Presentation on theme: "Prof. Khaled H. Abu-Elteen"— Presentation transcript:
1 Prof. Khaled H. Abu-Elteen Fungal Life CyclesProf. Khaled H. Abu-Elteen
2 Basic fungal life cycle 1. Zygotic - haploid phase is dominantfig. 13.5b
3 Basic fungal life cycle 2. Fertilization doesn’t happen all at oncePlasmogamy - fusion of cytoplasmKaryogamy - fusion of nuclei (gametes)heterokaryoticdikaryoticfig. 31.2
4 3. Yeast for brewing and baking: Saccharomyces cerevisiae
5 B. Zygomycota 1. No dikaryotic growth 2. Both sexual and asexual sporangia
6 C. Ascomycota - Life cycle 1. Dikaryotic growth2. Fruiting body: ascocarp3. Fertile layer with asci4. Eight ascospores perascus (sac)5. Asexual reproductionvia conidia
7 D. Basidiomycota - Life cycle 1. Dikaryotic growth2. Fruiting body: basidiocarp3. Fertile layer on gillswith basidia (“clubs”)4. Four spores perbasidium5. Asexual reproductionis rare
8 D. Basidiomycota - structure 2. Fruiting body: basidiocarp3. Fertile layer on gillswith basidia (“clubs”)4. Four spores perbasidium
9 E. Deuteromycota - “fungi imperfecti” 1. Not a true phylum (not a natural group): polyphyletic2. Fungi with no known sexual reproduction3. Asexual reproduction by conidia
10 III. Fungal Mutualisms Definitions: Symbiosis - 2 organisms living together in intimate physical contactMutualism - both organisms benefit from the relationshipParasitism - one benefits, one losesCommensalism - one benefits, other not affected
11 III. Fungal Mutualisms Questions: 1. Definition of mutualism vs. symbiosis2. What fungal and photosynthetic partners are involved?3. What is the “currency” of the mutualism? How do the partners benefit?4. What is the structure and/or morphology of the organismal interaction?5. What is the ecological importance?
12 FUNGAL LIFE CYCLES ASEXUAL HAPLOID HAPLOID WITH RESTRICTED DIPLOID HAPLOID-DIKARYOTICDIKARYOTICHAPLOID-DIPLOIDDIPLOID
13 MITOSPORES Result from mitosis and cell division No change in nuclear ploidyUsually produced in great quantitiesResistance to unfavorable environmental conditions variesAre important in dispersal
14 MITOSPORES motile - zoospores non-motile - produced from hyphae - conidianon-motile - produced from sporangia - sporangiospores
15 MEIOSPORES Result from meiosis Are haploid Are genetically different from parent hyphaeMay serve as a resistant stageAre important in dispersal
16 CHLAMYDOSPORES Nuclear ploidy same as parent cell Formed from a vegetative cell or cellsShape may reflect cell shapeWall may become thickened and dark in colorAre resistant to unfavorable environmental conditions
19 GERMINATION PROCESSWater content increases; spore swells; enzymes go into solution.Vacuolation increases.Endoplasmic reticulum & other organelles increaseRespiration increases & mitochondria enlarge and form more cristae.
21 GERMINATION PROCESS Vesicles involved in wall synthesis appear. Lipids disappear as they are used up as an energy source.An opening on the spore wall appears or the plug in a germ pore is removed.A hyphal tube, called the germ tube, emerges from the opening or pore.
23 SPORE CHARACTERISTICS Low water content.Large quantities of storage compounds.Wall structure different from parent hyphae.Wall differentiation (pitted, warted, spinulose, gelatinous sheaths, appendages).All cellular organelles are present except a vacuole.
24 General Fungi Life Cycle Dikaryotic if “hetero” is 2 haploid nuclei/cellNote mostly haploid or heterokaryoticDiploid only transient in most fungal speciesMitosis products
25 Molds are asexually reproducing (i. e Molds are asexually reproducing (i.e., spore-forming), filamentous fungi (i.e., not yeasts)MoldsThis is the mold Penicillium from which the antibiotic penicillin is isolated
26 Yeasts tend to inhabit very moist habitats, which includes plant and animal tissues Yeasts are single-celled fungiYeastsYeasts tend to grow asexually (no spores)Yeasts as a taxon would be polyphyletic
28 Ascomycetes: Sac Fungi Asexually produced reproductive cells are called conidiaAscomycete form asci, which are linear sacs containing eight ascosporesHave extended dikaryotic stageAscomycetes: Sac FungiIn many the ascomycetes the asci are arrayed into fruiting bodies called ascocarpsMany ascomycetes are important plant saprobes: they decompose dead plant material
29 Asci with AscosporesSordaria macrospora is a filamentous ascomycete which is closely related to Neurospora crassa. But in contrast to Neurospora, Sordaria is homothallic, which means that a single strain produces fruiting bodies without the need for a partner of opposite mating type. The life cycle of S. macrospora is shown in the picture. It starts with an ascospore which germinates and produces a mycelium. Within a week, fruiting bodies develop in which asci are produced that contain eight ascospores each. The ascospores are ejected from the fruiting body and the cycle starts again.
30 Ascomycetes: Sac Fungi These are not mushrooms!!!They are ascocarpsAscomycetes: Sac Fungi
32 Basidiomycetes: Club Fungi Both mushrooms and shelf fungi are club fungiClub fungi are not limited to just mushrooms and shelf fungi, howeverBasidiocarps produce basidiosporesBasidiomycetes: Club FungiLike sac fungi, have a long-lived dikaryotic stageBest lignin decomposers of all fungi
33 Mushrooms, etc., are basidiocarps “By concentrating growth in the hyphae of mushrooms, a basidiomycete mycelium can quickly erect its fruiting structures in just a few hours”Basidiocarps
34 Basidicarps and Basidia Basidia with basidiospores