Fungi Lecture Notes PDF

Myco = Fungus logy = Study  1- General Characters Eukaryotic Organisms (i.e true nucleus surrounded by nuclear membrane) Non-motile except few fungi Vegetative body (somatic body ) may be: Unicellular Filamentous (yeast fungi)...

Myco = Fungus logy = Study  1- General Characters Eukaryotic Organisms (i.e true nucleus surrounded by nuclear membrane) Non-motile except few fungi Vegetative body (somatic body ) may be: Unicellular Filamentous (yeast fungi) Non-Septated Septated Coenocytic  Like plants, have alternation of generation cell wall similar in structure of plant but differ in chemical composition Plant C.W. Cellulose + lignin Fungi C.W. Chitin Fungi are Heterotrophic organisms (lack chlorophyll) Growth by apical elongation of hyphal tip Food stored as glycogen but plant as starch Cell membrane in animal cholesterol in Fungi ergosterol  Economic Importance Beneficial Harmful Industrial uses Cause human, animal, plant baking & brewing (by Yeast) disease directly or their toxins Antibiotics production ( penicillin) Cause rot of food Production of Steroids and Hormones Can destroy manufactured products. making Cheeses Source of organic compost Source of food like mushrooms, enzymes, acids and biofuels Source of vitamins (yeast source for vitamin. B-complex) In nature They participate in nutrient recycling. Produce many enzymes to decay complex animal and plant materials. Make symbiotic association with plants which improve their functions in absorbing water and nutrients(Mycorrhizae)  2- Nutrition in fungi Saprophytes Parasites Symbiotic Saprophytes : 1- use non - living organic materials 2- important in recycling C,N and essential mineral nutrients  Parasites : 1- use organic materials from living organisms , causing diseases to them 2- they have a wide range of hosts as diatoms , fungi , plants ,animals , human. Symbiotic : 1- fungi that have a beneficial symbiotic relationship with other living organisms Ex : Mycorrhizae Lichens Commensalism  Reproduction Types of reproduction Sexual Asexual a. Sexual: - Involve the fusion (union) of two compatible nuclei with a subsequent meiotic division - All sexual fungal life cycles consists of : plasmogamy karyogamy meiosis Cell fusion Nuclear fusion 2N reduced to 1N (fusion of two protoplasm of two gametes) (fusion of two nuclei of two gametes) (formation of haploid spores)  - All sexual fungal life cycles consists of : meiosis plasmogamy karyogamy Cell fusion Nuclear fusion 2N reduced to 1N (fusion of two protoplasm of two gametes) (fusion of two nuclei of two gametes) (formation of haploid spores)  Meiosis 1n Haploid number of chromosomes 2n Diploid number of chromosomes Then Zygot develops into Different types of sexual spores: Ascospores (Ascomycetes) Basidiospores(Basidiomycetes) Zygospores (Zygomycetes) Oospore (Oomycetes)  b. Asexual: 1. Fragmentation (Filamentous fungi) : The mycelium breaks up into fragments (arthrospores), each fragment germinate into a new individual under favorable conditions  2. Fission: In unicellular true fungi (Yeast), the vegetative cell splits into two equal daughter cells 3. Budding: In unicellular true fungi (Yeast) The vegetative cell produces a small out growth (bud) which is finally separated from the mother cell and form a new cell  4. Spore formation According to manner by which spores are borne on the mycelium, there are two types: Sporangiospores Conidia  Sporangiospores: Asexual spores produced internally in a sac like structure called sporangium, borne on specialized hyphae called sporangiophore Sporangiospores may be: motile or non motile Motile Called zoospores Non motile Called a planospores Are disseminated by wind current  Conidia: Asexual non motile spores produced externally on a special hyphae called conidiophore Conidia may formed singly or in chain Conidiophores may be free from each other or aggregated to form the following compound structures pycnidium acervulus sporodocium General Fungi Reproduction Cycles (Alternation of generation) Key