KINGDOM FINGI

KINGDOM FUNGI

General Characteristics

1. Fungi are achlorophyllous, spore bearing and non-vascular organisms.
2. Fungal cell wall is made up of chitin-the fungal cellulose.
3. They are usually filamentous with branched somatic bodies.
4. They are heterotrophic and reproduce generally by spores.
5. They can be parasitic, saprophytic or symbiotic.
6. They occur in long lasting beneficial association with the roots of gymnosperms. This association is called mycorrhiza.
7. They range from unicellular forms to thread like structures known as mycelium.
8. The interconnected filaments of mycelia are called hyphae.
9. Each hypha is bounded by a chitinous cell wall.
10. Multinucleate forms are known as coenocytic.

Cell Structure

1. Fungal cell is eukaryotic with a chitinous cell wall.
2. Hyphal or fungal cell wall encloses the protoplast which is differentiated into plasma membrane, cytoplasm and nucleus/ei.
3. Reserve food is in the form of glycogen and lipid globules.
4. Membranous vesicles called lomasomes are found attached to the cell membrane.
5. Cytoplasm is colourless and vacuolated.
6. Fungal hyphae may be septate or aseptate with one, two or more nuclei.
7. In case of aseptate hyphae the the cross wals are not formed after nuclear divisions and hence such forms are multinucleated or coenocytic.
8. In case of septate hyphae the cross walls are laid down after nuclear divisions and such forms are called acoenocytic forms.
9. Septa are generally perforated with pores, which can be simple or dolipores.
10. Dolipores are barrel shaped with swollen edges.

Stages in the development of  a branched hypha

Phases in the life cycle of Fungi

Reproduction in Fungi

1. Vegetative Reproduction

(a)    Fragmentation- Vegetative hyphae get broken into fragments accidentally and the fragments develop into new mycelia eg. Rhizopus, Mucor.

(b)   Fission- In this case, the parent cell splits into two daughter cells by constriction eg. Yeasts.

(c)    Budding- A small outgrowth appears in the vegetative cell and enlarges in size eg. Yeasts.

(d)   Sclerotia- These are more or less rounded,cushion-like cylindrical or irregular structures. They grow under favourable conditions to produce mycelia eg. Claviceps.

(e)    Rhizomorphs- They are rope like twisted subterranean masses of several interwoven hyphae with well-defined apical growing point.

2. Asexual Reproduction

  

 

3. Sexual Reproduction

Classification of Fungi

S.No.	Group	General Features	Examples	Diagrams
	Phycomycetes (Algal fungi)	Mycelium is coenocytic. Wall of hyphae contains cellulose. Asexual reproduction involves formation of sporangia, which produce zoospores, aplanospores. Sexual reproduction is by gametangial contact. Gametes are usually nonflagellete. Ptroduct of sexual reproduction is oospore. Hence, they are also called as oomycetes. They may be parasites or saprophytes.	Phytophthora, Albugo,Pythium
	Zygomycetes (Conjugation Fungi)	Mostly saprophytes, some may be parasites on plants and animals. Cell wall is mainly composed of fungal chitin. Mycelium is well developed, profusely branched, filamentous and coenocytic. Asexual reproduction takes place by sporangiospores, aplanospores or by conidia. Sexual reproduction takes place by conjugation and hence are called conjugation fungi. Sexual reproduction produces a resting diploid zygospore. Zygospore produces germ sporangiophore which bears terminal germ sporangium, which in turn produces meiospores called germ spores.	Rhizopus, Mucor
	Ascomycetes (Sac Fungi)	Saprophytes or parasites. Are haploid fungi and their mycelium is composed of septate hyphae. Cell wall is made up of fungal cellulose. Motile structures are absent throughout their life cycle. Most distinctive feature of this group is the formation of sac like structure, the ascus, in which eight ascospores are produced. Asexual reproduction occurs by oidia, conidia nad chlamydospores. Sexual reproduction occurs by gametangial copulation, gametangial contact, spermatisation and somatogamy. Fertilisation involves plasmogamy and karyogamy.	Saccharomyces, Penicillium, Neurospora
	Basidiomycetes (Club Fungi)	The mycelium is perennial, septate and multicellular composed of branched hyphae. Mycelia are of two type- primary and secondary. Primary mycelia develop by the germination of basidiospores and its cells are monokaryotic. Primary mycelium is short and multiplies by oidia or conidia. Motile structures are all together absent. Sexual reproduction occurs between + and – strains in three steps- plasmogamy, karyogamy and meiosis. Secondary mycelium is long lived and consists of profusely branched, filamentous hyphae which are septate and binucleate. Septa consist of dolipores. Secondary mycelia multiply by chlamydospores, ascidiospores etc. They penetrate into the soil or wood by sclerotia or rhizomorphs. Karyogamy and meiosis takes place in the basidia.	Agaricus campestris, Puccinia, Amanita
	Deuteromycetes (Fungi Imperfectii)	They are saprophytes or parasites. Mycelia consist of septate and branched hyphae. Septa are perforated and multinucleate. Reproduction is by conidia, oidia or chlamydospores. Sexual reproduction is absent	Alternaria solani, Fusarium