Basidiomycotina
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The document discusses the phylum Basidiomycotina and provides details about three major classes: Uredinomycetes, Ustomycetes, and Basidiomycetes. It focuses on characteristics of rust fungi (order Uredinales) and smut fungi (order Ustilaginales), including that rusts require two hosts to complete their lifecycle and are obligate parasites, while smuts are facultative saprophytes. Specific examples of the rust fungus Puccinia graminis and the smut genus Ustilago are also outlined.
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Basidiomycotina
- 1. Basidiomycotina Mushrooms, bracket fungi, puffballs, rusts and smuts
- 2. Basidiomycota • Large phylum – 16,000 spp of higher fungi • All produce a basidium – club shaped structure (site of karyogamy & meiosis) that produces haploid basidiospores
- 3. Basidiomycota • Three classes • Basidiomycetes – produce a basidia, (multicellular fruiting body), includes the mushrooms, brackets, puffballs, jelly fungi, stinkhorns • Uredinomycetes – no basidia, teliospore produces basidia, obligate plant parasites, the rusts • Ustomycetes – no basidia, teliospore produces basidia, facultative plant parasites, the smuts
- 4. Basidia • Basidia divided into two types depending on whether they are septate • Septate basidia – phragmobasidia – Septa can be transverse or longitudinal • Aseptate basidia - holobasidia
- 6. OTHER EXAMPLES OF HOLOBASIDIA AND PHRAGMOBASIDIA
- 7. Hyphae • Hyphae are regularly septate • Specialized type of pore can occur – dolipore septum with parenthosome • Allows cytoplasmic movement but prevents nuclear migration from one compartment to the next
- 8. Basidiomycetes 5. Three types of hyphae a. Primary hyphae – develops from a germinating basidiospore. Nuclear status = n b. Secondary hypha – results from fusion of two primary hyphae. Yields a n+n cell that continues to grow as a n+n hyphae c. Tertiary hypha – exactly the same as secondary hypha. n+n However it has thick walls that enable production of fleshy and wood sporophores Primary hyphae Primary hyphae Secondary hyphae Tertiary hyphae
- 9. • Most Basidiomycetes are heterothallic • Haploid basidiospores germinate to produce haploid mycelium = primary mycelium • In some species, the primary mycelium contains one nucleus in each compartment called monokaryon Dikaryon
- 10. Dikaryon • Plasmogamy occurs shortly after basidiospore germination • Plasmogamy occurs between two compatible hyphae • Plasmogamy initiates dikaryotic phase or the secondary mycelium (dikaryon) • After plasmogamy, nuclei migrate into monokaryotic cells to establish dikaryotic condition
- 11. Basidiospore germinate Primary hyphae Secondary hyphae Dikariotic hypae Basidiospore germinate Dikaryon
- 12. • As mycelium grows, nuclei divide conjugately to maintain dikaryotic condition in cells • Dolipore septum prevents nuclear migration so that each compartment contains two nuclei, pore is 0.1-0.2 μm in diameter • Under certain conditions (e.g. after plasmogamy), dolipore septum breaks down to allow nuclear migration Clamp connections
- 13. • Secondary mycelium is the major vegetative phase of Basidiomycota • Many Basidiomycetes also form clamp connections (formation is reminiscent of crozier formation in Ascomycota) Clamp connections
- 14. Clamp connections • Branch that grows back
- 15. Clamp connections • Thought to be a mechanism to maintain dikaryotic condition • Only found in dikaryotic hyphae, but not all dikaryotic hyphae form them
- 16. • Development of basidium and basibiospores
- 17. Dikaryon • Favorable environmental conditions stimulate formation of basidium karyogamy meiosis
- 19. Discharge of basidiospore • Basidia with sterigmata can actively discharge basidiospores • Basidiospores are positioned at a 45 angle • 5-10 seconds before discharge a droplet forms of water bubble
- 21. Basidium • Basidia are produced in hymenia – fertile regions in the basidioma (will discuss position in different basidiomata)
- 22. Basidia • Spore is discharged less than a mm, then drops straight down • Hymenia must be vertical with respect of gravity
- 23. Basidium • Basidiospores fall out of basidium, into turbulent air current and are carried away
- 24. Basidium • Sterigma (pl. –mata) – projections from basidium to basidiospores • Basidia may or may not produce sterigmata
- 25. Basidium • Composed entirely of dikaryotic hyphae • Basidioma is generally divided into 3 zones – Hymenium – layer of basidia with basidiospores – Subhymenium – distinct area that gives rise to hymenium – Trama – comprises the bulk of the basidium, separates hymenia
- 26. Class - Basidiomycetes • Produce macroscopic basidia • Most produce holobasidia, phragmobasidia produced by some jelly fungi • Large and diverse class • In life cycle, dikaryotic mycelium becomes the major vegetative mycelium
- 27. Agaricales • Large order - ~5000 spp • Hymenium lines surfaces of tubes or gills in fleshy basidiomata • Includes the mushrooms and boletes • Primarily saprotrophs in soil, litter or wood • Many are biotrophic – form mycorrhizal associations with trees • Economically important as cultivated mushrooms and mycorrhizae (used in forestry)
- 28. Systematic position: Kingdom: Mycetae Division: Eumycota Subdivision: Basidiomycotina Class: Hymenomycetes Sub-class: Holobasidiomycetedae Order: Agaricales Family: Agaricaceae Genus: Agaricus Species : A. bisporus, A campestris Genus: Agaricus
- 29. Fig: Perennial nature of Agaricus:
- 30. Agaricales • Basidiomata arise from extensive perennial mycelia • Overall structure of basidia
- 31. Fig: Agaricus campestris anatomy of the pileus
- 32. Gills • Increased surface area for greater number of basidia
- 33. Basidioma development • Hemiangiocarpic development – button is surrounded by a layer of tissue, the universal veil (forms the volva and scales) , also contains a partial veil (forms the annulus and cortina)
- 34. Basidioma development • Pseudoangiocarpic development – button has only a partial veil (forms annulus and cortina)
- 36. Phylum Basidiomycotina: Three major classes • Class Uredinoiomycetes – Order Uredinales - The Rusts • Class Ustomycetes – Order Ustilaginales - The Smuts – • Class Basidiomycetes – Order Agaricales – the gilled mushrooms - caps, oyster mushrooms, etc.