Heterokaryotic Haploid (n) stage Heterokaryotic (n + n) Fusion of nuclei (unfused nuclei) Diploid (2n) Fusion of cytoplasm Zygote Spore-producing (2n) structures Sexual reproduction Meiosis Spores (n) Asexual Mycelium reproduction Spore-producing structures Germination Germination Spores (n)  Fungi are classified as following: kingdom: protozoa kingdom: Eumycota (Slime moulds) (True Moulds) The vegetative kingdom: chromista Produce non- motile phase is plasmodium Produce motile spores(aplanospores) (ameoboid structure) spores(zoospores) Vegetative body is Slimy, naked (no cell Vegetative body is mycelium wall), multinucleate mycelium Classified according mass of protoplasm, Oomycetes to the method of move by (produce Oospore) sexual reproduction pseudopodia. Zygomycetes Ascomycetes Basidiomycetes Reproductive part: spores  Fungal cell structure Fungi are eukaryotes and have a complex cellular organization. In eukaryotes, fungal cells contain a membrane-bound nucleus where the DNA is wrapping around histone proteins.  The fungal cell wall Both the structure and composition of the fungal cell wall have unique characteristics: The polysaccharide β(1,4) N-acetyle-glucose-amin, generally known as chitin, is a unique cell wall component of the fungi, but the amount of chitin of cell walls of different groups may differ strikingly:  Baker’s yeast has only a small amount (1% of cell wall dry weight) of chitin in its cell wall. In some groups (e.g. in some zygomycetes) the chitin is partially deacetylized by an enzyme (chitin deacetylase) and so the cell wall will contain chitosan (deacetylized chitin).  The Oomycetes have also cell walls and some species have a small amount of chitin in their walls, but the vast majority has no chitin at all. On the other hand, their cell walls contain cellulose, a β(1,4) glucan, which is never present in true fungi.  The fungal cell walls contain polysaccharides mainly β (1,3) and β(1,6) glucans synthesized by the transmembrane glucan synthase enzymes. Most proteins of the cell wall are present in glycolized form (even 90% of the proteins could be glycolized). A majority of the glycoproteins are mannans or mannoproteins, the proteins being connected by mannose. Some proteins are anchored in the cell membrane and play crucial roles in cell wall integrity.  The fungal cell membrane special fungal sterols affect membrane fluidity of the fungi. The most widely known are the ergosterols. ❑Its function is to protect the integrity of the interior of the cell by allowing certain substances into the cell while keeping other substances out. ❑The special membrane components have great importance in antifungal therapy; several fungicides target those molecules or their synthesis pathway. For example, the polyens target the ergosterols and disintegrate the membrane, whereas azols target the synthesis pathway of ergosterols.  Cytoplasmic Inclusions 1. Vacuoles: Vacuoles are found in the old cells of hyphae. The end of hyphal tip of young hyphae lacks vacuole. With the age, the vacuoles coalesce. Vacuoles are surrounded by a membrane known as tonoplast. Function of The vacuole: 1. degradative processes. 2. primary storage site for certain small molecules and biosynthetic. precursors such as basic amino acids and polyphosphate. 3. plays a role in osmoregulation.  2: Endoplasmic Reticulum (ER): An organelle that is responsible for the accurate folding, post-translational modification and final assembly of the cellular protein. In multinucleate hyphae the nuclei may be connected by endoplasmic reticulum. 3:The nucleus The cytoplasm contains one, two or more globose or spherical nuclei of about 1-3 p.m diameter (1x10-12) meter. Nucleus consists of a bilayered porous nuclear envelope that encloses the chromosomes and nucleolus. The chromosome consists of DNA and a few basic proteins called histones. The nuclear pores permit to interchange the materials between the cytoplasm and nucleus. 