Write down the salient features of Ascomycetes.

Explanation

`**` Ascomycetes include a wide range of fungi such as yeasts, powdery mildews, cup fungi , morels and so on.
`**` Although majority of the species live in terrestrial environment, some live in aquatic environments both fresh water and marine.
`**` The mucelium is well developed, branched with simple septum.
`**` Majority of them are saprophytes but few parasites are also known. (Powdery mildew - Erysiphe).
`**` Asexual reproduction takes place by fission, budding, oidia, conidia and chlamydospore.
`**` Sexual reproduction takes place by the fusion of two compatible nuclei.
`**` Plasmogamy is not immediately followed by karyogamy, instead a dikaryotic condition is prolonged for several generations.
`**` A special hyphae is formed.
`**` A crozier is formed when the tip of the ascogenous hyphae recurves forming a hooked cell. The two nuclei in the penultimate cell of the hypha fuse to form a diploid nucleus. This cell form young ascus.
`**` The diploid nucleus undergo meiotic division to produce four haploid nuclei, which further divide mitotically to form eight nuclei. The nucleus gets organised into 8 ascospores.
`**` The ascospores are found inside a bag-like structure called ascus. Due to the presence of ascus , this group is popularly called "Sac fungi".
`**` Asci gets surrounded by sterile hyphae forming fruit body called ascocarp.
`**` There are 4 types of ascocarps namely Cleistothecium ( Completely closed), Perithecium (Flask shaped with ostiole), Apothecium (Cup shaped and open type) and Pseudothecium .