The life cycle of fungi always goes with alternation of diploid and haploid phases. In all species of fungi necessarily occurs an alternation of hapl

Life cycle of fungi

The life cycle of fungi always goes with alternation of diploid and haploid phases. In all species of fungi necessarily occurs an alternation of haploid and diploid generations.

In the life cycle of fungi diploid stage — is only a state of zygote, which, like in unicellular, is short-lived and completes with meiosis. For example, in spring morel mushrooms (diagram 96), that are related to the higher sac fungi Ascomycetes (from Greek “askos” – “sac, bag” and “mikes” – “mushroom”), the life cycle is as follows. From haploid “+” and “-“ spores develop haploid hyphae, which can reproduce by fragmentation. However, over time on them form male and female sexual organs and sexual process begins. True fertilization does not occur as the male and female nuclei do not merge, but only approach each other in the center of the cell. At this stage of morel life cycle its mycelium cells, cannot be called neither diploid nor haploid. With the growth, accompanied by mitotic divisions of the haploid nuclei, on the end parts of the mycelium (called asci) nevertheless occurs nuclear fusion of parent mycelia and zygote obtains. By meiosis they are divide into four cells, each of which then is mitotically divide into two, whereby from one zygote ultimately form eight spores. Taken from http://worldofschool.org

Diagram 96. The life cycle of morels mushrooms: 1 — haploid spores, falling to the ground; 2-3 — development of haploid hyphae; 4 — sexual process, leading to the formation of dual-nuclei cell; 5-6 — formation and maturation of fruit bodies; 7-8 — the first and the second stages of meiosis in asci, leading to the formation of four haploid cells; 9 — mitotic division, leading to the appearance of eight haploid spores in each ascus
Questions:
  • What features of fungi life cycle?