Nematode trapping fungi: Difference between revisions

From MicrobeWiki, the student-edited microbiology resource
Line 78: Line 78:
Enter summaries of recent research here--at least three required
Enter summaries of recent research here--at least three required
<br>
<br>
==="[http://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_5/pt5/nemato/31626.pdf The nematophagous fungus Verticilium chlamydosporizkrn as a potential biological control agent for Meloidogyne arenaria]"===


==References==
==References==

Revision as of 09:09, 8 April 2013

This student page has not been curated.

Introduction

Electron micrograph of a nematode being trapped by fungal rings.


Nematode trapping fungi, or “nematophageous fungi,” are carnivorous fungi that have developed methods and structures that enable them to successfully trap and consume nematodes. Nematode trapping fungi are responsible for keeping the nematode population in check and are an important part of the subsoil ecosystem. These fungi prey on nematodes and are in turn consumed by organisms on the next trophic level. Nematophageous fungi use several methods to hunt their prey. These methods include living within the nematode and slowly consuming them as well as spreading diseases through nematode populations. The fungi also live in the soil and set traps for the nematodes to squirm into.

Biological interaction

Nematophagous fungi and nematodes share a special predator-prey relationship. The nematodes, like many other soil inhabitants, secrete chemicals as they travel through the soil. Fungi that prey upon these nematodes have found a way to detect and respond to the existence of these chemicals.The fungi have also developed many sophisticated ways to trap the nematodes by attacking from both outside and within the nematode.

Detecting the Nematodes


In order to effectively hunt its prey, many species of fungi have developed the ability to detect some of the chemicals that nematodes use to communicate and grow. These chemicals are detected when the nematodes wander too close to the fungus. And if the fungus is in need of nutrients that are not provided in its diet, it will create traps in the area in which it detected the chemicals and thus effectively hunting its prey.

Secretion by Nematodes


Nematodes produce a highly conserved family of small molecules called ascarosides.These small molecules are special to the nematodes and the fungi are able to detect them. Different species of nematode produce different varieties of ascarosides.

Detection by Fungi


Traps to ensnare the nematode are created when these ascarosides are detected.

Trapping the Nematodes


Fungi use many methods in order to ensnare their prey. These fungi can strike from the outside as well as from the inside.

Hyphal Rings

Electron micrograph of the constriction of a hyphal loop and a nematode being trapped by such a loop.

One method used by fungi to trap nematodes is the fungal ring. The fungus produces hyphae that end in an open constricting loop. When a nematode swims through this loop, the loop suddenly fills with water. This sudden change in the physiology of the loop causes the diameter of the inside of the loop to narrow and in turn constricts around the nematode. Within 24 hours, hyphae form from within the loop and penetrate the nematode as it begins to digest it.

Adhesive Hyphae

Electron micrograph of a network of adhesive hyphae.

Another method commonly used by nematophagous fungi is the use of adhesive hyphae. The fungi who utilize this method create adhesive knobs or nets out of adhesive hyphae. The fungus creates such structures in order to trap the nematode within the structure, and by utilizing the adhesive hyphae the nematode becomes easily ensnared thus providing the fungus with a nitrogen rich meal.

Nematotoxic Compounds

Nematode trapping fungi can use either or both of the methods listed above in order to trap their prey. But some fungi such as the Pleurotaceae family of mushrooms also take it a step further. This family of fungi utilize adhesive knobs to catch nematodes, but once the nematode is caught the fungus secretes a nematacide that kills the nematode and prevents its escape. This extra step is not used by all nematode trapping fungi, but it is utilized by some. It is an extra step of insurance that guarantees that those nematodes that are caught are unable to escape.

Attacking from Within

While many kinds of fungi use traps to catch nematodes, there are also others that live within the nematode and cause damage from there.

Endoparasitic Fungi

Fungi that live within the nematode can infect the nematode at any stage depending on the species of fungus. The infection can be done perorally as in through the mouth or percutanously which means through the skin. From within the nematode, the fungus can consume nutrients meant for the nematode's growth and spread to other nematodes when able. These endoparasitic fungi can spread throughout a community in a measurably short time and spread diseases throughout the process.

Niche

Describe the physical, chemical, or spatial characteristics of the niche where we might find this interaction, using as many sections/subsections as you require. Look at other topics available in MicrobeWiki. Create links where relevant.

Due to the overwhelming abundance of nematodes throughout the world it is easier to say where nematodes cannot be found than to list the many places that they can be found. This being said, the interaction between fungus and nematode is limited to environments where they can both thrive.

Nematode Habitats

Nematodes survive and thrive in almost every habitat on earth. They are present on both land and in aquatic environments. The only stipulation that can limit the spread of nematodes is availability of moisture and prey.

Aquatic Habitats

Nematodes can be found in great abundance in both fresh and sea water. Nematodes can infect aquatic plants and animals.

Terrestrial Habitats

Nematodes can be found in nearly soil on earth. As long as a minimal amount of soil moisture and some sort of organism is present in the soil, it is certain that nematodes can be found there.

Fungal Habitats

Fungi can be found in almost every soil and water source in the world. Although not as enormously widespread and survivable as nematodes, fungi are nearly ever present. Fungi are important to the breakdown of organic compounds and require organic compounds, moisture, and proper pH to survive.

Aquatic Habitats

Fungi can be easily found in both fresh and saltwater sources.

Terrestrial Habitats

Soil is the most common environment for fungi. It is present in some extent in nearly every soil and does the work of breaking down organic materials.

Microbial processes

What microbial processes are important for this microbial interaction? Does this microbial interaction have some ecosystem-level effects? Does this interaction affect the environment in any way? Describe critical microbial processes or activities that are important in this interaction, adding sections/subsections as needed. Look at other topics in MicrobeWiki. Are some of these processes already described? Create links where relevant.

Subsection 1

Subsection 1a

Subsection 1b

Subsection 2


Key Microorganisms

There are many different varieties of nematophagous fungi. And many have yet to be studied extensively. They are present nearly everywhere in the world and have evolved to hunt nematodes in their own way. These nematophagous fungi have evolved alongside the nematodes that they consume and have over time developed methods that are most useful to catch the nematode species that they hunt the most.


Varieties of Nematode Trapping Fungi

Fungal Ring Users

Notable fungi that use a fungal ring include Drechslerella anchonia, Drechslerella dactyloides, and Drechslerella brochopaga.

Adhesive Hyphae Users

Fungi that utilize adhesive hyphae include Dactylellina candida, Drechmeria coniospora, and Arthrobotrys oligospora.

Nematotoxin Users

Notable nematotoxin users include Coprinus comatus, Stropharia rugosoannulata, Arthrobotrys dactyloides, and the Pleurotaceae family.

Endoparasitic Fungi

Fungi that survive as spores in the soil until the time is right include Drechmeria coniospora, Pythium caudatum, and Harposporium leptospira.

Current Research

Due to the over abundance of nematodes and the huge economic loss that is caused by them each year, many experiments are under way in order to find a way to alleviate this damage and promote plant health.

Enter summaries of recent research here--at least three required

"The nematophagous fungus Verticilium chlamydosporizkrn as a potential biological control agent for Meloidogyne arenaria"

References

Loynachan, T. 2007.

Edited by Brad Launer, a student of Angela Kent at the University of Illinois at Urbana-Champaign.