The Kingdom : Fungi

The fungi constitute a unique kingdom of heterotrophic organisms and fungi show a great diversity in morphology and habitat. The fungi can be seen on a moist bread and rotten fruits. The common mushroom and toadstools are also fungi.

The white spots on mustard leaves are due to a parasitic fungus.

There are some unicellular fungi yeast are used to make bread and beer, the wheat rust-causing Puccinia cause diseases, some are the source of antibiotics like Penicillium.

Fungi are cosmopolitan and occur in air, water, soil and on animals and plants.

They prefer to grow in warm and humid places. Food we keep in the refrigerator to prevent food from going bad due to bacterial or fungal infections.

The fungi are filamentous except yeasts (which are unicellular). Their bodies consist of long, slender thread-like structures called hyphae and network of hyphae is known as mycelium.

some hyphae are continuous tubes filled with multinucleated cytoplasm – these are called coenocytic hyphae. Others have septae or cross walls in their hyphae.

The cell walls of fungi are composed of chitin and polysaccharides. The most fungi are heterotrophic and absorb soluble organic matter from dead substrates and hence are called saprophytes.

The reproduction in fungi can take place by vegetative means fragmentation, fission and budding.

The asexual reproduction is by spores called conidia or sporangiospores or zoospores and sexual reproduction is by oospores, ascospores and basidiospores. The various spores are produced in distinct structures called fruiting bodies.

The sexual cycle involves the three steps:

a. Fusion of protoplasms between two motile or non-motile gametes called plasmogamy.

b. Fusion of two nuclei called karyogamy.

c. Meiosis in zygote resulting in haploid spores.