TOPIC 6
FUNGI
I. CHARACTERISTICS OF KINGDOM
II. DIVISION CHYTRIDIOMYCOTA
III. DIVISION ZYGOMYCOTA
IV. DIVISION ASCOMYCOTA
V. DIVISION BASIDIOMYCOTA
VI. IMPERFECT FUNGI
VII. ECOLOGICAL ROLES
I. CHARACTERISTICS OF KINGDOM
A. UNICELLULAR OR MULTICELLULAR
B. CHEMOHETEROTROPHS
1. SAPROBES OR PARASITES
2. FREE-LIVING OR SYMBIOTES
3. NUTRITION THRU ABSORPTION
C. NONMOTILE AT ALL LIFE STAGES CELLS GENERALLY LACK FLAGELLA
D. CELL WALLS OF CHITIN
E. VEGETATIVE BODY = HYPHAE
F. REPRODUCTION
INVOLVES ASEXUAL & SEXUAL SPORES
PRODUCED IN SPECIALIZED HYPHAL UNITS
G. HYPHAE & SPORES = MAINLY HAPLOID
DIPLOID STAGES = TRANSIENT
DISPLAY GENETIC HETEROGENITY
FUNGAL HYPHAE
(SINGULAR = HYPHA = "WEB")
CELLULAR FILAMENTS
DIVIDED BY CROSS WALLS (SEPTA) OR MULTINUCLEATE (COENOCYTIC)
MAT OF HYPHAE = MYCELIUM
SPECIALIZED HYPHAL TIP FOR PENETRATING CELLS = HAUSTORIUM
GENETIC HETEROGENITY IN FUNGI
DURING VEGETATIVE GROWTH MYCELIUM MAY FORM FROM FUSION OF
2 GENETICALLY DISTINCT HAPLOID HYPHAE
DURING SEXUAL CYCLE
SYNGAMY (ZYGOTE FORMATION)
PARTITIONED AS:
PLASMOGAMY = FUSION OF CYTOPLASM FORMATION OF DIKARYON (1n + 1n)
KARYOGAMY = FUSION OF NUCLEI ( = > 2n)
II. DIVISION CHYTRIDIOMYCOTA
CHYTRIDS
UNICELLULAR & MULTICELLULAR
AQUATIC SAPROBES & PARASITES
LINKS TO OTHER FUNGI
ABSORPTIVE NUTRITION
CELL WALLS OF CHITIN
MOLECULAR GENETICS & BIOCHEMISTRY
KEY DIFFERENCE LIFE STAGE (ZOOSPORE) WITH FLAGELLUM
III. DIVISION ZYGOMYCOTA
600 SPECIES
"MOLDS"
SAPROBES, SYMBIOTES, PARASITES
MYCORRHIZAE
TERRESTRIAL, SOIL, DECAYING PLANT & ANIMAL MATERIALS
HYPHAE = MULTINUCLEATE, COENOCYTIC
EXAMPLES
RHIZOPUS = BLACK BREAD MOLD
PILOBUS = DUNG CANON
ENTOMOPHTHORA = INSECT PARASITE
III. DIVISION ZYGOMYCOTA
RHIZOPUS LIFE CYCLE
POOR CONDITIONS = SEXUAL
REPRODUCTION
HYPHA OF 2 MATING TYPES FUSE
(PLASMOGAMY; 1n + 1n)
DIKARYOTIC ZYGOSPORANGIUM
RESISTANT RESTING STAGE
CONDITIONS IMPROVE = KARYOGAMY = > ZYGOTE (2n) FORMS
MEIOSIS = > SPORANGIUM = > HAPLOID SPORES
SPORE = > MYCELIUM
CONTINUOUS GOOD CONDITIONS = ASEXUAL REPRODUCTION
SPORANGIUM = > HAPLOID SPORES = > MYCELIUM (1n)
IV. DIVISION ASCOMYCOTA
60,000 SPECIES
"SAC FUNGI"
UNICELLULAR & MULTICELLULAR
YEASTS, CUP FUNGI, TRUFFLES,
ERGOTS
SAPAROBES, SYMBIOTES, PARASITES
MYCORRHIZAE
MOST LICHENS
EXAMPLES
SARCOSCYPHA = CUP FUNGUS
SACCHAROMYCES = BAKER’S & BREWER’S YEAST
TUBER = TRUFFLE
MORCHELLA = MOREL
DUTCH ELM DISEASE FUNGUS
RYE ERGOT
IV. DIVISION ASCOMYCOTA
SARCOSCYPHA LIFE CYCLE
SEXUAL REPRODUCTION
HYPHA OF 2 MATING TYPES FUSE
(PLASMOGAMY; 1n + 1n)
DIKARYOTIC ASCOGONIUM
FORMS DIKARYOTIC ASCOCARP
FORMS DIKARYOTIC ASCI (SACS)
ASCUS = SITE OF KARYOGAMY
ZYGOTE (2n) = > MEIOSIS = > ASCOSPORES (1n)
ASCOSPORE = > MYCELIUM (1n)
ASEXUAL REPRODUCTION
