Introduction of Fungi In Plant Pathology
Fungi are filamentous, multi -cellular organisms, having organized nucleus with nuclear membrane, always lacking of chlorophyll,but presence of cell wall in true fungi and multiplication by production of asexual or sexual spores of vegetative cells.
Vegetative structure of fungi:
• In the true fungi true cell wall is present whether the thallus is a unicellular or a multicellular branching body.
• The branches are hyphae and the entire vegetative body is mycelium.
Reproduction of fungi:
a. Asexual reproduction:
• In asexual reproduction the hyphae cut off minute spores.
• The structure and origin of these spores vary greatly and each types has been given different names i.e. chlamydospores, conidiophores (conidia), in mastigomycotina sporangium, sporangia are formed,
in aquatic forms, sporangia liberate naked protoplasmic bodied, the swamspore or zoospores.
• The conidia may be produced in special structures is pycnidia, sporodochia, acervali in the ascomycotina and deuteromycotina
b. Sexual reproduction:
• Involves two separate gametes.
• The sexual reproduction by union of two morphologically dissimilar gametes is oogamy
(leads to development of simple structure oospores or a complex fruit cleitothecium, perithecium, apothecium).
• In most of higher form of fungi the sexual process involves the union of two similar gamatangia.
This is isogamy (lead to formation of zygospore or zygote).
Common group of plant diseases fungi are:
I. Ustilaginales : Smut fungi
2. Uredinales : Rust fungi
3. Erysiphaceae : Powdery mildews
4. Peronosporaceae : Downy mildews