- 37. Uredinomycetes Order Uredinales – the rusts i. Produce all five spore stages – aeciospores, uredospores, teliospores, basidiospores and spermatia (aka pycniospores) ii. Important genera – Puccinia, Gymnosporangium Ustomycetes Order Ustilaginales – the smuts i. Produce only basidiospores and teliospores ii. Important genera – Ustilago, Tilletia
- 38. RUST AND SMUT FUNGI – Uredinales (rusts) – Ustilaginales (smuts)
- 39. Order Uredinales Order Ustilaginales
- 40. The Rusts These are obligate parasites. Generally these require two host to complete their lifecycle. Primary hosts – the host on which basidia and basidiospores are produced. Alternate host – the other host in the life cycle on which spermagonia and aecia are produced Alternative host – the host that a pathogen can infect in place of the primary or alternate hosts. Heteroecious – organisms with a primary and alternate host. Autoecious – organisms that have only a single (primary) host. Macrocyclic rust – long cycle rust. Produce all 5 spore types. Demicyclic rust – medium cycle rust. Omits uredia. Microcyclic rust – short cycle rusts. Produces basidiospores, teliospores and spermatia.
- 41. • The genus includes about 3000 species of these 147 has been reported from India. • It causes a rust disease - black stem rust of Wheat. •Puccinia graminis is an obligate parasite. •It is a heteroecious parasite. •It completes its life cycle on wheat and on barberry. •Wheat is a primary host. •Barberry is a secondary or alternate host. Puccinia
- 42. The Rusts • Stem Rust of Wheat caused by Puccinia graminis –Reduces yield and quality of grain; fungus causes lesions or pustules on wheat stems. –Management - remove alternate host (i.e., barberry); use resistant cultivars of wheat
- 43. Systematic position: Kingdom: Mycetae Division: Eumycota Subdivision: Basidiomycotina Class: Teliomycetes/ Uredinoiomycetes Order: Uredinales Family: Pucciniaceae Genus: Puccinia Species : P. graminis-tritici, P. graminis-hordei, P. graminis- avenae, P. graminis-secale. Genus: PUCCINIA
- 44. •Puccinia graminis forma specialis tritici •The fungus causing black stem rust of wheat •Macrocyclic, heteroecious rusts (those producing all five spore forms and moving between two different hosts)
- 45. Spore-producing stages: 0 =Pycnial/Spermogonial stage: spermatia/pycniospore (n) I =Aecial/Aecidial stage: aeciospore/aecidiospore (n+n) II =Uredial/Uredinial stage: uredospore/urediniospore (n+n) III =Telial stage: teliospore/telutospore (n+n>2n) IV=Basidial stage: basidispore (n) Stages 0 and I on barberry bushes (Berberis vulgaris: dicot) Stages II and III on various grasses (monocot) Stage IV on soil Contd…
- 46. Puccnia Infected Plant Parts
- 47. • Acediospores from berberry bushes fall on wheat stem or leaf, germinates to form dikaryotic, filamentous, well developed, branched, intercellular mycelium • The hyphae of the dikaryotic mycelium - aggregate near the surface of the infected organ to form a hyphal mass known as Uredia. • The tips of hyphae swell to form binucleate oval uredospore in a group known as uredinium or uredosorus. Uredial Stage Stage II
- 48. Uredosori on different parts of wheat
- 49. • They exert pressure on the epidermis, cause rupture and rusty coloured uredospores are seen • Each uredospore contains a pair of nuclei (n + n) cominig from dikaryotic hypha. • To obtain nutrition haplophase develop haustoria.