4: Mitochondria ❑ The function of the mitochondria in fungal cells is to convert simple carbohydrates (glucose) to a complex energy-storing molecule called adenosine triphisphate (or ATP) through the process of cellular respiration. ❑ ATP is used not only in growth of individual cells, but also in controlling cell division. They aid in protein regulation. ❑ Mitochondria produce ATP, ATP powers proteins, proteins aid in growth, and growth helps the fungus survive. ❑ The inner infoldings form parallel flat plates of irregular tubules called cristae 5: Golgi Apparatus or Dictyosomes: Golgi apparatus consists of stacks of folded membranes functioning in secretion. Proteins synthesized in the ER are packaged into vesicles, which then fuse with the Golgi apparatus Ecological Groups of Fungi  Fungi are heterotrophic organisms. The modes of heterotrophic life in fungi are categorized into: 1. Saprobic: living at the expense of dead organic matter. 2. Parasitic: living at the expense of another host organism (algae, plants, fungi, animals); Biotrophic if the host is colonized while fully alive. Necrotrophic if the host is first killed and then fully colonized. 3. Symbiotic: a mutual relationship that benefits both the fungus and its partner(s). 1:Symbionts and Endophytes Fungi living on the exterior of their hosts are called epiphytes. Those living within host tissue, which are termed endophytes. A: Endophytes: can protect host plants from insect herbivory and from other fungal pathogens used as bioregulators to induce resistance against diseases. biological control agents against certain pathogens and undesirable weeds.  Methods for isolation 1:Tissue pieces are sterilized using the following protocol: 60 s in 70% ethanol 2-5 min in NaOCl (1-3 %; depending on tissue type) and again 60 s in 70% ethanol (to remove the NaCOl). 2: Tissue samples are plated on PDA amended with streptomycin (1 mL/L) and incubated at 25 ᵒC. 3: Emerging fungal colonies must be hyphal-tipped, and transferred to PDA slants for further identification. B: Symbionts Lichens Lichen is a beneficial mutualistic association between a fungus and an alga. Mycobiont: the fungal partner in lichen. Photobiont: the photosynthetic partner in a lichen; either a green alga or cyanobacterium. Characters of Lichens Worldwide distribution, often in the most extreme environments, Arctic, Antarctic, deserts and all other habitats. Occur on soil, plants, animals, rocks, decorate tombstones, buildings, etc. Rare in polluted areas - intolerant of industrial pollutants, especially sulfur dioxide. Mycobiont usually takes up about 90% of the thallus and is usually an ascomycete (most are inoperculate discomycetes) or occasionally a basidiomycete (eg. Omphalina, Multiclavula). Photobiont may be a green alga, cyanobacterium or both. Both the algae and cyanobacteria fix carbon and the cyanobacteria fix nitrogen. Advantages to the alga: Mechanical protection from injury & high light by being tightly enveloped by hyphae. Improved water relations and resistance to desiccation. Provides minerals. Advantages to the fungus: Organic nutrients (carbon & nitrogen) provided by photobiont. Lichenized fungi have greater longevity. Most lichenized fungi are never found free-living in nature. Structure of lichens – Cortex (upper and/or lower). – Medulla (fungal layer). – Algal layer. Types of lichens: Stratified lichen: algal cells are not distributed through lichen. Non Stratified lichen: algal cells are distributed through Uses of Lichens Food Dyes Essential oils for perfumes, soaps Bioactive compounds (antiviral, antibacterial) Nesting/bedding material Poisons  Reproduction of Lichens: Sexual spores (ascospores & basidiospores). Conidia Ecological Groups of Fungi  Fungi are heterotrophic organisms. The modes of heterotrophic life in fungi are categorized into: 1. Saprobic: living at the expense of dead organic matter. 2. Parasitic: living at the expense of another host organism (algae, plants, fungi, animals); Biotrophic if the host is colonized while fully alive. Necrotrophic if the host is first killed and then fully colonized. 