Chapter 31 - Fungi IV. Kingdom Fungus A. Estimated 1.5 million species B. Greek, mycos, fungi (mycelium, mycorrhizae, etc…) C. Some are single-celled (in general known as yeast), while most are complex multicellular D. Fungi are heterotrophs that absorb food after digesting with enzymes they secrete outside their body called exoenzymes hyphae Fig. 17.16

Chapter 31 - Fungi IV. Kingdom Fungus E. Types - 1. Saprophytes (saprobes, decomposers) - Break down and absorb nutrients from non-living organic material like a fallen log, dead animals and organismal waste (feces, etc…) Fig. 17.16

Chapter 31 - Fungi IV. Kingdom Fungus E. Types - 2. Parasitic / Pathogens - Take nutrients from living cells, some pathogenic – 80% of plant diseases caused by fungus. “Athletes Foot” Blithe Only 50 out of the known 100,000 fungal species are parasites of animals and these do relatively little damage.

Chapter 31 - Fungi IV. Kingdom Fungus E. Types - 3. Mutualistic symbionts - mycorrhizae mycorrhizael hyphae Fig. 17.16

Chapter 31 - Fungi IV. Kingdom Fungus F. Body Structure 1. Multicellular fungus - Hyphae - Network of tiny filaments making up body of fungus - Cell walls are made of… Chitin = polysaccharide of modified glucose also found in exoskeletons of insects and crustaceans (arthropods) - Mycelium (plural, mycelia) – entire interwoven mass of hyphae - High surface area to volume ratio, efficient feeding - 1ml of soil may contain 1km of hyphae - Like plants, hyphae need to GROW through environment Fig. 17.16

Chapter 31 - Fungi IV. Kingdom Fungus F. Body Structure Septa pores can be large enough to allow nuclei to move through 1. Multicellular fungus - Structure of Hyphae a. Septate hyphae - Most fungi have hyphae divided into cells by septa (crosswalls) with large pores for sharing material b. Coencytic hyphae – continuous cytoplasm with many, many nuclei due to repeated mitosis without cytokinesis similar to slime molds. Fig. 17.16

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 1. Produce spores either sexually or asexually - Carried by wind or water Septa pores can be large enough to allow nuclei to move through - We see this when we leave food out or in fridge too long…spores are everywhere in the air…. Puffball mushroon exploding releasing trillions of spores

Chapter 31 - Fungi Spores vs Gametes Spore Gametes Cell or cell-like structure involved in asexual reproduction May be adapted for dispersal and/or survival in unfavorable conditions Part of life cycle of many Septa pores can be large enough to allow nuclei to move through - plants - fungi - algae/protozoan (protists) Gametes Cells of sexual reproduction Alternation of Generation in Plants

Chapter 31 - Fungi Questions 1. The “root-like” structure of a multicellular fungal organism. 2. Mycellium – define. 3. Spore vs. Zygote – similarities and differences Septa pores can be large enough to allow nuclei to move through 4. Kingdoms of life that have evolved to utilize spores to reproduce. 5. Ploidy of mycellium. 6. Any single-celled fungus. 7. When a single cell fungus reproduces by mitotic cell division, but new cell pinches off the parent cell and is smaller to begin with.

Nuclei of hyphae (mycellium) and spores are haploid!! Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: - Many, but not all reproduce both sexually and asexually. Some do one or the other. Septa pores can be large enough to allow nuclei to move through Start here Nuclei of hyphae (mycellium) and spores are haploid!!

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi General life cycle of fungus - Many, but not all reproduce both sexually and asexually. Some do one or the other. Septa pores can be large enough to allow nuclei to move through - nuclei of hyphae and spores are haploid. Specific Example you need to know from the Ascomycota phylum - The five major fungi phyla – I would not memorize these…

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: Sexual reproduction Septa pores can be large enough to allow nuclei to move through A. Plasmogamy. Very much like Fertilization of gametes Fusion of two cells, a plus (+) and a minus (-), resulting in the combining of the cytoplam (hence plasmogamy). The nuclei do not fuse yet and therefore the cell is dikaryotic (two nuclei).

