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Homothallic refers to the possession, within a single organism, of the resources to reproduce sexually; [1] i.e., having male and female reproductive structures on the same thallus. The opposite sexual functions are performed by different cells of a single mycelium. [2] It can be contrasted to heterothallic. It is often used to categorize fungi.
Heterothallic species have sexes that reside in different individuals. The term is applied particularly to distinguish heterothallic fungi , which require two compatible partners to produce sexual spores, from homothallic ones, which are capable of sexual reproduction from a single organism.
Homothallic species are able to mate with themselves, while in heterothallic species only isolates of opposite mating types can mate. Mating between isogamous fungi may consist only of a transfer of a nucleus from one cell to another. Vegetative incompatibility within species often prevents a fungal isolate from mating with another isolate.
Heterothallic ascomycetes produce gametes, which present a single Mat idiomorph, and syngamy will only be possible between gametes carrying complementary mating types. On the other hand, homothallic ascomycetes produce gametes that can fuse with every other gamete in the population (including its own mitotic descendants) most often because each ...
In the case of homothallic species, mating is enabled between hyphae of the same fungal clone, whereas in heterothallic species, the two hyphae must originate from fungal clones that differ genetically, i.e., those that are of a different mating type.
Those fungi that need a partner to mate are referred to as heterothallic (self-sterile), and those fungi not needing a partner are referred to as homothallic (self-fertile). A study of DNA sequences of mating type loci from different heterothallic and homothallic species in the genus Cochliobolus suggests that homothallism can be derived from ...
These fungi are said to be homothallic, versus the normal heterothallic species with mating types. Others are secondarily homothallic, in that two compatible nuclei following meiosis migrate into each basidiospore, which is then dispersed as a pre-existing dikaryon. Often such species form only two spores per basidium, but that too varies.
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]