3. Symbiotic: a mutual relationship that benefits both the fungus and its partner(s). 1:Symbionts and Endophytes Fungi living on the exterior of their hosts are called epiphytes. Those living within host tissue, which are termed endophytes. A: Endophytes: can protect host plants from insect herbivory and from other fungal pathogens  used as bioregulators to induce resistance against diseases.  biological control agents against certain pathogens and undesirable weeds.  Methods for isolation 1:Tissue pieces are sterilized using the following protocol: 60 s in 70% ethanol 2-5 min in NaOCl (1-3 %; depending on tissue type) and again 60 s in 70% ethanol (to remove the NaCOl). 2: Tissue samples are plated on PDA amended with streptomycin (1 mL/L) and incubated at 25 ᵒC. 3: Emerging fungal colonies must be hyphal-tipped, and transferred to PDA slants for further identification. B: Symbionts Lichens Lichen is a beneficial mutualistic association between a fungus and an alga. Mycobiont: the fungal partner in lichen. Photobiont: the photosynthetic partner in a lichen; either a green alga or cyanobacterium. Characters of Lichens Worldwide distribution, often in the most extreme environments, Arctic, Antarctic, deserts and all other habitats. Occur on soil, plants, animals, rocks, decorate tombstones, buildings, etc. Rare in polluted areas - intolerant of industrial pollutants, especially sulfur dioxide. Mycobiont usually takes up about 90% of the thallus and is usually an ascomycete (most are inoperculate discomycetes) or occasionally a basidiomycete (eg. Omphalina, Multiclavula). Photobiont may be a green alga, cyanobacterium or both. Both the algae and cyanobacteria fix carbon and the cyanobacteria fix nitrogen. Advantages to the alga: Mechanical protection from injury & high light by being tightly enveloped by hyphae. Improved water relations and resistance to desiccation. Provides minerals. Advantages to the fungus: Organic nutrients (carbon & nitrogen) provided by photobiont. Lichenized fungi have greater longevity. Most lichenized fungi are never found free- living in nature. Structure of lichens – Cortex (upper and/or lower). – Medulla (fungal layer). – Algal layer. Types of lichens: Stratified lichen: algal cells are not distributed through lichen. Non Stratified lichen: algal cells are distributed through Uses of Lichens Food Dyes Essential oils for perfumes, soaps Bioactive compounds (antiviral, antibacterial) Nesting/bedding material Poisons  Reproduction of Lichens: Sexual spores (ascospores & basidiospores). Conidia Mycorrhizae Definition Types Functions  Symbiotic association between a fungus & the root of vascular plants. The roots of 95% of all kinds of vascular plants are involved in mycorrhizae. It's believed that the symbiotic association of plant roots & fungi led to our modern vascular plant.  Types of mycorrhizae 1-Ectomycorrhizae 2-ectendomycorrhizae 3-endomycorrhizae Arbuscular mycorrhizae(AM) Ericoid endomycorrhizae Orchid endomycorrhizae  1-Ectomycorrhizae form a sheath (covering the root tip) the fungus grows between the plants cell producing the harting net (extensive network of intercellular hyphae between epidermal& cortical cells) Septate fungi ( Ascomycetes )  2-Ectendomycorrhizae different from Ectomycorrhizae in that some hyphae actually penetrate into the root cells Septate fungi ( Basidomycetes )  3-Endomycorrhizae A) Arbuscular mycorrhizae (AM) the hyphae enter the plant cells, producing vesicles(which are swollen spherical or (oval) structures or arbuscules (finely dichotomously branching hyphae invaginations) ; to increase surface area between hyphae & cytoplasm of the cell where nutrients exchange (major site of nutrient exchange between fungus and plant) Non-septate fungi ( zygomycota )  B)Ericoid endomycorrhizae the fungus penetrate the plant cells. consisting of dense coils of hyphae in the root cells. Septate fungi. (Ascomycetes ) Ericoids : “are trees such as tea & blue berry”.  