Lecture- 22 - Classification of Basidiomycota.pptx

Microbiology

1. Lecture-22: Classification of Kingdom - Basidiomycota - important characters Dr. P. Renukadevi Professor (Plant Pathology)

2. Domain : Eukarya Kingdom : Fungi Division : Basidiomycota Subdivision Classification of Basidiomycota Agaricomycotina Pucciniomycotina Ustilaginomycotina

3. Classification of Basidiomycota Subdivision: Agaricomycotina Class: Agaricomycetes Subclass: Agaricomycetidae Subclass: Incertae sedis Order: Agaricales Boletales Atheliales Family: Boletaceae Genus: Boletus Family: Atheliaceae Genus: Athelium Order: Cantharellales Order: Polyporales Family: Ceratobasidiaceae Genus: Ceratobasidium Family: Tulsanellaceae Genus: Tulsanella Family: Polyporaceae Genus: Polypores , Fomes Family: Ganodermataceae Genus: Ganoderma Agaricaceae

4. Classification of Basidiomycota Order: Agaricales Family : Agaricaceae Genus: Agaricus , Coprinus , Lycoperdon Family : Amanitaceae Genus: Amanita Family : Trichlomataceae Genus: Armillaria Family : Pleurotaceae Genus: Pleurotus Family : Pluteaceae Genus: Volvariella Family : Lyophyllaceae Genus: Calocybe

5. Classification of Basidiomycota Subdivision: Pucciniomycotina Class: Pucciniomycetes Order: Pucciniales Order: Septobasidiales Order: Helicobasidiales Helicobasidiaceae Helicobasidium Pucciniaceae Puccinia Cronartiacaeae Cronartium Melampsoraceae Melampsora Phragmidiacaeae Phragmidium Phakapsporaceae Phakapspora Raveneliaceae Ravenelia Incertae sedis Hemileia

6. Classification of Basidiomycota Subdivision: Ustilaginomycotina Class: Ustilaginomycetes Class: Exobasidiomycetes Order: Ustilaginales Order: Urocystidiales Anthracoideaceae Tolyposporium Urocystidiaceae Urocystis Ustilaginaceae Ustilago Order: Exobasidiales Order: Entylomatales Order: Georgefischeriales Order: Tilletiales Graphiolaceae Graphiola Exobasidiaceae Exobasidium Entylomataceae Entyloma Tilletiaceae Tilletia Neovassia Eballistraceae Eballistra

7. General Characters of Basidiomycota Commonly called as “Club Fungi” Consists of Filamentous Fungi – Septate hyphae with perforated “ Dolipore septum” which allows cytoplasm to flow freely between cells Cell components are made up of Chitin and Glucan Reproduce by both sexually and asexually It possess mostly single club shaped basidium on which four basidiospores are borne at the tips of minute stalks called sterigmata Actively discharged basidiospores – Ballistospores Passively discharged basidiospores – Statismospores Clamp connection Basidium Basidiospores Sterigma Basidium with Basidiospores

8. Basidium arrangement

9. Primary Hyphae – develops from a germinating basidiospore . Nuclear status = n Secondary Hyphae – results from fusion of two primary hyphae . Yields n+n cell that continues to grow as a n+n hyphae Tertiary hyphae – exactly the same as secondary hyphae , n+n . However, it has thick walls that enable production of fleshy and wood sporophores 3 types of Hypha

10. The word  basidium  literally means "little pedestal“ A  basidium is a microscopic spore-producing structure found on the  hymenophore  of reproductive bodies  of  basidiomycete  fungi These bodies also called tertiary mycelia , which are highly coiled versions of secondary mycelia A basidium usually bears four sexual spores called  basidiospores A partially grown basidium is known as a   basidiole . Basidium Basidium with Basidiospores

11. Holobasidium Holobasidium : a non- septate basidium ; single-celled, typically club-shaped, and bearing sterigmata (usually four ) More or less  clavate , with  sterigmata  that are fairly small in proportion to the  basidium Gilled mushrooms,  boletes , polypore, chanterelles, tooth fungi have this type of  basidium , and are called Holobasidiomycetes Also called a  homobasidium Type of Basidium

12. A phragmobasidium is  a basidium divided into separate cells following meiosis The  basidium is separated by the elongated two or four cells of septa. A basidium that is divided into more than one cell by transverse or longitudinal setpa In cross-section the metabasidium appears as four cells Jelly fungi and the rusts and smuts Phragmobasidium Type of Basidium

13. Different Types of Holo and Phragmobasidium

14. Dolipore Septum Dolipore septa are specialized dividing walls between cells (septa) Have a barrel-shaped swelling around their central pore, which is about 0.1–0.2 µm wide/ typically capped at either end by specialized membranes, called " parenthesomes “ or “pore caps” All dolipore septa can allow cytoplasm, and sometimes mitochondria, to flow through their pores those in monokaryotic hyphae have perforated parenthesomes , which allow cell nuclei to flow through as well The function of the dolipore septum is the repair of the damages in the hyphal . The damage of the hyphae is mainly caused by the plugging of the electron dense material in the septum of the hyphae . This is the rapid and the frequent problem caused in the hyphae The structure of Dolipore septum was first described by Royall Moore and James McAlear in 1962 Dolipore septum

