Reproduction in fungi

Different types of reproduction in fungi

1. PRESENTED BY … Thakor Maitri M . M.Sc. (Botany) Department of Life Sciences, H.N.G.U., Patan . 1 Reproduction in Fungi

2. Content Introduction Definition & Types of Reproduction. Vegetative Reproduction ¤ fragmentation,fission,budding,sclerotia,rhizomorph . Asexual Reproduction ¤ Endogenous spores ¤ Exogenous spores Sexual Reproduction ¤ Plasmogamy ¤ Karyogamy ¤ Meiosis ¤ Methods of sexual reproduction 2

3. Introduction Definition : Fungi are reproduce with all the characteristics typical of the species and the formation of new individuals. Some of the important methods of reproduction in fungi are as followed : 1. Vegetative reproduction 2. Asexual reproduction 3. sexual reproduction. 3

4. 1.Vegetative Reproduction Vegetative reproduction does not involve the union of nuclei, sex cells (gametes) or sex organs (gamatangia). Vegetative reproduction helps to increase the number of individuals in the populations. Vegetative reproduction in fungi occurs by : Fragmentation Fission Budding Sclerotia Rhizomorphs 4

5. Fragmentation : The mycelium break up into small fragments or pieces and each of which is able to develop into new individuals. This is of two types:(a)accidental:(like a fast flowing water) (b) purposive :(like vegetative rep.) common in filamentous fungi. ( Rhizopus,Aspergillus ) (class- ascomycota, Basidiomycota) Fission : Mature cells are mitotically divided into two daughter cells and rise to new individuals. Occurs in unicellular fungi. ( Yeast) 5

6. Budding : The production of a small new cell from the outgrowth (bud) of a cell it’s called Budding . Pseudo mycelium : Chains of buds , is it. Occurs in unicellular forms such as Yeast. (Class – saccharomyces ). 6

7. Sclerotia : Sclerotia are Pseudo parenchymatous mycelium aggregations. The sclerotia are resistant and parennating bodies so they Survive for many years. Each sclerotium is cushion-like structure of Compact mycelium. The compact mycelium give a rise to new mycelia on the approach of favourable conditions. e.g. Claviceps purpurea , Rhizoctonia solani . Rhizomorph : Modified mycelium, the rope like Rhizomorphs are also resistant to unfavourable conditions, after several years on the approach of favourable conditions they give rise to new mycelia. e.g. Armillaria mellea . 7

8. 2. Asexual Reproduction The asexual reproduction takes place by means of spores , any spores formed are thus mitospores, and not the zygotes or meiospores. Each spore may develop into a new individual. Sporophores : the spores are of diverse type and borne upon special structures, it is .. Pleomorphic / Polymorphic : When the fungus producing more than one types of the spores it’s called it is. Following the spore’s place on the sporangia , there are two types spore in the asexual spores. (A) Endogenous spores (B) Exogenous spores zoospirangium & zoospore of Phytophthora conidiophores & conidia of Penicilium 8

9. (A) Endogenous spores : The spores prodused inside the sporangia are termed the endogenous spores . Sporangium: The endogenous spores are produced within the special spore producing cell it’s called it. Sporangiophores: The sporophores which bear the sporangia on their apices are called the Sporangiophores. Endogenous spores are two types : (a) Aplanospores (b) Zoospores 9

10. (a) Aplanospores : The Aplanospores are non-motile, without flagella and they may be uni / multinucleate. They lack vacuoles. They possess two layered cell walls. • epispore / exospore : The outer thick layer. • endospore : The inner thick layer. e.g. Mucor,Rhizopus Aplanospore of Mucor Rhizopus Aplanospore & cleistothesium of Erysiphe 10

11. (b) Zoospores : Zoospores are motile and they have uni/biflagellate , without any cell wall , uninucleate , vacuolate. Usually kidney shaped or reniform . The flagella are inserted posteriorly or laterally on them. E.g. Albugo, Pythium, Phytophthora and many other lower fungi. Albugo sporangium & zoospores of Phytophthora 11