C) Orchid endomycorrhizae Hyphae penetrate cells of embryo & form coils called pelctons. Septate fungi (Basidomycetes ) Orchid : “plants which produce flowers like orchids & vanilla (flowering monocot plants)”.  Functions of mycorrhizae :- Mycorrhizae can increase the plant's competitiveness depending on the environment of the plant improving plant growth. Wet environment :- they increase the availability of nutrients , especially phosphate Arid environment:-The mycorrhizae aid in water uptake, allowing the increase in transpiration rate in comparison with non-mycorrhizal plants Mycorrhization Helper Bacteria These are symbiotic bacteria trapped within Mycorrhizal of fungi they can found in cytoplasm of Ectomycorrhizae and also Arbuscular mycorrhizea. Bacteria play a role in the development of the Mycorrhizal relationships. The main function of bacterial symbionts in ectomycorrizal fungus is that these trapped bacteria contribute to the (N) metabolism by assisting with the synthesis of essential amino acid. 2: SOIL FUNGI  Fungi are usually the most abundant component of the soil microfloran in terms of biomass, though their numbers in dilution plates are lower than those of bacteria. Fungi are the major microbial decomposers in the soil, particularly in forest soils, mainly participating in the decomposition of cellulose, chitin and lignin in the upper soil layers.  Occurrence of fungi in soil Most of them are saprotrophs (soil-borne fungi). Many of which occur with increased densities around roots (the rhizosphere).  Some of them may be parasitic or semiparasitic on plant roots (root-inhabiting fungi). Some aquatic zoosporic fungi can also occur in soils. Fungi live most of the time in the soil in a dormant condition. Fungi are present in soil as : mycelium. (sexual or asexual) spores. chlamydospores sclerotial bodies Isolation technique A: Non selective technique 1: The dilution plate technique The Dilution plate technique (Johnson & Curl 1972) is the best known and most frequently used quantitative procedure.  Procedure Soil diluted with sterile water 1:10 (w/v). sometimes with 0.1% Na-pyrophosphate or 0.15% water agar to obtain more stable suspensions. suspension is shaken by hand or mechanically for 10-20 min. the suspension is further diluted in steps of 10 times; 1 mL aliquots of the suspension 10*-4 to 10*-6  Petri dishes and mixed with 10 mL undercooled agar (ca. 45C) with the addition of antibiotics against bacteria 0.1 mL can be pipetted into agar plates and distributed evenly with a glass rod. After incubation, plates of the concentration showing 10-30 colonies are selected and used for isolation. 2: Warcup's soil plates: Larger soil particles have a tendency to sediment quickly in the soil suspension and to be lost during the dilution procedure; therefore species with large hyphal complexes have little chance of being isolated with the dilution plate technique procedure: 1. 1 mL of an antibiotic solution (10 times the final concentration) is pipetted into sterile Petri dishes. 2. a very small amount of a soil sample (less than 1 mg) is dispersed in this liquid. 3. undercooled malt agar (1%) is poured into the dish and mixed thoroughly with the antibiotic-soil suspension. 3.Soil washing technique: The first two techniques mainly facilitate the isolation of species present as spores. In order to shift the balance in favour of mycelial propagules in the soil, washing techniques have been devised, by which most of the spores are removed.  B: Selective techniques 1. hair bait technique: For the selective isolation of dermatophytes and other kerationophilic fungi.  Sterile hairs of horse, sheep or man (children) are incubated in Petri dishes above moist soil.  Colonizing fungi are transferred onto Sabouraud-glucose agar or 4% malt agar containing 500 ppm actidione and 50 ppm chloramphenicol. 2: Cellulolytic fungi:  thay are easily baited with pieces or strips of cellophane.  