Нейроспора: характеристики и жизненный цикл грибов рода Neurospora

Genus of fungi
Automatic taxobox
| image = Neurospora crassahyphae. jpg
| image caption = Neurospora crassa
| taxon = Neurospora
| authority = Shear & B. O. Dodge (1927)
| type species = Neurospora sitophila
| type species authority = Shear & B. O. Dodge (1927)
| synonyms ref =

Neurospora species are molds with broadly spreading colonies, with abundant production of ascomata. Ascomata are superficial or immersed, perithecial and ostiolate or cleistothecial and non ostiolate, hairy or glabrous, dark coloured. Peridium membranaceous, asci cylindrical, clavate or subspherical, with a persistent or evanescent wall, usually with a thickened and non amyloid annular structure at the apex, usually 8 spored. Ascospores broadly fusiform, ellipsoidal, or nearly spherical, unicellular, hyaline to yellowish brown or olive brown, becoming dark and opaque at maturity, ascospore wall with longitudinal ribs or pitted, occasionally nearly smooth, 1–2 (but rarely up to 12) germ pores disposed at the ends of the ascospores, gelatinous sheaths or appendages are absent. Anamorphs are known in only a relatively small number of species, which belong to the fungi imperfecti genus Chrysonilia. The type species of the genus is Neurospora sitophila Shear.

In the heterothallic species Neurospora crassa, the interaction of haploid strains of opposite mating type is necessary for the occurrence of sexual reproduction and the production of ascospores by meiosis. Ascospores then restore haploid individuals of either mating type. The life cycle phase is thus predominantly haploid, however, upon mating, the nuclei do not immediately fuse: karyogamy is delayed until the very onset of meiosis. The resulting mycelium is called a heterokaryon and is neither diploid nor haploid. The genus Neurospora also includes homothallic species in which a single haploid individual carries both mating type loci and can undergo self fertilization leading to meiosis and sexual reproduction. Neurospora africana is an example of such a species. Additionally, some "Neurospora" species are said pseudohomothallic. They carry both mating types, but in separate nuclei in the same individual. Two haploid nuclei originating from the same meiosis are packaged into one ascospore. The individual is thus permanently heterokaryotic. Examples of this mating system include "Neurospora tetrasperma" and "Neurospora tetraspora". Because heterothallic species necessarily undergo some degree of outcrossing they may benefit from a higher efficiency of selection because of higher effective recombination rates. In contrast, pseudohomothallic and homothallic species do not outcross (or rarely) and do not experience these benefits: in homothallics a reduced efficiency of negative selection has been shown. However, both hetero and pseudohomothallic species benefit from the masking of deleterious recessive alleles in the heterokaryotic phase. In addition, all species derive the benefits of meiosis that include the removal of stress induced DNA damages by homologous recombinational repair, and the formation of stress resistant ascospores.