12. (B) Exogenous spores : The spores produsing externally or exogenously on the terminal ends of sporophores are called the exogenous spores or conidia. Conidiophores : Which part is produced conidia externally on the branched or unbranched it’s called it. The conidia are diverse in their shape and size & also in colour, uni/multi cellular and uni/multi nucleate. The blue-green molds : The conidia of Aspergillus & Penicillium are smoky green coloured so the fungi are called it. In other type of exospores, the sporophores develop in groups and form the specialized structure called the pustules, pycnidia, aecidia, and sporodochia. 12

13. Other types of exospores : conidia of Aspergillus conidia of Cercospora conidia of Colletotrichum conidia of Fusarium conidiophore & conidia of Penicillium 13

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15. 3. Sexual Reproduction Union of two nuclei or gametes of opposite sex , a gamete is unisexual (haploid) it’s called the Sexual reproduction. Deuteromycetes lack sexual reproduction. There are two distinct phases in the life cycle : (1) Haploid phase : (x) number of chromosomes in the nucleus. (2) Diploid phases : (2x) numbers of chromosomes in (a) ends with fertilization, (b) with meiosis. 15

16. Monoecious / homothallic: When both the sex organs or strains occur on the same mycelium, this fungus is said to be Monoecious / homothallic . Dioecious / heterothallic: When the male and female sex organs or plus or minus strains occur separately on different mycelia, this fungus is said to be Dioecious / heterothallic. Isogamy : The morphologically similar identical male and female gametes are called the isogametes and when fusion to each other than it’s called Isogamy . 16

17. Anisogamy : The morphologically dissimilar male and female gamete are called the heterogametes, when they fusion to each other than it’s called Anisogamy . 17

18. Plasmogamy : The fusion of the plasma of the gametes Karyogamy : The fusion of the nuclear of the gametes Karyogamy in lower fungi: There is complete fusion of the nuclei of the two different strained gametes in the sexual union. Dicaryons in higher fungi: The fusion of the two nuclei of different strains is delayed and the pairs of the nuclei, it’s called the Dicaryons. e.g., Ascomycetes & Basidiomycetes . 18

19. Dicaryotic mycelium : The mycelium having such pairs of nuclei is called the Dicaryotic mycelium. Monocaryotic mycelium : Where the mycelium possesses single haploid nucleus of either strain in each cell is called the Monocaryotic mycelium. Meiosis : Zygote immediately undergo meiosis to produce meiospores. After karyogamy reduction division takes places in the diploid nucleus and thus haploid stage is established. 19

20. Methods of Sexual Reproduction The most comman methods of sexul reproduction are as follows : Planogametic copulation Gametangial contact Gametangial copulation Spermatization Somatogamy 20

21. 1)Planogametic copulation : Involve the fusion of two naked gametes . One or both gametes are motile, motile gametes are known as planogametes. Isogamous planogametes : Synchytrium , plasmodiophora…. Anisogamous planogametes : Allomyces Oogamous : Monoblepharis 21

22. 2) Gametangial contact : Found in many lower fungi. ( class- Phycomycetes). In this method two gametangia of opposite sex (oogonium and antheridium ) come in contact and one or more gamete nuclei migrate from the male gametangium (antheridium) to the female gametangium (oogonium). Male nuclei migrate to female gametangium by dissolution of wall. e.g., Aspergillus, Penicillium etc. 22

23. In other species the male nuclei migrate through a fertilization tube. e.g., Pythium , Albugo , Peronospora etc. 23

24. 3) Gametangial copulation : The fusion of the entire contents of two contacting compatible gametangia takes place ( by pore ) e.g., Mucor , Rhizopus , Entomophthora etc. 24

25. 4) Spermatization : In some advanced fungi sex organs are completely absent. Here sexual process is accomplished by minute spore like spermatia and specialized hyphae acting as male and female structure. Spermatia is carried by air, water or insect to the receptive hyphae. Spermatia attached to the trichogyne of receptive hyphae and migrate into the cytoplasm. 25

26. 5) Somatogamy : Sex organs are not prodused. Two Somatic cells take part in sexual function and fuse together. e.g., Morchella , Peziza, Agaricus & many higher fungi. 26

27. Reference 1) A TEXT BOOK OF BOTANY FUNGI Author : B. P. Pandey 2) Fungi and Allied Organisms Author : P. D. Sharma 3) A TEXT BOOK OF BOTANY ( Volume 1 ) Edition : First Edition (2008) Author : N.C. Kumar 4) WWW.slideshare.net 27

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