which are buried in the soil for several days, then washed and plated on agar.  3: Water Molds A number of zoosporic fungi live permanently in water or need water in some stages of their life cycle. They generally have motile plano- (zoo-) spores and sometimes motile (plano-) gametes. Aquatic hyphomycetes can also be found on terrestrial substrata and is not exclusively aquatic. Aquatic hyphomycetes often called "Ingoldian fungi”. because Ingold (Ingold 1942, 1975) was one of the first to study them extensively.  Isolation of aquatic fungi Zoospores are caught on baiting substrata placed in a thin layer of water in Petri dish. The most widely used substratum for this purpose is hemp-seed. numerous other baits are in use, some of them are specialized substrates for certain groups of fungi Before use baits are usually boiled for 10 min in water. Baits Range of fungi Hemp-seed (Cannabis sativa) Very broad Seeds of corn (Zea mays) or Argostis alba Various groups Grass blades (Argostis, Paspalum a.o.) Pythium Pollen grains (Pinus) Chytridiales (Rhizophydium) Cellophane Cellulose-decomposing Chytrids (Rhizophlyctis) Dead insects (flies, ant, pupae), shrimp skeleton Various groups, mainly Saprolegniales  4:Fungi on seeds Several methods are in use to discover and isolate pathogenic and saprophytic fungi from seeds: the fungal flora of seeds can be obtained by placing them in Petri dishes on water agar or sterile, moistened filter paper. Superficial fungi develop within a couple of days and are isolated. internal colonizers develop after superficial disinfection.  5.Fungi on dung (coprophilous fungi) The dung is placed on moist filter paper in Petri dishes. When the material cannot be studied immediately, the specimen must be kept dry; in this condition most coprophilous fungi stay alive for a long time without further development.  Pilobolus sp Coprophilous (dung-inhabiting)  6:Fungicolous Fungi Fungicolous fungi comprise a broad range of association between two fungi found living together. one fungus growing on another as a parasite, commensal, or saprobe. The parasitism may be "necrotrophic" (destructive) or "biotrophic" (forming balanced relationships)  7:Entomogenous Fungi Many fungi parasitizing arthropods can be cultivated on artificial media. Mycelium, conidia or hyphal bodies are transferred to agar media (2% malt extract, PDA or Sabouraud agar) with antibiotics  8: Thermophilic and Thermotolerant fungi Thermophilic fungi have a growth optimum between 40 and 50°C and do not grow at or below 20°C. Thermotolerant fungi have a maximum at or below 50 °C and grow well at and below 20 C. Thermophilic fungi are common in compost, manure, hay and other self-heating substrata, and also in superficial soil layers,  isolation of thermophilic and thermotolerant soil fungi: the dilution plate technique or Warcup's soil plates are used with malt agar and antibacterial antibiotics; for thermophilic fungi, plates are incubated at 45 or 50 C, for thermotolerant fungi at 35 or 40 C.  9: Oligotrophic fungi Oligotrophs are microorganisms that can grow in environments where concentrations of nutrients are low or even absent. These occur e.g. in clean (drinking) water, on inert surfaces such as glass or rock. Frequently they actually occur in microniches within more permissive environments, and assimilate compounds that the more rapidly growing saprobes are unable to use  For example, dermatophytes are unique in assimilating keratin, while black yeasts are able to degrade monoaromatic xenobiotics. They are isolated by enrichment by selective isolation techniques. Selective isolation experiments have to be carried out over weeks or months, as oligotrophic fungi grow very slowly, with very small biomass.  