Q.Give a detailed comparative account of the four classes of Kingdom Fungi (Phycomycetes, Ascomycetes, Basidiomycetes and Deuteromycetes) with respect to their hyphal structure, mode of spore formation and reproduction, giving one example of each class.
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Start your 14-day free trial to unlock the full solution →The four classes of Kingdom Fungi are distinguished chiefly by whether their hyphae are septate or aseptate, and by the specific asexual and sexual spore-forming structures each class uses.
Phycomycetes. Found predominantly in aquatic habitats and on decaying wood in moist places, or as obligate plant parasites. Their mycelium is aseptate and coenocytic -- a continuous, multinucleate tube without cross-walls. Asexual reproduction occurs via zoospores (motile) or aplanospores (non-motile), produced inside a sporangium; sexual reproduction produces a thick-walled zygospore through gamete fusion. Example: Rhizopus (bread mould) and Mucor.
Ascomycetes ('sac fungi'). Largely multicellular (except unicellular yeast, Saccharomyces), and saprophytic, decomposer, parasitic or coprophilous. Mycelium is branched and septate. Asexual conidia are produced exogenously on conidiophores; sexual ascospores are produced endogenously within a sac-like ascus, arranged in fruiting bodies (ascocarps). Example: Aspergillus, along with Claviceps, Penicillium and Neurospora.
Basidiomycetes. Includes mushrooms, bracket fungi, puffballs, and important plant parasites (rusts, smuts). Grows in soil, on logs, and as parasites on living plants. Mycelium is branched and septate; vegetative reproduction is mainly by fragmentation, and this class lacks asexual spores altogether. Sexual reproduction (following internal plasmogamy and karyogamy) produces club-shaped basidia, on which basidiospores are formed exogenously (typically four per basidium), housed in fruiting bodies (basidiocarps). Example: Agaricus (edible mushroom), Ustilago (smut) and Puccinia (rust).
Deuteromycetes ('Fungi Imperfecti'). So named because only their asexual (vegetative) phase is known; a species is reclassified into Ascomycetes or Basidiomycetes once its sexual stage is eventually discovered. Mycelium is septate and branched. Reproduction is only by asexual conidia, with no known sexual phase, and members are typically saprophytic or parasitic. Example: Alternaria, Trichoderma and Colletotrichum. …
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