Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 14 Fungi Importance of Fungi Together with Heterotrophic bacteria Ecological decomposers Decomposing fruit- Rhizopus Root-rot fungus- white mycelial causes disease in living trees Acts as decomposers on dead plants Root rot Ouch!!! Fungi • Composed of Hyphae • Heterotrophic absorbers Characteristics of Fungi • Composed of Hyphae Fungal filaments= “Cobwebby” strands of subterranean “white stuff” Mycelium Fungi form important symbiotic relationships • 80% of all vascular plants species from mutually beneficial associations called mycorrhizae between roots and fungi • Plant nutrition • Lichens form symbiotic relationship with fungi, algal, or cyanobacterial cells • Fungi and insects • Endophytes- fungi live in plants produce toxic that protect host Four phyla of fungi • Chytridiomycota • Zygomycota • Ascomycota next week lecture • Basidiomycota next week lecture Chars of Fungi • All have cell wall • Cell wall composed of polysaccharide- chitin • Chitin more resistant to microbial degradation than cellulose All Fungi Heterotrophic Absorbers • Unable to engulf small microorganisms • Secrete enzymes and absorb smaller molecules •Absorb food mostly at or near the growing tips of their hyphae Fungi obtain their food • Either as Saprophytes or • As mutualistic symbionts Some • Obtain energy through fermenation producing ethyl alcohol from glucose (i.e. yeast) Fungi Store energy • Polysaccharide • Glycogen • Lipids Fungi reproduce both sexually and asexually • Reproduce through the formation of spores that are produced sexually or asexually • Most are nonmotile spores • Some are dry and small and airborne • Some are slimy and stick to the bodies of insects and other arthropods • Some propel into airphototropism Common method of asexual reproduction in fungi • By means of spores • Either produced in sporangia – The sporangium is a saclike structure, the entire contents of which are converted into one or more spores Asexual reproduction • Or • Hyphal cells called conidiogenous cells – Spores produced by conidiogenous cells occur singly or in chains called conidia Asexual repro • Some Reproduce by fragmentation of their hyphae Sexual reproduction • Three distinct phases • First two are phases of fertilization (syngamy) – Plasmogamy- the fusion of protoplasts – Karyogamy- the fusion of nuclei (some don’t fuse forming a dikaryon) Divide by mitosis Give rise to gametes by differentiation gametangia 4 Spores The last phase is meiosis • Sexual reproduction results in the formation of specialized spores such as zygospores, ascospores, basidiospores. Zygospores • Zygospores • Asexual and sexual reproduction (by means of haploid spores) • Sexually producing zygospores require two compatible species Zygomycetes: Phylum Zygomycota • Live on decaying plant and animal matter in soil • Some are parasites of plants, insects or small soil animals • Others form symbiotic relationshipsendomycorrhizea- with plants occasionally cause infection in animals • Rhizopus stolonifer- best known zygomycetes Life cycle of Rhizopus stolonifer Gametangia the gamete producing structures are in the Process of producing a zygospore Zygospore develops within the thick walled zygosporangium