Fungi are classified as following: kingdom: protozoa kingdom: Eumycota (Slime moulds) (True Moulds) kingdom: chromista The vegetative phase is Produce non- motile plasmodium (ameoboid Produce motile spores(aplanospores) structure) Slimy, naked (no spores(zoospores) Vegetative body is cell wall), multinucleate Vegetative body is mycelium mass of protoplasm, move mycelium Classified according to by pseudopodia. the method of sexual reproduction Reproductive part: spores  Kingdom: protozoa Phylum Myxostelida e.g. Stemonitis Phylum Dictyostelida Phylum Labyrinthulida Phylum Plasmodiophorida e.g. Plasmodiophora  e.g. Stemonitis fusca Members of Myxomycota are commonly referred to as (slime molds). General Characters : 1. Occurrence: They are found on moist soil, decaying wood , decaying plants leaves, plant debris and animal dung. 2. Not true fungi (lack a cell wall and mycelium). 3. They posses characters of both fungi and animals. *Like fungi (reproduce by spores with a definite cell wall). *Like animals (vegetative structure plasmodium : slimy , naked , multinucleat mass of protoplasm).  The life cycle : 1. Once a spore is released from the fruiting body it's dispersed, either by insects, animals, and rain or air movement. On landing on a suitable location with appropriate moisture and temperature, one to four protoplasts are germinated. 2. The protoplasts once released from the spore's wall through either a pore or fissure will be either a flagellated swarm cell if conditions are wet, or a non- flagellated myxamoebae cell in dryer conditions. 3. If conditions for growth are not suitable, the cells can become microcysts to survive long periods of time. 4. - A diploid zygote is formed when two compatible myxamoebae or swarm cells fuse. This is known as plasmogamy and karyogamy. 5. After a time of feeding and growing, the zygote develops into a single celled multinucleate structure known as a plasmodium. 6. When the conditions are right, the mature plasmodium produces one to many fruiting bodies containing spores depending on species. Phylum 2: plasmodiophorida e.g. Plasmodiophora brassicae Cause (club root of cabbage/ crucifer) : it causes the roots to produce abnormal swellings and malformations through. 1.Hypertrophy : enlargement of cell size. 2.Hyperplasia : uncontrolled cell divisions (increase in cell divisions). 3.The infect cells are filled with the resting spores of the fungus. The life cycle :  Important terms Anamorph: asexual state of fungus Teleomorph: sexual state of fungus Homothallic: two cells or spores or organs responsible for sexual reproduction are similar (physiology, structure or mating type) Heterothallic: two cells or spores or organs responsible for sexual reproduction are distinct or different (physiology, structure or mating type).  Kingdom : Chromista Phylum : Oomycota General characteristics:  Occurrence: Many live in water or soil amd some are important plant pathogens.  Vegetative form: have diploid coenocytic hyphae (most other fungi have haploid hyphae).  cell walls made of cellulose, (other fungi have chitin).  Asexual reproduction: by flagellated zoospores.  Sexual reproduction :Oogamous reproduction between antheridia and oogonia to produce zygot which develops into thick walled Oospore.  Oogamous sexual reproduction antheridium oogonium Oogonium antheridium Homothallic Heterothallic  Phylum : Oomycota Class: Oomycetes Order Peronosporales Pythiales Families Families Peronosporaceae Albuginaceae Pythiogetonaceae Pythiaceae  Family Peronosporaceae Occurrence: Obligate biotrophs of vascular plants causing downy mildews disease vegetative part: “Coenocytic mycelium Asexual reproduction by motile zoospores inside sporangia Sexual by homothallic oogamous Examples: Peronospora, Bremai and Plasmopara  Family Albuginaceae Occurrence: Obligate biotrophs of vascular plants causing white rust disease vegetative part: “Coenocytic mycelium Asexual reproduction by motile zoospores inside sporangia, Sporangia formed in basipetal succession, dispersed by wind Sexual by heterothallic oogamous Examples: Albugo portulacae Kingdom : Eumycota  General characteristics Occurrence: Terrestrial live as saprophytic on dead organic matter and some are coprophilous (occur on dung) and some are parasitic Vegetative part: Cell walls made of chitin(uninucleate, dikaryotic, or coenocytic). Asexual reproduction (anamorph): non- motile spores Sexual reproduction (teleomorph): by specialized spores  Phylum1: Zygomycota 1. Hyphae are coenocytic 2. Flagellated spores are absent 3. Most reproduce asexually by producing sporangiospores within a special sac called the sporangium (the anamorphic phase). 