Mycology
- 2. Mycology Presented by Mr. VYAVAHARE YUVARAJ VITTHAL Submitted to Dr. K. S. RAGHUWANSHI POST GRADUATE INSTITUTE, DEPARTMENT OF PLANT PATHOLOGY AND AGRICULTURAL MICROBIOLOGY, MAHATMA PHULE KRISHI VIDYAPEETH, RAHURI
- 3. Content ✓ Introduction ✓ History ✓ Important Characteristic ✓ Reproduction in fungi ✓ Spore and Spore fruiting bodies in fungi ✓ Taxonomic Development of Fungi ✓ Classification of Fungi by Ainsworth And Bisby ✓ Specialized characteristic of Different Fungi ✓ Hetrokaryosis ✓ Parasexual Cycle ✓ Speciation in fungi ✓ Self-incompatibility in Fungi
- 4. Year Scientist Description 1500 Surapal Wrote “Vruksha Ayurveda” the first book in which plant disease were discussed 1665 Robert Hooke Teliospore of Phragmidium disciflorum were first observed under microscope 1670 Thoullier Observed that ergotism (Holy fire) is associated with the consumption of ergot contaminated grains 1729 Pier Antonio Micheli (Italy) Father of Mycology Studied fungi and saw their spores on the pieces of watermelon Wrote “Nova plantarum genera”
- 5. 1755 M. Tillet Great Grand Father of Plant Pathology Demonstrated experimentally that the bunt of wheat was contagious and though that the spores contained a poisonous entity Work published on Stinking smut of wheat 1773 J. Baptista Gave the systemic classification of plant diseases. 1801 CH Persoon Wrote “Synopsis methodical fungorum” a chief starting point for the nomenclature of the Uredinales, Ustilaginales and Gasteromycetes 1807 Prevost Experimentally provided the fist proof and interpretation of the role of microorganism in the causation of the disease Demonstrated the control of wheat smut by steeping seed in CuSO4 solution. 1821 EM Fries Linnaeus of Mycology Father of systemic mycology Regarded the rust and smut fungi as products of diseased plants Wrote "Systema mycologicum
- 6. 1831¬1866 Anton De Bary Father of Plant Pathology Founder of modern Mycology Describes the account of development and sex in number of Phycomycetes and Ascomycetes First to indicate the nature of obligate and facultative forms Describe the role of enzymes in tissue disintegration Working on soft rot of carrot caused by Sclerotinia spp. Wrote text book on "Morphologie und Physiologie der Pilze Demonstrated heteroecious nature of stem rust of wheat Work on late blight of potato 1840 LR Tulsane Reconstructor of Mycology Made drawing of rust smuts and ascomycetes 1854 Schroeder and Von Dusch First time use cotton plugs in culturing of microorganism 1858 Julius Kuhn Published first textbook on Plant pathology namely "The diseases of cultivated crops: Their causes and their control” 1859 C Darwin Wrote "Origin of species”
- 7. 1875 Oscar Brefeld Developed the pure culture technique for isolation and culturing of fungi Studied life history of cereal smuts Discovered Dictyostelium mucoroides 1876 Furlow First introduced independent course of Plant pathology at Haward University 1880 HM Ward Father of Tropical Plant pathology Role of environment in the epidemiology of coffee rust 1880 Hesse Introduced the use of agar in microbiological methods 1885 PMA Millardet Discovered the Bordeaux for the control of downy mildew of grapes
- 8. 1885 Frank Discovered mycorrhizial fungi 1887 Jeensen Hot water treatment for wheat smut 1891 NA Cobb First scale to measure plant disease intensity 1894 Erickson Physiological specialization in stem rust of wheat 1914 EC Stackman Biological forms in cereal rust 1930- Physiological forms of Puccinia graminis tritici by hybridization
- 9. 1923 Hansen and Smith Demonstrated the origin of physiological races through heterokaryosis. 1926 E Kurosawa Describe the role of growth regulators in plant disease by showing that culture fluids of Fusarium moniliforme reproduce symptoms of the Bakane disease of rice. 1927 JH Craigie Discovered function of pycnia 1929 JC Walker Identified protocatechoic acid and catechol as preformed disease resistance factor in red onion bulb against smudge disease
- 10. 1931 PA Saccardo Wrote “Syllogue Fungorum” comprised of 26 volume Providing latin description of all genera and species known at that time 1940 KO Mullar and H Borger Proposed Phytoalexin hypothesis Studied hypersensitive response in potato Phytophthora system 1946 HH Flor Gave Gene for gene hypothesis of disease resistance and susceptibility while working on linseed rust (Melampsora lini)
