Fungi Chapter 31

Plantae Fungi Animalia Protista Monera

Kingdom Fungi Uses: medicine food Ecological value: major decomposers About 100,000 species Uses: medicine food Ecological value: major decomposers symbiotic relationships (N2 fixers) Problems: some strains are deadly athletes foot destroy library books destroy crops

Some fungi are pathogens About 30% of the 100,000 known species of fungi are parasites, mostly on or in plants. American elms: Dutch Elm Disease American chestnut: chestnut blight What is DED, and where did it come from? DED is one of the most destructive shade tree diseases that affects elm trees. The disease kills individual branches and eventually the entire tree within one to several years. A fungus and an insect are responsible for DED development. The fungus was introduced to the United States on diseased logs from Europe in the 1930’s. What causes the tree to die from DED? The DED fungus grows and reproduces in the water conducting parts of elm branches and stems. The fungus blocks water movement to tree leaves which causes the leaves to wilt and turn brown. How does the DED fungus get into the tree? The fungus needs help from insects, the elm bark beetles. Elm bark beetles use weakened and diseased trees to reproduce. Beetle offspring emerge from diseased elms and fly to healthy elms to feed. However, before leaving diseased trees, spores of the DED fungus (which are like tiny fungus “seeds”) attach onto them. When these fungus-infested beetles feed on healthy tree branches, they make small wounds in the wood, and the fungus enters the branch directly through these wounds. Once the fungus is in an elm tree, it can move through the root system of a diseased tree into the root system of adjacent healthy elm trees. It can do this because roots of elm trees growing close to each other frequently join or graft to each other. United States Department of Agriculture Forest Service Northeastern Area NA-PR-05-99 Page 2How can I tell if an American elm has DED? Look for leaves that are wilting or yellow and which eventually turn brown. Wilting and leaf color change are symptoms of DED that occur during the spring and summer, but usually start to appear one month after trees leaf out in the spring. Leaves most affected appear at the end of large branches. Dead branches without leaves may indicate previous year’s mortality from DED. In some communities, disease experts make routine elm examinations for DED symptoms. How and why do experts evaluate DED symptoms?Experts examine each tree and estimate the percent of leaves with symptoms and relate this percentage to where symptoms are located. This determines how much disease is in the tree, and it can also indicate whether the fungus infected the tree through joined roots or bark beetle wounds. The most appropriate DED management tactics are based on the amount of disease present. The amount of disease can be described simply as being either minor or major. What are minor amounts of DED in elms and can these elms be treated? Elms with minor DED have few symptoms (less than 10 percent of all leaves) usually located in only one large branch. DED may be eliminated from these trees by pruning out diseased branches and/or injecting chemical fungicide into the base of the trees. If left untreated, however, the amount of disease will increase. What are major amounts of DED in elms and can these elms be treated? Elms with major DED usually have more than 10 percent of all leaves or more than one large branch showing symptoms. Unfortunately trees with major amounts of disease cannot be effectively pruned. Fungicide injection is unlikely to be effective to stop an infection that has occurred through joined roots or which has affected a large portion of the branches. Elms with major amounts of disease will eventually die from the disease, and provide habitat for beetles and fungi that can infect healthy trees. Elms with major DED should be removed as soon as possible. This removal of diseased elms is called sanitation and is crucial to eliminate the spread of both the elm bark beetles and fungus to healthy neighboring elms. Is there hope for the American elm? Yes. If communities practice good sanitation (removal of dead trees), many existing elms will escape DED infection. It is also possible to prune diseased branches and inject individual high-value elms with fungicides to treat and protect them from DED infection. Also, scientists are now testing American elms that may be tolerant or resistant to DED. Combining all of these management tactics provides promise for the continued presence of American elms in our cities and parks. Where can I get more information about DED? The recent publication “How to Identify and Manage Dutch Elm Disease” is now available on the Internet at http://willow.ncfes.umn.edu/ht_ded/ht_ded.htm. Information is also available from your city forester, tree care companies, your local Cooperative Extension Service, or the Forest Service offices listed below. Photographs provided by Dr. R. Jay Stipes, Virginia Polytechnic Institute and State University. For additional information, contact: Linda Haugen USDA Forest Service 1992 Folwell Avenue St. Paul, MN 55108 http://willow.ncfes.umn.edu Alan Iskra USDA Forest Service 180 Canfield Street Morgantown, WV 26505 Phone (304) 285-1553July 1999 Was once one of America's most dominant trees

Some fungi are pathogens Other fungi, such as rusts and ergots, infect grain crops, causing tremendous economic losses each year.

Some fungi are pathogens                                Curse of the Mummy

Some fungi are persistant Athletes Foot

Kingdom Fungi Eukaryotic, absorptive Mostly multicellular (except few, e.g. yeast) Heterotrophic (decomposers & parasitic) Mycelium (body of hyphae)

Kingdom Fungi Firm cell walls (generally of “chitin”) “Spores” as reproductive bodies Unique chromosomes and nuclei Includes molds, yeasts, rusts, and mushrooms

hyphae - the vegetative bodies of most fungi, constructed of tiny filaments mycelium -an interwoven mat of hyphae

Human hair Fungal hypha

Septate hypha: multicellular walls divided by septa Ceonocytic hypha: continuous cytoplasm mass multinucleate no septa

Haustoria: Modified hyphae found in parasitic fungi Function: absorb nutrients from host Some fungi even have hyphae adapted for preying on animals.

Kingdom Fungi Division Chytridiomycota Division Ascomycota Division Basidiomycota Division Zygomycota Division Deuteromycota

? Deuteromycota Fungus-like protist

The four fungal phyla can be distinguished by their reproductive features.

Division Chytridiomycota mainly aquatic. Some are saprobes, while others parasitize protists, plants, and animals. chitinous cell wall flagellated zoospores the most primitive fungi

Division Zygomycota “Zygote fungi” (bread molds) Zygote = “mated” hyphal strands Live in soil, water Some are parasites 600 species

Mated hyphal strands

The zygosporangia are resistant to freezing and drying. When conditions improve, the zygosporangia release haploid spores that colonize new substrates. Pilobolus aiming its spores.

The zygomycete Rhizopus can reproduce either asexually or sexually.

Division Ascomycota “Sac fungi” (truffles, yeast) Beer > 6,000 years Wine > 8,000 years Lichens Decomposers, pathogens “yeast” describes a form of fungi (i.e., non-hyphal) 60,000 species

Division Ascomycota Scarlet cup Morchella truffles

Division Ascomycota Close up of cheese showing blue-green mycelium of Penicillium roqueforti. Roquefort cheese

Yeast

Lichen

Lichen Anatomy

Ascomycetes are characterized by an extensive heterokaryotic stage during the formation of ascocarps.

Division Basidiomycota “Club fungi” (mushrooms) Club-shaped reproductive structure Food Plant diseases 25,000 species

Fairy Ring

The life cycle of a club fungus usually includes a long-lived dikaryotic mycelium.

Division Deuteromycota “Imperfect fungi” (penicillin) Unrelated group Asexual No info on sexual cycle 25,000 species

Penicillin Woops… now Ascomycota

Candida albicans “yeast infection”

Botrytis: “Noble Rot”

Plant-Fungal Relationships Mycorrhizae (“fungus roots”) 90% of tree species have this association Very important to absorption of water and nutrients

Soil surface Plant roots Mycorrhizae Increases s.a. for absorption