CZ.1.07/2.2.00/

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1 Zvyšování konkurenceschopnosti studentů oboru botanika a učitelství biologie CZ.1.07/2.2.00/ B. Mieslerová, A. Lebeda, (KB PřF UP v Olomouci)

2 REPRODUCTION OF FUNGI Asexual reproduction Sexual reproduction ASEXUAL REPRODUCTION The ability to reproduce asexually is common to almost all fungi. 1. Bud formation in yeasts 2. Fragmentation Any mycelium that is fragmented or disrupted, provided that the fragment contains the equivalent of the peripheral growth zone, can grow into a new colony. 3. Sporulation Most important type of asexual reproduction of fungi Responsible for the production of large numbers of spores.

3 SPORULATION Asexual spores are formed after mitosis in anamorphic phase of the fungal life cycle There can be more than one mitosporic state for each species of fungus, and in some cases the mitosporic state of very different species can look very similar. Sexual spores are formed after meiosis in teleomorphic phase of the fungal life cycle Characteristics of this phase of the life cycle are much more stable

4 Asexual reproductive structures of main fungal groups Group Myxomycota Oomycota Chytridiomycota Zygomycotina Ascomycotina Deuteromycotina Basidiomycotina Asexual spores None Zoospores in sporangia Zoospores in sporangia Sporangiospores in sporangia Yeast buds, conidia in conidiophores Conidia in conidiophores Aeciospores urediniospores, conidias

5 ASEXUAL REPRODUCTION IN OOMYCOTA Asexual reproduction is by the production of motile zoospores in sporangia, with a one or two flagella, one of them with mastigonemata in sporangia. Sometimes whole sporangium germinates producing germ tube similarly as conidium Zoosporangium Phytophthora palmivora with zoosporas Two flagella, one with mastigonemata

6 Sporangiophore characteristics of five genera of Peronosporales

7 ASEXUAL REPRODUCTION IN CHYTRIDIOMYCOTA Very simple in structure and may only consist of a single cell, perhaps with rhizoids to anchor it on to a substrate. Asexual reproduction is by the production of motile zoospores, with a single, posterior flagellum, in sporangia. Zoosporangium Uniflagellate zoospora

8 ASEXUAL REPRODUCTION IN ZYGOMYCOTINA Zygomycete fungal mycelium is coenocytic Creating of sporangium with columela The large sporangia can contain up to 100,000 spores Sporangium with nonmotile spores

9 Many species with smaller, specialized sporangia, called merosporangia and some are almost conidial, forming single spored sporangia (double spore wall) Order Zoopagales sporangia that break up at maturity, looking rather like the thallic-arthric conidia of some ascomycetes and basidiomycetes

10 ASEXUAL REPRODUCTION IN THE ASCOMYCOTINA (AND DEUTEROMYCOTINA) As asexual reproduction is sometimes the only form of reproduction seen in some fungi Conidia are formed on conidiophores by blastic process In some groups the conidiophores (the structures that bear the conidia) are aggregated forming specialised structures (pycnidia, acervuli, coremia and sporodochia)

11 7 group of spores based on morphology

12 DIFFERENT METHODS OF CONIDIAL DEVELOPMENT A. Thallic development: no enlargement of the conidium initial B.Holoblastic development: all layers of wall form a conidium which is larger than the conidiogenous cell C,D. Enteroblastic development: Only inner wall layers of the conidiogenous cell are involved in conidium formation C. tretic D. phialidic: the conidiogenous cell is a phialide. The wall of the phialide is not continuous with the wall surrounding the conidium

13 DIFFERENT METHODS OF CONIDIAL DEVELOPMENT Thallic conidiogenesis Blastic-phialidic conidiogenesis Blastic conidiogenesis

14 Septoria apiicola Pycnidium Acervulus Colletotrichum graminicola

15 Penicillium Coremium Single conidiophores Stigmina Sporodochium

16 ASEXUAL REPRODUCTION IN BASIDIOMYCOTINA Not very often, in most of groups missing, partly by conidia and in some highly specialised groups (Uredinales) creating various types and shapes Telia with teliospores Aecia with aeciospores Uredia with uredinospores

17 SEXUAL REPRODUCTION To achieve sexual reproduction it is necessary to have two mating type haploid nuclei (n + n), or a diploid (2n) nucleus Two haploid nuclei fuse to form a diploid first, then the nuclei undergo meiosis, which is the reduction division that potentially brings about variation These event are followed by the formation of spores, which in most cases are resting spores that can withstand adverse conditions.