- 11. 1947 F Mecham and M Murphy Discovered toxin Victorin 1952 G Pantecorvo and JA Roper Discovered parasexuality in Aspergillus nidulans 1953 EC Large Term pathometry or phytopathometry for disease I assessment and disease measurment 1966 Williams Axenic culture of rust fungus (Puccinia graminis f.sp. tritici) from uredeniospore 1968 Vander Plank Father of plant epidemiology Gave concept of horizontal and vertical resistance in plants Vertifolia effect 1984 Albersheim Identified molecule in cell wall of the oomycetes Phytophthora megasperma that acts as the elicitor of the defence response in the soybean host
- 12. 1986 R Beachy Demonstrated that transgenic tobacco plants expressing the coat protein gene of TMV exhibit resistant to the virus 1990 DF Klessig and I Raskin Demonstrated that salicylic acid is associated with SAR 1991 PJGM DeWit Cloned the first fungal avirulence gene avr9 from Cladosporium fulvum 1992 SP Briggs and JD Walton Cloned the first resistant gene Hm-1 from corm Demonstrated that its protein product detoxified the host selective toxin of Cochliobolus carbonum
- 13. 1993 GB Martin Cloned the first disease resistance gene Pto modulating the HR 1998 Gilchrist Reported connection between plant disease and PCD suicide or apoptosis associated with HR 2003 JE Galagan The first complete genome sequencing of a fungus Neurospora crassa 2005 RA Dean The first complete genome sequencing of a plant pathogenic fungus Magnaporthe grisea
- 14. General Characteristics of Fungi 1. Vegetative Thallus: The body of the fungus is called as Thallus, which is without stem root and leaves. Some fungi may be unicellular yeasts while some fungi may be multi cellular moulds. A single thread like filament is called as hypha. A hypha is made up of a thin, transparent tabular wall filled or lined with a layer of protoplasm. A group of hypha or network of hyphae constituting the body of fungus is called as mycelium may be septate or aseptate. i.e coenocytic or Nonseptate. a) Nonseptate or Aseptate or Coenocetic Mycelium: b) b) Septate Mycelium or Non-coenocetic Mycelium
- 15. i) Ecotophytic Mycelium: ii) Endophytic Mycelium: a)Intercellular b) Intracellular c) Vascular
- 16. 2. Cell Wall: Cell wall is well defined, typically chitinised which contains chitin or cellulose or both (Cellulose in oomycetes), living structure of the cell called as organells (Cytoplasm, nucleolus and protoplasm). Nonliving structure of the cell called as Inorganells (Chitin , cellulose). 3. Nutrition: their food as: 1.Saprobes ( example- Mushroom) 2. Symbionts (example- Lichen.) 3. Parasites or hyper parasites (example- Stem rust of Wheat.)
- 17. i) Obligate Parasites or Biotrophs: 3. Parasites: E.g. Rust, mildews, viruses. (Stem Rust of Wheat) ii) Non Obligate Parasites or Necrotrophs: E.g. Sclerotium rolfsii, Claviceps, Ventruria. (Cercospora Leaf Spot og Groundnut) iii) Facultative Saprophytes: . E. g. Smut, Sphacelotheca sp. (Head Smut of Jowar) iv) Facultative Parasites: E.g. Pythium, Phytophthora. (Late Blight of Potato)
- 18. 4. Nuclear Status: Eukaryotic multinucleate, mycelium being homocakaryotic or heterokaryotic or haploid or diploid or dikarytoic limited duration. Well defined structures i.e. nuclear membrane, nucleolus, and chromatin material. 5. Sexuality: Sexual or asexual and homo or heterothallic. 6. Life Cycle: Simple to Complex. 7. Sporocarps: Microscopic or macroscopic and showing limited differentiation. 8. Distribution: Cosmopolitan.
- 20. Reproduction in Fungi Reproduction: Asexual Reproduction: It is also known as somatic or vegetative reproduction and does not involve the union of two nucleus or sex organs. Methods of Asexual Reproduction: A. Binary fission B. Budding C. By fragmentation of soma or cell sap or hyphae (Arthospore) D. Production of spores (Chlymadospore) Sexual Reproduction: Union of two nuclei or gametes of opposite sex a gamete is unisexual. i.e. haploid. Methods of Sexual Reproduction: a. Planogamtic Copulation b. Gametangial Contact c. Gametangial Copulation d. Spermatization e. Somatogamy f. Heterokaryasis g. Dikaryotization.
