Chapter 19

Kingdom Fungi and LichensI. Introduction

A. Fungi and Oil Spills

B. Basic Structure of Fungi 1. Hyphae, tubular threads 2. Mycelium, a mass of hyphae

C. Mycology 1. Study of fungi 2. Mycologists • scientists who study fungi

D. Distinctions Between Kingdoms Protoctista and Fungi

1. True Fungi a. Filamentous or unicellular saprobes or parasites b. Two divisions and several classes of fungi

2. Slime Molds (assigned to Kingdom Protoctista)

a. Protist-like characteristics 1) Absence of cell walls 2) Amoeboid movement 3) Ingestion of food particles

b. Fungus-like characteristics 1) Sporangia 2) Spores

II. Kingdom Fungi - The True Fungi A. Division Zygomycota—The Coenocytic True Fungi

1. Habitat a. Organic matter; untreated breads b. Soil (nematode-trapping fungi), dung-fungi

2. Shape • hyphae coenocytic

3. Reproduction—Rhizopus (bread mold)

a. Asexual 1) Sporangiophores grow upright and produce sporangia at

their tips 2) Numerous spores produced in each sporangium

b. Sexual 1) Conjugation of different mating strains

2) Formation of progametangia 3) Gametangia merge, becoming large multinucleate cell 4) Wall develops around cell, forming the zygospore

4. Human and ecological significance of the coenocytic true fungi

a. Food: tempeh and sufu

b. Other uses 1) Pharmaceuticals 2) Industrial alcohols 3) Meat tenderizer 4) Yellow pigment for coloring margarine

B. Division Eumycota—The Non Coenocytic True Fungi

1. Class Ascomycetes—The Sac Fungi

a. Habitat 1) Parasites of many plant hosts • powdery mildews, brown fruit rot, ergot 2) Saprophytes • yeasts, morels, truffles

b. Shape 1) Mycelium septate with pores in septa 2) Unicellular • yeasts

c. Reproduction

1) Asexual a) By means of conidia, externally produced spores b) Yeasts reproduce by budding

2) Sexual a) Involves formation of an ascus b) Male antheridia produced on one hypha, female

ascogonia on other c) Male nuclei migrate into ascogonium d) Ascogenous hyphae formed e) At maturity, pairs of nuclei unite forming 2n

nuclei f) Diploid nuclei undergo meiosis; these nuclei

become nuclei of ascospores g) Ascospores (n) released into air

d. Human and ecological relevance of sac fungi

1) Edible • morels, truffles

2) Ergot of rye • infected rye grain ingested and causes ergotism • St. Anthony’s fire

3) Commercial applications • brewing and baking industries (yeasts)

4) Disease causing agents • Dutch elm disease, chestnut blight, ergot of rye

2. Class Basidiomycetes—The Club Fungi

a. Habitat 1) Saprophytes a) Mushrooms (toadstools) b) Puffballs, earth stars, jelly fungi, stinkhorns

2) Parasites a) Shelf or bracket fungi b) Rusts, smuts

b. Shape 1) Mycelium septate with pores 2) Uninucleate or binucleate stages of mycelium

c. Reproduction 1) Asexual • infrequent, rare

2) Sexual a) Hyphae of mycelium are monokaryotic b) Hyphal cells of compatible mating types may unite,

initiating a new dikaryotic mycelium c) Formation of clamp connection, with one nucleus

migrating into clamp d) Mitosis and formation of crosswalls e) Dikaryotic mycelium may become very dense, forming the button, which may penetrate the surface and expand into the basidiocarp (mushroom) f) Gill of mushroom has numerous basidia g) As each basidium matures, the two nuclei unite, and

then undergo meiosis; the four nuclei become the nuclei of the four basidiospores

d. Examples

1) Shelf (bracket) fungi

2) Puffballs

3) Earth stars

4) Bird’s nest fungi

5) Smuts

6) Rusts

e. Human and ecological relevance of the club fungi 1) Mushroom poisoning a) Fewer than 75 species • Death Angel species very poisonous b) Thioctic acid used as antidote 2) Hallucinatory mushrooms a) Teonanacatl (God's flesh) sacred mushrooms • used by Mayan civilization b) Fly agaric mushrooms 3) Commercial uses a) Black Forest (shiitake) mushrooms i) High nutritional value

• double the nutritional content of commercial mushrooms ii) Lentinacin extract • lowers blood cholesterol • extracts exhibit antiviral activity by inducing formation of

interferon b) Cultivation for food • Agaricus bisporus (commercially grown mushroom) 4) May damage food, leather, paper, wood

3. Class Deuteromycetes—The Imperfect Fungi

a. Features 1) Several disease causing organisms 2) Important in disease control and food processing 3) Sexual reproductive stages not known 4) This is an artificial grouping 5) Examples a) Parasites of protozoans and small animals b) Nematode trappers c) Forms cultivated by ants and termites d) Mycorrhizal fungi

6) Shape • filamentous hyphae 7) Reproduction • by means of conidia

b. Human and ecological relevance of the imperfect fungi

1) Penicillium • antibiotic, penicillin 2) Curing of cheeses • Blue, Camembert, and Roquefort cheese 3) Cyclosporine • immunosuppressive drug used in organ transplants 4) Soy sauce • fermented soybeans (Aspergillus)

5) Diseases a) Aspergillosis • respiratory tract infection b) Athlete's foot c) Ringworm d) White piedra • disease of man's beard 6) Aflatoxin • carcinogenic compound secreted by Aspergillus flavus

III. Lichens A. Features

1. Symbiosis between a fungus and an alga a. Can be viewed as a controlled parasitism of the alga by the

fungus b. About 25,000 species of lichens 2. Grow very slowly 3. May live 4,500 years or more and are very tolerant of extreme

environmental conditions, except for pollution and nuclear radiation

4. Forms a spongy body (thallus) a. Consists of three or four layers of cells or hyphae 1) Upper cortex 2) Algal layer 3) Medulla 4) Lower cortex 5) Rhizines

b. Growth forms 1) Crustose lichens • often brightly colored, crusty patches 2) Foliose lichens • leaf-like thalli 3) Fruticose lichens • thalli branched and cylindrical in shape c. Algal partners • three genera of green algae and one of blue-green

bacterium involved in 90% of lichen species d. Fungal partners • almost all lichens have members of the sac fungi as their

fungal componente. Classification

• lichen species identified according to the fungus present

B. Reproduction

1. Lichens dispersed primarily by asexual means • some produce powdery clusters of hyphae and algae called

soredia

2. Sexual reproduction similar to the sac fungi, except ascocarps produce spores continually for many years

C. Human and Ecological Relevance of Lichens

1. Provide food for lower animals and many large mammals • reindeer and caribou

2. Many have antibiotic properties

3. Dyes extracted from lichen thalli

a. Manufacture of Scottish tweeds and East Indian cotton fabrics

b. Litmus paper dyes (acid-alkaline indicator)

4. Soaps and perfumes scented with lichen extracts

5. Model landscaping • fruticose lichens resemble miniature trees and shrubs, used

for scenery