18 TYPES OF SEXUAL REPRODUCTION Isogamy - fusion of morphologically identical gametes (Chytridiomycota, Myxomycota). Anisogamy fusion of the morphologically different gametes (Chytridiomycota) Gametangiogamy fusion of the male and female gametangia (Zygomycotina, Ascomycotina) Oogametangiogamy fusion of the male gametangium and female oogonium (Oomycota) Gameto- gametangiogamy fusion of the gametangium (female) and gamete (male) example spermatisation (Ascomycotina) Somatogamy fusion of the somatic structures (Basidiomycotina)

19 Sexual process of main fungal groups Group Sexual process Myxomycota Oomycota Chytridiomycota Zygomycotina Ascomycotina Deuteromycotina Basidiomycotina Isogamy Oogametangiogamy Isogamy, anisogamy, somatogamy, oogametangiogamy Gametangiogamy Gametangiogamy, gameto-gametangiogamy None Somatogamy, gameto-somatogamy (rusts)

20 SEXUAL REPRODUCTION IN MYXOMYCOTA Isogamy (copulation of myxomonadas or myxamoebas) following karyogamy and forming sporocarps with sporas Two myxoamoebae During sexual reproduction myxoamoebae will also function as gametes (isogametes)

21 Life cycle of Myxomycota

22 Life cycle of Plasmodiophoromycota

23 SEXUAL REPRODUCTION IN OOMYCOTA Oogametangiogamy fuse of oogonium ( ), anteridium ( ), forming oospora (one or more)

24 Oogonium with one oospora (Bremia lactucae) Oogonium with more oosporas (Saprolegnia sp.)

25 Life cycle of Plasmopara viticola

26 SEXUAL REPRODUCTION IN CHYTRIDIOMYCOTA After gametic or somatic fusion of two different mating types production of diploid zygote (isogamy, anisogamy, somatogamy) The resulting spore (zygote) may germinate to produce a diploid vegetative thallus or it may undergo meiosis to produce a haploid thallus The diploid thallus can also produce resting sporangia in which meiosis occurs, generating haploid zoospores that germinate to produce haploid vegetative thallus

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29 SEXUAL REPRODUCTION IN ZYGOMYCOTINA Reproduce sexually by the physical blending - fusion or conjugation of morphologically similar gametangia (Gametangiogamy) to form a diploid zygosporangium. Zygosporangia usually develop thick walls, and act as resting spores. Meiosis occurs, producing sporangium with haploid spores HOMOTHALLIC - describes fungi in which a single strain can undertake sexual reproduction; self-compatible HETEROTHALLIC - describes fungi in which two genetically distinct but compatible mycelia must meet before sexual reproduction can take place Progametangia Copulation of gametangia Formation of a zygospora

30 Life cycle of Rhizopus nigricans

31 SEXUAL REPRODUCTION IN ASCOMYCOTINA There are specialized organs of hyphal fusion (ascogonium with trichogyn ( ) and antheridium ( )) which fuse with each other to form dikaryons (Gametangiogamy) Similarly fusion is possible with ascogonium ( ) and spermatia forming in spermogonia (gameto-gametangiogamy) Most ascomycetes interpolate a dikaryophase, during which the number of pairs of compatible nuclei is multiplied, often enormously, as dikaryotic hyphae (often called ascogenous hyphae) Nuclei in tip cells fuse to produce diploid cell Diploid nucleus undergo meiosis then each progeny nucleus undergo a single mitosis to produce 8 ascospores The asci can be aggregated together in various sorts of fruit body (cleistothecia, perithecia, apothecia, pseudothecia) In yeasts, a single, diploid yeast will undergo meiosis, producing four haploid progeny cells

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33 How operculate asci develop and shoot

34 Life cycle of Podosphaera leucotricha

35 SEXUAL REPRODUCTION IN BASIDIOMYCOTINA Acquisition of two mating types of nuclei by the fusion of compatible mycelium (somatogamy) This creates a dikaryon; maintenance of the dikaryon requires elaborate septum formation during growth and nuclear division Environmental conditions trigger the formation of a fruit body primordium The primordium expands and differentiates to form the large fruit bodies The mycelium within this structure remains as a dikaryon, diploid formation only occurring within the modified hyphal tip called the basidium Meiosis occurs within the basidium, and the four basidiospores are extruded from the tip of the basidium on sterigma

36 Caryogamy, meiosis and basidiospore formation in Basidiomycotina

37 Life cycle of Basidiomycotina

38 Life cycle in rusts (Uredinales)

39 Spermogonia with spermatia and receptive hyphae (gameto-gametangiogamy) Aecia with aeciospores