- 21. Asexual Reproduction in Fungi A) Binary Fission B) Budding C) Fragmentation D) Spore Formation (chlamydospore)
- 22. Sexual Reproduction In Fungi A) Planogametic copulation B) Gametangial contact C) Gametangial copulation D) Spematization E) Somatogamy A C B D and E
- 23. Different Types of Spore in Fungi
- 24. Sexual Fruiting bodies in Fungi
- 25. Asexual Fruiting Bodies in Fungi A) Sporangium B) Aecium C) Pycnidium D) Acervulus E) Sporodochium F) Coremium (Synnemata) G) Pycnium A B C D E F G
- 27. Specia
- 28. Specialized Asexual Spore Structure
- 29. Major criteria used in the classification and phylogeny of fungi 1. Morphology 2. Anatomical Characters 3. Nutrition and Physiology 4. Chemistry of Low-Molecular-Weight Compounds 5. Carbohydrates and Cell Wall Composition 6. Molecular Methods
- 30. • Basic shape of the fungal thallus. • Form, colour and size of the asexual or sexual spore producing structures. 1.Morphology
- 31. 2. Anatomical Characters • The arrangement of hyphae comprising the tissues of spore- producing structures • The arrangement of asci or basidia and also the sterile structures like paraphysis and cystidia within the hymenium. • Analysis of hyphal structures. • Histochemical localization of certain compounds by using fluorescent probes and dyes.
- 32. They are of great practical importance in yeasts because of their limited morphological features and absence of sexual sporulation in some. Features of importance are: • Whether growth is limited to aerobic/anaerobic conditions or fermentation occurs. • Whether it can utilize nitrate as a nitrogen source. • Which sugars and glycosides it can metabolize? • What is the pattern of susceptibility to various antifungal compounds? 3. Nutrition and Physiology
- 33. The term chemotaxonomy is generally applied to the utilization of low molecular weight compounds in classification and identification This approach is important to understand lichen taxonomy as they are known to produce a wide variety of secondary metabolites, such as pigments, colorless compounds, and some products in the form of crystals This approach relies on procedures such as Gas Chromatography (GC), Mass Spectrometry (GCMS), High Performance Liquid Chromatography (HPLC) and Nuclear Magnetic Resonance (NMR). 4.Chemistry of Low-Molecular-Weight Compounds
- 34. • Fungal walls have a complex structure with specific polysaccharides present in different groups for example the walls of Oomycota contain cellulose, whereas in most other fungi chitin is present. • Estimates of the amount chitin have been significantly employed in yeast taxonomy. • Glucose and mannose are the main carbohydrates found on hydrolysis of the walls of all yeasts. However, presence or absence of certain sugars like fucose, galactose, rhamnose and xylose, though in smaller amounts, may also help in classifying yeasts. 5.Carbohydrates and Cell Wall Composition
- 35. • These methods are based either directly on the DNA sequence characters or on the properties of their protein products, especially enzymes. • This can provide information on the direction of evolution leading to the development of a phylogenetic tree. 6. Molecular Methods
- 36. Some earlier systems of classification 1. System proposed by HCI Gwynne-Vaughan & B Barnes (1937).
- 37. 2. System proposed by EA Bessey (1950).
- 38. 3. System proposed by GM Smith (1955) GM Smith an American botanist (1885-1959), proposed to include all fungi into seven classes belonging to two divisions.
- 39. Fungi Lower Fungi (Phycomycetes) Higher Fungi • Group 1 Uniflagellatae • Class 1 Chytridiomycetes • Class 2 Hyphochytridiomycetes • Class 3 Plasmodiophoromycetes • Group 2 Biflagellatae • Class 1 Oomycetes • Group 3 Aplanatae • Class 1 Zygomycetes • Class 2 Trichomycetes • Class 1 Ascomycetes • Subclass 1 Hemiascomycetidae • Subclass 2 Euascomycetidae • Subclass 3 Loculoascomycetidae • Subclass4Laboulbeniomycetidae • Class 2 Basidiomycetes • Subclass 1 Heterobasidiomycetidae • Subclass 2 Homobasidiomycetidae 4. Outline of the classification proposed by Lilian E Hawker (1966).
