Fungi exhibit both sexual and asexual reproduction, with all fungi producing spores as a key reproductive strategy. Asexual fungi, known as deuteromycetes, rely solely on this method. The structures that produce spores are commonly referred to as fruiting bodies, although more technical terms exist for specific types. Unlike many organisms that have distinct male and female forms, fungi possess various mating types that do not show morphological differences. Instead, fungi communicate their mating types through pheromones, which are chemical signals that facilitate mating interactions.
Fungi can have numerous mating types within a single species, sometimes numbering in the thousands, which complicates the traditional male-female classification. The process of fertilization in fungi begins with the fusion of hyphae, a stage known as plasmogamy, where the cytoplasm of two cells merges without the immediate fusion of their nuclei. This results in a heterokaryotic cell, which contains genetically distinct nuclei, often represented as n + n, where n indicates haploid nuclei. When two haploid nuclei eventually fuse, this process is termed karyogamy, leading to the formation of a diploid zygote.
The zygote, typically the only diploid stage in most fungi, develops into a fruiting body, such as a mushroom, which then releases spores. These spores are dispersed through various means, including rain and insects, and upon germination, they form new hyphae, continuing the life cycle. The cycle involves repeated stages of hyphal fusion, plasmogamy, karyogamy, and spore production.
Chytrids represent an exception in fungal reproduction, as they exhibit an alteration of generations, similar to some plants. This unique reproductive strategy includes both a multicellular sporophyte and gametophyte generation. Chytrids are characterized by their flagellated spores and gametes, known as zoospores, which differentiate them from other fungi that follow the more common reproductive cycle.