<< Chapter < Page Chapter >> Page >
By the end of this section, you will be able to:
  • Describe fungal parasites and pathogens of plants
  • Describe the different types of fungal infections in humans
  • Explain why antifungal therapy is hampered by the similarity between fungal and animal cells

Parasitism describes a symbiotic relationship in which one member of the association benefits at the expense of the other. Both parasites and pathogens harm the host; however, the pathogen causes a disease, whereas the parasite usually does not. Commensalism occurs when one member benefits without affecting the other.

Plant parasites and pathogens

The production of sufficient good-quality crops is essential to human existence. Plant diseases have ruined crops, bringing widespread famine. Many plant pathogens are fungi that cause tissue decay and eventual death of the host ( [link] ). In addition to destroying plant tissue directly, some plant pathogens spoil crops by producing potent toxins. Fungi are also responsible for food spoilage and the rotting of stored crops. For example, the fungus Claviceps purpurea causes ergot, a disease of cereal crops (especially of rye). Although the fungus reduces the yield of cereals, the effects of the ergot's alkaloid toxins on humans and animals are of much greater significance. In animals, the disease is referred to as ergotism. The most common signs and symptoms are convulsions, hallucination, gangrene, and loss of milk in cattle. The active ingredient of ergot is lysergic acid, which is a precursor of the drug LSD. Smuts, rusts, and powdery or downy mildew are other examples of common fungal pathogens that affect crops.

Part A show fungal parasites on grapefruit. Part B show fungal parasites on a zinnia. Part C show fungal parasites on a sheaf of barley. Parts D show fungal parasites on grapes.
Some fungal pathogens include (a) green mold on grapefruit, (b) powdery mildew on a zinnia, (c) stem rust on a sheaf of barley, and (d) grey rot on grapes. In wet conditions Botrytis cinerea, the fungus that causes grey rot, can destroy a grape crop. However, controlled infection of grapes by Botrytis results in noble rot, a condition that produces strong and much-prized dessert wines. (credit a: modification of work by Scott Bauer, USDA-ARS; credit b: modification of work by Stephen Ausmus, USDA-ARS; credit c: modification of work by David Marshall, USDA-ARS; credit d: modification of work by Joseph Smilanick, USDA-ARS)

Aflatoxins are toxic, carcinogenic compounds released by fungi of the genus Aspergillus . Periodically, harvests of nuts and grains are tainted by aflatoxins, leading to massive recall of produce. This sometimes ruins producers and causes food shortages in developing countries.

Animal and human parasites and pathogens

Fungi can affect animals, including humans, in several ways. A mycosis    is a fungal disease that results from infection and direct damage. Fungi attack animals directly by colonizing and destroying tissues. Mycotoxicosis is the poisoning of humans (and other animals) by foods contaminated by fungal toxins (mycotoxins). Mycetismus describes the ingestion of preformed toxins in poisonous mushrooms. In addition, individuals who display hypersensitivity to molds and spores develop strong and dangerous allergic reactions. Fungal infections are generally very difficult to treat because, unlike bacteria, fungi are eukaryotes. Antibiotics only target prokaryotic cells, whereas compounds that kill fungi also harm the eukaryotic animal host.

Questions & Answers

What is biology
Zainab Reply
what is a catylist to be honest
Hilma Reply
what is a biological catalyst
Hilma
what is a biological catalyst
Hilma
Are materials which are found in the living organisms to increase the rate of chemicals reaction
Aguer
what is d different between microscope and light microscope
samuel Reply
what are the importances of biology
Shatritah Reply
fungi is it unicellular
Lemaa Reply
what is cell
Samuel Reply
cell is the building block of life,
Semret
Cell is the structural and functional unit of life....
Soumili
what is cell sap
lubaya Reply
what do female humans release when they masturbate
Hwebuma Reply
what are genetics
Mercy Reply
Genetics is the branch of science that deals with the study of inheritance and variation.
Evans
Genetics is the branch of biology that deals with the study of variation
KIHEMBO
Genetic is the study of how different qualities are called strait, pass down from parents to child
Timileyin
y are my not division of animal here
Hyacinth Reply
what is ornithology
Shatritah
Is the scientific study of birds
Evans
what is biology
Ada Reply
nidhi
Nidhi
is a science that deal with study of living organisms
Santino
what is platypus
Nabil
What is Homeostasis?
ibrahim
nidhi
Nidhi
what is mildew
Nidhi
What is ATP means or stand for.
Benard Reply
is like money for enzime/protein break down or make some molecule, do something.
muayad
Thank x Muayad Ay
Benard
Thank x Muayad Ay
Benard
It stands for ADENOSINE TRIPHOSPHATE
AAGifty
state why the milk is kept at an optimum temperature
Philile Reply
Too prevent it from going bad since it's very watery and very notorious making it easy to go bad
Mukama
is the law of independent assortment same as the law of dominance?
Danny Reply
explain the process of digestion in animal
Lephetha Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Biology' conversation and receive update notifications?

Ask