- 40. 5. System proposed by Greta B Stevenson (1970 • Division Mycota • Class 1 Chytridiomycetes • Class 2 Oomycetes • Class 3 Zygomycetes • Class 4 Ascomycetes • Class 5 Basidiomycetes • Class 6 Deuteromycetes
- 41. 7.Classification of organism by R.H.Whittakar (1969) • R.H. Whittaker (1969) • Classification of organism in Five Kingdom System 1) Kingdom Protista 2) Kingdom Monera 3) Kingdom Fungi 4) Kingdom Animalia 5) Kingdom Plantae
- 42. Taxonomic Position of fungi Ends Kingdom- Division mycota Sub-Division mycotina Class mycetes Order ales Family ceae Genera Species Classification of Fungi by G.C. Ainsworth (1973)
- 43. Schematic representation of the outline with figure, the classification of G.C. Ainsworth (1973) is given: Schematic outline of the classification of G. C. Ainsworth (1973):
- 44. Y6767-7l=ui’;/+
- 46. Classification of Fungi by Hawksworth et al. (1983 and 1995): Ten years after the classification of Ainsworth (1973), Hawksworth et al. (1983) revised Ainsworth’s classification in the 7th edition of the “Dictionary of the Fungi”. The changes made by them are: 1. The Division Myxomycota divided into eight classes instead of four classes. 2. The Sub-division Ascomycotina is directly divided into thirty seven (37) orders and arranged alphabetically; there is no classes in- between. 3. The subdivision Basidiomycotina is divided into four classes instead of three, where class Teliomycetes is replaced by Uredinio- mycetes and Ustilaginomycetes. 4. In the sub-division Deuteromycotina, the class Blastomycetes was not considered.
- 47. Later, Hawksworth et al. (1995) thoroughly revised the classification in the 8th edition of the “Dictionary of the Fungi”. The classification was based on the sequence of 18s rRNA among the different members. • Though members of fungi show similarity in their morphology, mode of nutrition and ecology, but the higher dissimilarity is observed in the base sequences of their 18s rRNA (or more precisely in the DNA coding for it), which is now considered as the most important parameter to determine the genetic relationship. Thus, it shows that the fungi are polyphyletic aggregation of unrelated members. • Based on the above fact and phylogenetic consideration, the entire fungal community are now segregated out and placed them under three different Kingdoms Fungi, Straminopila (Chromista) and Protozoa. • Based on comparison of several factors such as, 18s rRNA, cytoskele- ton protein, chemical features like chitin, mitochondrial codon UGA coding for tryptophan instead of termination, storage of glycogen, elongation factors and morphological structure of motile cells like male gamete in animal and zoospores in fungi, there is close similarity of fungi with animals than to other two groups like Straminopila and Protozoa.
- 48. Modern systems of classification Fungal taxonomy is evolving at an unprecedented speed at present due mainly to the contributions of molecular phylogeny. These classification systems are based on evolutionary relationships and are known as phylogenetic classifications.
- 49. Outline of classification system proposed by CJ Alexopoulos, CW Mims and M Blackwell (1996)
- 50. Outline of classification system adopted by J Webster, and Roland WS Weber in their book, Introduction to Fungi (2007) This classification scheme is based on the classification proposed by McLaughlin et al (2001). Mainly this scheme also is based on molecular phylogeny and is broadly same as proposed by Alexopoulos et al. (1996). The phylogenetic relationships of Fungi and fungus-like organisms studied by mycologists with other groups of Eukaryota.The analysis is based on comparisons of18S rDNA sequences.
- 51. The different taxa considered in this system are
- 53. • The different taxa considered in this system along with their ‘ending’ are: • Phylum — mycota • Sub-phylum — mycotina • Class — mycetes • Sub-class — mycetidae • Order — ales • Family — aceae • But the genera and species have no standard ending. In this system, division has been replaced by phylum and all taxa are written in italics.
- 54. Clamp connections • Branch that grows back
- 55. Clamp connections • Thought to be a mechanism to maintain dikaryotic condition • Only found in dikaryotic hyphae, but not all dikaryotic hyphae form them
- 56. • The clamp connection: Found in all dikaryotic mycelia of basidiomycota except for most uredinomycetes
- 60. Heterokaryosis ✓ Heterokaryosis - coexistence of genetically different nuclei in cytoplasm continuity with one another. ✓ Discovered by Hansen and Smith (1932) in Botrytis cinerea. ✓ plays major role - variability and sexuality in fungi. Heterokaryotic condition arises by- ➢ Mutation ➢ Anastomosis ➢ Inclusion of dissimilar nuclei in spores after meiosis, in heterothallic fungi. In Ascomycotina and Basidiomycotina
- 61. ▪ Mutation- A high frequency of mutation is characteristic of fungi - main source of variability. ❖ Anastomosis (fusion of hyphae)- Fusion is mostly intra-specific. ➢ Nuclear migration from the point of fusion to the remainder of the mycelium takes place - heterokaryotic mycelium. E.g.- development of heterokaryon in basidiomycota. • in Basidiomycetes, the dikaryotic state differs drastically from the haploid mycelium and spores of the fungus. state differs drastically from the haploid mycelium and spores of the fungus.