4. Sexual spores are called zygospores contained within a zygosporangium (the teleomorphic phase) formed following gametangial fusion / copulation.  Sexual Reproduction Gametangial congucation May be Homothallic or Heterothallic Heterothallism: two gametes arise from two mycelium genetically different and so requiring a partner for sexual reproduction Homothallism : two gametes arise from two mycelium genetically similar and so able to reproduce sexually without a partner Zygosporangium gametangium  Sexual Reproduction + - Mycelium Progametangia Suspensors karyogamy Zygosporangium Gametangia Zygote Zygospore  Class: zygomycete. order Family mucorales Family Mortierellaceae Mucoraceae Family Family Chaenophoraceae Thamnidiaceae Family Family Cephalidaceae Pilobolaceae  General characters: Well developed, typically coenocytic mycelium Wall composition of chitin Asexual reproduction by formation of sporangiospores cleaved out from the cytoplasm of sporangia (ananmorphic phase) Chlamydospores (thick walled rounded spores) may be formed. Called mucoralean or mucoraceous fungi. Grow and invade quickly on easily digestible substrates, such as those containing starches, sugars, and hemicelluloses. Can act as parasites and/or cause diseases in plants, animals and some insects and humans. Sexual reproduction (teleomorphic phase) spores by gametangial fusion / copulation.  Classification of Mucorales Based on morphology of sporangia : 1: Collumelate sporangia: Sporangia with columella (Family: Mucoraceae) 2: Sporangioles with one or few number of spores. (Family: Cuuninghamellaceae) 3. Merosporangium (sac containing 10 -15 sporangiospores) that occur in a linear sequence. Merosporangia borne on swollen tips of sporangiophores. (Family: Piptocephalidaceae) 4. Single sporangium Sporangial wall densely cutinized above, entire sporangium violently discharged or detached as a whole from sporangiophore. (Family: Pilobolaceae)  Family1: Mucoraceaea Example 1:Rhizopus sp. Saprophytic on dead organic matter, Vegetative thallus is a branching, coenocytic mycelium (N), rhizoids: root-like hyphae that adhere reproductive structures to substrate and stolon to connect two groups of rhizoids. Asexual reproduction takes place by the formation of sporangiophores with terminal columellate sporangia Sexual Reproduction by gametangial conjugation.  Zygomycota - Rhizopus– common molds The fungal mass of hyphae, known as the MYCELIUM penetrates the bread and produces the fruiting bodies on top of the stalks Mycelia = a mass of hyphae or Stolon filaments Rhizoids = root-like hyphae The zhizoids meet underground and mating occurs between hyphae of different molds (SEXUAL REPRODUCTION) Life cycle of Rhizopus sp. (Alternation of generation)  Example 2:Mucor sp. The common pin mold of bread, leather. Family2: Cunninghamellaceaea Eample: Cunninghamella sp. Family3: Piptocephaliodaceaea Eample: Syncephalastrum sp.  Family4: Pilobolaceaea Eample: Pilobolus sp. Coprophilous (dung- inhabiting) spore dispersal mechanism  Spore dispersal mechanism: 1:Beneath the black apical mitosporangium is a lens- like subsporangial vesicle, with a light-sensitive `retina' at its base that controls the growth of the sporangiophore very precisely, aiming it accurately toward any light source. In a word, it is phototropic. 2: Osmotically active compounds (carotene) cause pressure in the sporangiophore and the subsporangial vesicle to build up until it is more than 100 pounds per square inch (7 kilograms per square centimetre). This eventually causes the vesicle to explode, hurling the black sporangium away to a distance of up to 2 metres, directly toward the light. 3: The mucilaginous contents of the subsporangial vesicle go with the sporangium, and glue it to whatever it lands on.