NAKED CONIDIA (HAPLOID SPORES) = > MYCELIUM (1n)
V. DIVISION BASIDIOMYCOTA
25,000 SPECIES
"CLUB FUNGI"
UNICELLULAR & MULTICELLULAR
MUSHROOMS, SHELF FUNGI, RUSTS, SMUTS
SAPROBES, SYMBIOTES & PARASITES
MYCORRHIZAE
SOME LICHENS
IMPORTANT DECOMPOSERS OF WOOD
EXAMPLES
GILLED & SPONGY MUSHROOMS
PUFFBALLS
PHALLUS = STINKHORNS
CORN SMUT
WHITE PINE & WHEAT RUSTS
V. DIVISION BASIDIOMYCOTA
CORTINARIUS MUSHROOM LIFECYCLE
SEXUAL REPRODUCTION
HYPHA OF 2 MATING TYPES FUSE
(PLASMOGAMY; 1n + 1n)
LONG-LIVED DIKARYOTIC MYCELIUM
DIKARYOTIC BASIDIOCARP
FORMS DIKARYOTIC BASIDIA
BASIDIUM = SITE OF KARYOGAMY
ZYGOTE (2n) = > MEIOSIS = > BASIDIOSPORES (1n)
BASIDIOSPORE = > MYCELIUM (1n)
VI. IMPERFECT FUNGI
ARTIFICIAL GROUPING OF SPECIES
"MOLDS" = HYPHAL MATS
SAPROBES & PARASITES
SEXUAL REPRODUCTION HAS NEVER BEEN OBSERVED
ASEXUAL SPORES ONLY
MANY ARE PROBABLY ASCOMYCOTA
EXAMPLES
PENICILLIUM
ARTHROBOTRYS = PREDATORY FUNGUS
VII. ECOLOGICAL ROLES OF FUNGI
LICHENS
COMPOSITE "ORGANISM"
SYMBIOTIC ASSOCIATION
(MUTUALISM)
FUNGUS = USUALLY ASCOMYCETE,
SOMETIMES BASIDIOMYCETE
PLUS A GREEN ALGA OR CYANOBACTERIUM
FUNGUS = OBLIGATE RELATION (ONLY IN LICHEN)
ALGA = OFTEN FACULTATIVE (CAN BE FREE-LIVING)
FUNGUS ROLE
CREATES SHELTERED ENVIRONMENT
COLLECTS & ABSORBS WATER & MINERALS FROM ATMOSPHERE & SUBSTRATE
PRODUCES PROTECTIVE PIGMENTS
PRODUCES PROTECTIVE TOXINS
ALGA ROLE
SHARES PHOTOSYNTHETIC PRODUCTS
FIX NITROGEN (CYANOBACTERIA)
FUNGUS & ALGA REPRODUCE SEPARATELY OR
AS ASEXUAL UNIT OF FUNGAL HYPHAE & ALGAL CELL = SOREDIA
VII. ECOLOGICAL ROLES OF FUNGI
MYCORRHIZAE
"FUNGUS ROOTS"
SYMBIOTIC RELATIONSHIP BETWEEN FUNGUS & PLANT ROOTS
PLANT PROVIDES
FAVORABLE HABITAT
PHOTOSYNTHETIC PRODUCTS
FUNGUS PROVIDES
INCREASED ABSORPTIVE SURFACE
WATER
MINERALS
GROWTH FACTORS
ANTIBIOTICS
ECTOMYCORRHIZAE
EXTERNAL HYPHAL MANTLE SHEATHES OUTER ROOT SURFACE.
HYPHAE EXTEND INTERNALLY BETWEEN PLANT CELLS
COMMON IN WOODY PLANTS
USUALLY BASIDIOMYCETE
ENDOMYCORRHIZAE
FINE HYPHAL EXTENSION FROM ROOT TO SOIL
HYPHAE PIERCE PLANT CELL
WALLS & GROW WITHIN INVAGINATIONS OF PLANT CELL MEMBRANES
90% OF VASCULAR PLANT SPECIES
USUALLY ZYGOMYCETES
TOPIC 6 FUNGI
READINGS: Pages 574 - 587; 724 - 725
FIGURES: 31.1; 31.2; 31.3; 31.4; 31.5; 31.6; 31.7; 31.8; 31.9; 31.10; 31.12; 31.13; 31.14; 31.15; 37.12
GLOSSARY - TOPIC 6 - FUNGI
Ascus, ascocarp, ascogonium, Ascomycota, ascospores, basidium, basidiocarp, Basidiomycota, chemoheterotroph,chitin, Chytridiomycota, chytrids, club fungi, coenocyte, Deuteromycota, dikaryon, ectomycorrhizae, endomycorrhizae, haustoria, hypha, imperfect fungi, karyogamy, lichen, mold, mutualism, mycelium, mycorrhyzae, plasmogamy, sac fungi, saprobe, septum, soredia, sporangium, yeast, zoospore, Zygomycota, zygosporangium.