- 62. ❖ Inclusion of dissimilar nuclei in spores after meiosis, in heterothallic fungi- ➢ Meiosis results in the production of genetically different nuclei sharing common cytoplasm. ➢ e.g. Neurospora tetrasperma, Podospora anserine ➢ on germination - give rise to a heterokaryotic thallus. ➢ In the asexual phase - occurs frequently in multinucleate spores.
- 63. Parasexual Cycle
- 64. SIGNIFICANCE OF HETEROKARYOSIS ➢ Substitute for heterozygosity and variability ➢ Heterokaryosis and pathogenicity- e.g. in rusts and smuts ➢ Origin of new race ➢ Initial step in Parasexual cycle
- 65. Parasexual cycle • Discovered in fungi (Aspergillus nidulans) by Pontecorvo and Roper (1952) • Parasexuality - genetic recombination is achieved through “ mitotic crossing over” and “ haploidization”. • also known as somatic recombination. • Sexual reproduction - extremely uniform - fine coordination between recombination, segregation and reduction • Parasexual cycle lack such co-ordination • The steps of the parasexual - independent of each other and the frequency of each is very low. • The karyogamy and haploidization are accidential events not bound by space and time.
- 66. STEPS OF PARASEXUAL CYCLE ➢ Establishment of heterokaryosis ➢ Formation of heterozygous diploids ➢ Occasional mitotic crossing- over, during multiplication of the diploid nuclei, and ➢ Haploidization through aneuploidy • Establishment of heterokaryosis The presence of haploid nuclei of dissimilar genotypes in the same cytoplasm • pre-requisite for recombination.
- 67. FORMATION OF HETEROZYGOUS DIPLOIDS • Nuclear fusion in heterokaryotic somatic cells was first noted by Roper (1952) in Aspergillus nidulans. • The nuclear fusion between dissimilar nuclei - the formation of heterozygous diploid nuclei or “zygotes” • a rare event, occurring at the rate of one in a million. • The heterozygous diploid nuclei - fairly stable • The diploid colonies are recognized by- ➢ higher DNA content of their nuclei ➢ the bigger size of their conidia ➢ certain phenotypic characteristics of their colony • The prolonged diploid phase involving repeated nuclear divisions, enhances the chances of “mitotic crossing over”.
- 69. USE OF PARASEXUAL PHENOMENON IN ANTIBIOTIC INDUSTRY • most important antibiotic producing fungi, like Penicillium chrysogenum (penicillin) and Acremonium chrysogenum (cephalosporin) • discovery of parasexual phenomenon - suitable techniques to obtain higher antibiotic strains. Fungi Antibiotic Aspergillus nidulans Penicillin G Acremonium chrysogenum Cephalosporin C Emerocellopsis salmosynnemata Penicillin N Penicillium chrysogenum Penicillin G, O, V Penicillium patulum Griseofulvin, patulin
- 70. Speciation in fungi • When fungal species parasitize a number of host varieties, they often develop physiological specialization • Eriksson (1894) showed that Puccinia graminis on cereals and grasses is composed of several pathogenically different strains which he describe as specialized forms. • Physiological specialization: – with in the species of a pathogen there exist certain individuals that are morphologically similar but differs with respect to their physiology, biochemical characters and pathogenicity and are differentiated on the basis of their reaction on certain host genera or cultivars The entire population of a particular organism e.g., a fungal pathogen, has certain morphological and other phenotypic characteristics in common and makes up the species of pathogen, such as Puccinia graminis • Physiological race: – a group of population within a species which have ability of infecting a particular genotype and do not differ in their morphology but have physiological differences such as a specific host or food type or pathogenicity E.g. Black stem rust- Puccinia graminis tritici Some individuals of this species make up groups that are called varieties or special forms such as P. graminis tritici and P. graminis hordei.
- 71. • Variability: it is the property of an organism to change its characters from one generation to the other Occasionally, one of the offspring of a race can suddenly attack a new variety or can cause severe symptoms on a variety. This individual is called a variant. Forma specialis (f. sp.) individuals within the species of pathogen that morphologically similar but differ with respect to their pathogenicity on particular host genera or cultivar • With in species or f. sp. There are further subgroups of individual that infect different varieties of the host– such subgroups are called RACES/ STRAINS Even within each special form, however, some individuals attack some of the varieties of the host plant but not others, with each group of such individuals making up a race. Thus, there are more than 200 races of P. graminis tritici (race 1, race 15, race 59 and so on).