Write down the salient features of Ascomycetes.

Explanation

1. Majority of the species live in terrestrial environment, some live in aquatic environments both fresh and marine.
2. The mycelium is well developed, branched with simple septum.
3. Majority of them are saprophytes but few parasites are also known. Eg: Powdery mildew - Erysiphe.
4. Asexual reproduction takes place by fission, budding, oidia, conidia, chlamydospore.
5. Sexual reproduction takes place by the fusion of two compatible nuclei.
6. Plasmogamy is not immediately followed by karyogamy. Instead a dikaryotic condition is prolonged for several generations.
7. A special hyphae called ascogenous hyphae is formed.
8. 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.
9. The diploid nucleus undergo meiotic division to produce four haploid nuclei , which further divide mitotically to form eight nuclei. The nucleus gets organised in to 8 ascospores.
10. The ascospores are found inside a bag like structure called ascus. Due to the presence of ascus, this group is popularly called 'Sac fungi'.

11. Asci gets surrounded by sterile hyphae forming fruit body called ascocarp.
12. There are 4 types of ascocarps namely Ceistothecium (Completelyclosed), Perithecium (Flask shaped with ostiole ), Apothecium (Cup shaped, open type) and Pseudothecium.
Eg: Yeast, Cup Fungi.