Kingdom Fungi

It is a unique kingdom of heterotrophic organisms.

• They show a @@great diversity@@ in morphology and habitat.
• Fungi are cosmopolitan and occur in ==air, water, soil, and on animals and plants.==   * They prefer to grow in warm and humid places.   * Fungi are %%filamentous (Except Yeast).%%     * Their bodies consist of long, slender thread-like structures called @@hyphae and their network@@ @@is known as@@ @@mycelium.@@     * Some hyphae are continuous tubes filled with ^^multinucleated cytoplasm^^ ^^known as^^ ^^coenocytic hyphae.^^
• The cell walls of fungi are composed of $<strong>chitin and polysaccharides</strong>.$

Examples:

• The common %%mushroom%% %%and%% %%toadstools.%%
• ==White spots seen on mustard leaves== are due to a parasitic fungus.
• ^^Yeast is used to make bread and beer. (unicellular fungi)^^
• %%Puccinia causes rusting in wheat.%%
• ==Penicillin== is a source of ==antibiotics.==

Saprophytes:

Most fungi are %%heterotrophic and absorb soluble organic matter%% from dead substrates.

Parasites:

• The fungi are heterotrophic and $<strong>depend on living plants and animals</strong>$.
• They can also live as ^^symbionts^^ – in association with %%algae as lichens%% and with $<strong>roots of higher plants as mycorrhiza.</strong>$

Reproduction:

• Vegetative means – $<strong>fragmentation, fission, and budding.</strong>$
• Asexual reproduction is by spores called ==conidia or sporangiospores or zoospores.==
• Sexual reproduction is by %%oospores, ascospores, and basidiospores%%****.   * The various spores are produced in distinct structures called ^^fruiting bodies.^^   * %%The fusion of protoplasms%% between two motile or non-motile gametes is called ^^plasmogamy.^^     * Fusion of two nuclei called %%karyogamy.%%     * ^^Meiosis^^ in zygotes results in ^^haploid spores.^^     * When a fungus reproduces sexually, two haploid hyphae of compatible mating types come together and fuse.

@@Exception:@@ @@In@@ @@Ascomycetes and Basidiomycetes@@, an intervening dikaryotic stage (two nuclei per cell) occurs which is called a @@dikaryon and the phase is called dikaryophase of fungus.@@

Phycomycetes: \n

• Members of Phycomycetes are found %%in aquatic habitats and on decaying wood in moist and damp places%% or as obligate parasites on plants.
• The mycelium is ^^aseptate and coenocytic.^^   * Asexual reproduction takes place by zoospores (motile) or by aplanospores (non-motile).     * These spores are endogenously produced in $<strong>sporangium.</strong>$   * A zygospore is formed by the fusion of two gametes.     * These gametes are ==similar in morphology (isogamous) or dissimilar (anisogamous or oogamous).==

Examples: Mucor, Rhizopus (the bread mold), and ==Albugo== (the parasitic fungi on mustard).

Ascomycetes:

• They are mostly ==multicellular. (Exception:== ==yeast or Saccharomyces)==
• They are %%saprophytic, decomposers, parasitic or coprophilous.%%
• Mycelium is ^^branched and septate.^^   * The asexual spores are $<strong>conidia</strong>$ produced exogenously on the special mycelium called ==conidiophores.==     * ==Conidia on== ==germination== ==produce== ==mycelium.==   * Sexual spores are called ascospores which are produced endogenously in $<strong>sac-like asci</strong>$.     * These asci are arranged in different types of @@fruiting bodies called ascocarps.@@

Examples: ^^Aspergillus, Claviceps, and Neurospora.^^

Note: Many members like ==morels and truffles are edible and are considered delicacies.==

Basidiomycetes:

• They grow in soil, on logs and tree stumps, and in living plant bodies as parasites.
• The mycelium is $<strong>branched and septate.</strong>$   * The $<strong>asexual spores are generally not found</strong>, but$ $<strong>vegetative reproduction by fragmentation is common.</strong>$     * The ==sex organs are absent,== but plasmogamy is brought about by the fusion of two vegetative or somatic cells of different strains or genotypes.       * The resultant structure is ==dikaryotic== which ultimately gives rise to %%basidium.%%     * Karyogamy and meiosis take place in the basidium producing @@four basidiospores.@@
• The basidiospores are exogenously produced on the basidium.   * The basidia are arranged in $<strong>fruiting bodies called basidiocarps.</strong>$

Examples: %%Agaricus (mushroom), Ustilago (smut), and Puccinia (rust fungus).%%

Deuteromycetes:

• They are commonly known as $<strong>imperfect fungi because only the asexual or vegetative phases of these fungi are found.</strong>$
• Once perfect (sexual) stages of members of Deuteromycetes were discovered they were often moved to ascomycetes and basidiomycetes.   * The Deuteromycetes reproduce only by @@asexual spores known as conidia.@@     * The mycelium is ^^septate and branched.^^   * Some members are saprophytes or parasites while a large number of them are $<strong>decomposers</strong>$ $of litter and help in$ $<strong>mineral cycling</strong>.$

Examples: %%Alternaria, Colletotrichum, and Trichoderma%%.

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