All Fungi Are Heterotrophic
§ Fungi cannot manufacture their own food
§ Must rely on other organisms for energy
► saprobes, organisms that obtain food from decaying organic matter
parasites, which harm other organisms while living directly on or within them
symbionts that live in close and mutually beneficial association with other species
Fungi as Decomposers
§ Maintain equilibrium by recycling nutrients by breaking down the bodies and wastes
of other organisms
§ Feed by releasing digestive enzymes that break down leaves, fruit, and other organic
material into simple molecules
Fungi as Parasites
§ Fungi can cause disease such as corn smut, which destroys the corn kernels
§ Mildews, which infect a wide variety of fruits, are also fungal
§ Responsible for the loss of approx. 15% of the crops grown in temperate regions
§ Responsible for the loss of approx. 50% of the crops in tropical areas
v Example - wheat rust
affects one of the most important crops grown in North America
w Rusts are caused by a type of basidiomycete that needs two different plants to
complete its life cycle.
w Barberry plants produce the spores that are carried by wind to wheat plants.
w Spores germinate and infect wheat plants.
w This rust produces a second type of spore that infects other wheat plants spreading
w Tough black spores are produced late in the season and survive over winter.
w In spring, they go through a sexual phase, produce spores that infect barberry
v Understanding the life cycle helps to slow the spread by destroying the barberry
§ Athlete's foot is caused by a deuteromycetes infecting the toe area producing
a red, inflamed sore from which spores are released and can spread from person to person
§ This same fungus infects other areas, such as the skin of the scalp, producing
a red scaling sore known as ringworm
§ Candida albicans, a yeast, may produce thrush, a painful mouth infection or infections of the female reproductive
§ Cordyceps is a fungus that infects grasshoppers in rain forests of Costa Rica.
§ Microscopic spores become lodged in the grasshopper and produce enzymes that slowly
penetrate the insect's tough external skeleton.
§ Spores multiply in the insect's body, digesting all its cells and tissues until
the insect dies.
§ Some fungi form a symbiotic relationship in which both partners benefit.
§ Lichens are not a single organism but rather a symbiotic association between a fungus
and a photosynthetic organism.
§ Fungi in lichens are usually ascomycetes or basidiomycetes
§ Photosynthetic organisms are either green algae or a cyanobacterium, or both
§ Extremely resistant to drought and cold.
§ Grow in places where few other organisms can survive--dry, bare rock in deserts
and on the tops of mountains.
§ Algae or cyanobacteria carry out photosynthesis providing the fungus with energy
§ Fungus provides algae or bacteria with water and minerals collected from the sunlight
§ Lichens are also sensitive to air pollution, and are among the first organisms
to be affected when air quality deteriorates.
§ Mycorrhizae is a mutualist association between plant roots and fungi.
§ 80% of all plant species form mycorrhizae with fungi
§ Tiny hyphae of the fungi aid plants in absorbing water and minerals by increasing
the surface area of the root system
§ Plants provide the fungi with the products of photosynthesis