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: Sexual reproduction Septa pores can be large enough to allow nuclei to move through A. Plasmogamy. - Begins when two distinct mycelia of different mating types (+ and -) secrete pheromones that bind to receptors on each others surfaces. - Hyphae then grow toward each other using mitotic cell division (they follow the pheromone) and fuse those cells that meet from the + and – will fuse = plasmogamy.

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: Sexual reproduction Septa pores can be large enough to allow nuclei to move through A. Plasmogamy. In the case of ascomycetes, the minus (-) cells move toward the plus (+) cell hyphae, bind, and then fuse (plasmogamy) forming a dikaryotic cell known as an ascus.

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: Sexual reproduction Septa pores can be large enough to allow nuclei to move through A. Plasmogamy. B. Karyogamy Fusion of the two nuclei of the dikaryotic cell forming a diploid cell…the ZYGOTE (could occur hours, days or years later). This is similar to a sperm fusing with an ovum. Both haploid followed by plasmogamy, then karyogamy to form the zygote!!

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: Sexual reproduction Septa pores can be large enough to allow nuclei to move through A. Plasmogamy. B. Karyogamy C. Meiosis - Meiosis follows karygomy restoring haploid mycelium that will produce spores. Specifically in the ascomycotes, meiosis occurs, but not cytoplasmic division resulting in a four haploid nucleus cell.

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: Sexual reproduction Septa pores can be large enough to allow nuclei to move through A. Plasmogamy. B. Karyogamy C. Meiosis D. Mitosis - Mitosis of the haploid cells will produce spores of the (+) and (-) types. In the ascus, mitosis occurs resulting in an eight haploid nucleus cell (ascus). Cell walls form around the nuclei turning them into spores (ascospores)

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: Sexual reproduction Septa pores can be large enough to allow nuclei to move through A. Plasmogamy. B. Karyogamy C. Meiosis D. Mitosis E. Germination - The (+) and (-) spores grow by mitotic cell division to form new mycelia

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: ASexual reproduction Septa pores can be large enough to allow nuclei to move through - Minus (-) Mycelia (haploid) will use mitotic cell division to make spores and these spores will become new mycelia. Conidia = Asexual spores of ascomycetes

Chapter 31 - Fungi IV. Kingdom Fungus G. Life cycle of fungi 2. General life cycle of fungus: Molds - Any multicellular fungus that can reproduce rapidly and asexually. It is a general term. Many of these fungi can reproduce sexually, but mold refers only to the asexual stage. Septa pores can be large enough to allow nuclei to move through Yeast - Reproduce predominantly asexually not by using spores, but by budding, a type of simple form of cell division. Sometimes they reproduce sexually.

Chapter 31 - Fungi IV. Kingdom Fungus H. Fungi Evolved from a single-celled flagellated protists The five major phyla of fungi: Septa pores can be large enough to allow nuclei to move through

Chapter 31 - Fungi IV. Kingdom Fungus H. Fungi Evolved from a single-celled flagellated protists 4. Ascomycetes - 32,000 species Bread m - Production of sexual spores in saclike asci - Therefore commonly called sac fungi - Vary from unicellular yeast including bread/beer/wine making yeast (Saccharomycetes cerevisiae) to cup fungi and morels - Consist of some of most deadliest plant pathogens making them relevant to agriculture - More than 40% are lichens – mutualistic relationship between fungi and unicellular chlorophytes (green algae) or with cyanobacteria. - Others form mycohorrhizae Lichen growing on a tree:

Chapter 31 - Fungi IV. Kingdom Fungus H. Fungi Evolved from a single-celled flagellated protists 4. Ascomycetes Lichen: A mutualistic relationship between: Bread m 1. ascomycete fungus and green algae or 2. Ascomycete fungus and cyanobacteria. The algae will reproduce asexually. - Algae/cyanobacteria do photosyn and produce organic compounds for fungus, while fungus provides place to live as well as water and minerals obtained mostly from airborne dust or rain – why they can grow on rock ( hence pioneer species in primary succession).