- 50. Mycelium
- 51. Puccinia Uredosorus in Wheat
- 52. Uredospore are stalked, unicellular oval, binucleate structures, rusty red in colour.
- 53. Telial Stage: • Late in growing season, uredospores are metamorphosed into telutospores in the same Uredosori. • Uredosori is known as Telutosori. • Telutospores are dark brown or black in colour. Stage III
- 54. Stage III: Telia bearing teliospores (n+n>2n)
- 56. Telutospores dark brown or black in colour. stalked, two celled, spindle shaped. The wall is thick, black and smooth.
- 57. Puccinia teluto spores •Each cell has two nuclei (one plus strain and the other of minus strain). •final stage on primary host •Telutospore matures, the nuclei in each cell fuse to form a diploid nucleus (Kayogamy) (2N).
- 58. Germination of Telutospore • On Soil/ wheat straw • Favourable condition- Proper Temperature, Moisture • Germination of Teluto spore- germination tube - Epibasidium
- 60. Germinated Teluto spore and formation of Basidium & Basidio spores Epibasidium Basidio spore (+) Or (-)Sterigmata Hypobasidium Basidium
- 61. Stages of Puccinia on Barberry leaf • Pycnial stage: On upper epidermis with +ve and – ve basidiospores (Sexual reproduction) (Plasmogamy) • Aecidiospore stage: On lower epidermis, Binucleate Aecidiospore
- 62. Basidiospores which are of + and - mating types, land on a young leaf of barberry in spring, and initiate localized monokaryotic infections. The hyphae are intercellular, but they send haustoria into host cells to absorb food
- 63. Basidiospores (+ and -) Basidiospores germinate on upper epidermis of Barberry leaf and produce Pycniosporangium
- 64. Puccinia Pycnium on Upper epidermis
- 65. Infection of Puccinia on Barberry leaf Lower and Upper sides
- 66. Each Pycniosporangium forms Pycniospore which ooze out in a sweet-smelling nectar. A tuft of receptive hyphae also grows out from the neck of the Pycniosporangium. Insects are attracted by the nectar, and transfer spermatia of each mating type to receptive hyphae of the other type. This process, analogous to pollination, initiates the dikaryophase The dikaryotization spreads to the lower surface of the barberry leaf, where the fungus has already produced the primordia of cup-like aecia (stage I). Aeciospores cannot infect barberry.
- 67. Receptive hyphae and Spermatia Spermatia Receptive hyphae
- 69. Stage I: Aecia bearing aeciospores (n+n)
- 70. •Puccinia- Aecio sporangium on lower epidermis aeciospores infect primary host. Aeciospores produced on alternate host (e.g.,Barberry) infect primary host (e.g., grasses)
- 71. • Aeciospores- round, yellowish red, Unicellular, binucleate, thick walled, 6 germ pores. • Germinate on wheat plant. Aeciospores Aecial cup
- 72. Puccinia- Polymorphic fungi • Polymorphism: Various types of spores produced during life cycle according to hosts life cycle and climatic condition. • Known as Polymorphism. • Fungi shows polymorphism known as Polymorphic fungi.
- 76. Genus-Ustilago Systematic position Sub-Division: Basidiomycotina Class: Teliomycetes Order: Ustilaginale Family: Ustilaginaceae Genus: Ustilago
- 77. • Order- Ustilaginales (smut fungi) • Basibiospores are sessile and produced directly on promycelium. • Basibiospores are passively discharged. • Facultative saprophyte. • Teliospore (one celled) most intercalary.
- 78. • Some species of smut fungi with their hosts: U. tritici ------loose smut of wheat U. hardei ----- cover smut of barley U. nuda ------lose smut of barley U. scitaminea ----smut of sugarcane
- 79. Smut • Obligate parasites (cereals) • Replace kernels with spore masses • 2 spores: teliospores and basidiospores (sporidia)
- 80. Ustilago maydis corn smut (Agrios 583-584) Overwinters as teliospores in debris Basidiospores produced in spring Infect all tissues Must fuse to form dikaryon to grow
- 82. Loose Smut of Barley Ustilago nuda Agrios 584-588
- 83. Loose smut of cereals
- 84. Uredinales (rusts) Ustilaginales (smuts) 1. Teliospores terminal. 1. Teliospores intercalary. 2. Basidiospores 4, discharged from sterigmata. 2. Basidiospores variable in number, not on sterigmata, not discharged. 3. Spermagonia produce dikaryotic stage. 3. No spermagonia; dikaryotic stage. stage arises from fusion of any two compatible cells. 4. Clamp connections absent. 4. Clamp connections common. 5. Many species require two hosts for complete life cycle. 5. Never requires two hosts. 6. Most species unculturable on artificial media. 6. Most species readily culturable. 7. Infections usually localized. 7. Infections usually systemic. 8. Teliospores in telial sori, usually on stems or leaves. 8. Teliospores replace host organs, usually ovaries and anthers. 9. Attack ferns, gymnosperms, or angiosperms. 9. Attack only angiosperms. Comparison of Rust & Smut Fungi