15. Types of Dolipore Septum peroxisome-derived

16. Types of Dolipore Septum

17. A clamp connection is a hook like structure formed by growing hyphal cells of certain fungi belonging to the class Basidiomycetes It ensures that each cell has a compatible pair of nuclei It helps to create genetic variation in sexually reproducing species Clamp connection is seen in all Basidiomycota fungi but is rarely seen in Rust fungi Clamp Connection

18. Steps in Clamp Connection Terminal cell of hypha . Growth only takes place at hyphal tips Hyphal tip elongating Synchronous division of nuclei and the beginning of hyphal branch that will become the clamp connection. Once nucleus migrates into the new clamp Septum forms at base of the clamp trapping nucleus. Two nuclei of different strains migrate to the hyphal tip, while other nucleus migrates away from the tip Septum forms below clamp forming new cell at hyphl tip. Fusion of the clamp to the adjacent cell releases nucleus of different strain to the adjacent cell Then, both the terminal and subterminal are binucleate , each with a compatible pair of nuclei

19. Fungal hyphae growth Basidiomycota fungi consist of hyphae , which are thread-like structures that make up the fungal body. The first step in the formation of a clamp connection is the growth of hyphae Formation of a septum As the hyphae grow, they develop septa, which are cross-walls that separate individual hyphal cells. The septa have pores that allow cytoplasmic and organelle movement between adjacent hyphal cells Various Steps in Clamp Connection

20. Initiation of nuclear division Within a hyphal cell, nuclear division occurs. The nucleus undergoes mitosis, resulting in the formation of two daughter nuclei. Formation of a clamp connection After nuclear division, a specialized structure called a clamp connection is formed in Basidiomycota fungi. The clamp connection develops at the base of the septum, near the original nucleus Various Steps in Clamp Connection

21. Extension of the clamp connection The clamp connection extends from the base of the septum into the adjacent hyphal cell. It grows in a spiral-like manner and forms a bridge connecting the two hyphal cells Transfer of nuclei Once the clamp connection is established, one of the daughter nuclei from the original hyphal cell moves through the clamp connection and enters the adjacent hyphal cell. This process ensures that both hyphal cells receive a complete set of nuclei Various Steps in Clamp Connection

22. Cell wall reinforcement As the clamp connection matures, the cell walls surrounding it undergo reinforcement. This reinforcement helps stabilize the clamp connection and prevent its breakage Continued growth and branching With the successful formation of the clamp connection, both hyphal cells continue to grow and branch, contributing to the overall expansion and development of the fungal mycelium. Various Steps in Clamp Connection

23. The life cycle of basidiomycetes has primary, secondary and tertiary mycelium . They produce both haploid and dikaryotic mycelia , with the dikaryotic phase being dominant. They generally reproduce sexually by forming basidiospores on a basidium . In the basidium , nuclei of two different mating strains fuse ( karyogamy ), giving rise to a diploid zygote that then undergoes meiosis . The haploid nuclei migrate into four different chambers appended to the basidium , and then become basidiospores . Life cycle of Basidiomycetes

24. Life cycle of Basidiomycetes

25. Each basidiospore germinates and generates monokaryotic haploid hyphae that is called a primary mycelium . Mycelia of different mating strains combine to produce a secondary mycelium that contains haploid nuclei of two different mating strains. This forms the dominant dikaryotic stage of the basidiomycete life cycle and each cell in this mycelium has two haploid nuclei, which will not fuse until formation of the basidium . Later, the secondary mycelium generates a basidiocarp (a fruiting body). The basidiocarp bears the developing basidia on the gills under its cap. Life cycle of Basidiomycetes

26. Sexual Reproduction of Basidiomycetes Sexual reproduction in Basidiomycota takes place in the fruiting body, in specialized structures called basidia The basidia is itself formed by plasmogamy between mycelia from two different spores Plasmogamy results in binucleate hyphae , that is, hyphae with two types of nuclei, one from each parent In the gills of the fruiting body, some cells undergo fusion of these two nuclei Soon after fusion, meiosis takes place, resulting in four haploid nuclei The nuclei then migrate to the terminus of the basidium and form four individual projections These projections are then separated by cell walls to become spores

27. Basidiomycota reproduce asexually by either budding or asexual spore formation Budding occurs when an outgrowth of the parent cell is separated into a new cell. Any cell in the organism can bud. The septae of terminal cells become fully defined, dividing a random number of nuclei into individual cells The cell walls then thicken into a protective coat. The protected spores break off and are disbursed. Vegetative Reproduction of Basidiomycetes

28. Asexual reproduction It takes place by chlamydospores , that are formed rarely during unfavourable condition . Terminal or intercalary chlamydospores are developed on dikaryotic mycelium, which on germination during favou­rable condition produce dikaryotic mycelium.

29. Sexual spore- Basidiospores A basidiospore  is a reproductive spore  produced by  Basidiomycete  fungi Basidiospores typically each contain one haploid nucleus  that is the product of meiosis, and they are produced by specialized fungal cells called  basidia Four basidiospores develop on appendages from each basidium , of which two are of one strain and the other two of its opposite strain Basidiospores of Agaricus bisporus

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