopic colonies, but some make multicellular sporocarps. [15] Mucoromycotina sexual reproduction is by prototypical zygospore formation and asexual reproduction and involves the large production of sporangia.
One cell each from opposite lined filaments emits tubular protuberances known as conjugation tubes, which elongate and fuse to make a passage called the conjugation canal. The cytoplasm of the cell acting as the male travels through this tube and fuses with the female cytoplasm, and the gametes fuse to form a zygospore.
The zygote develops a resistant cell wall, forming a single-celled zygospore, the characteristic that gives its name to this group of fungi. Meiosis occurs within the zygospore (see article Phycomyces). Upon germination, a new haploid mycelium or sporangium is formed. Some species are homothallic.