A mycoparasite is an organism with the ability to parasitize

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

. Mycoparasites might be biotrophic or necrotrophic, depending on the type of interaction with their host.

Types of mycoparasitic organisms

Myco-heterotrophy

Various

plants Plants are the eukaryotes that form the kingdom Plantae; they are predominantly photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars f ...

may be considered mycoparasites, in that they parasitize and acquire most of their nutrition from fungi during a part or all of their life cycle. These include many

orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan plants that are found in almost every habitat on Eart ...

seedlings, as well as some plants that lack chlorophyll such as '' Monotropa uniflora''. Mycoparasitic plants are more precisely described as myco-heterotrophs.

Mycoparasitic bacteria

Some

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

live on or within fungal cells as parasites or symbionts.

Mycoparasitic viruses

Some

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almo ...

, called mycoviruses live on or within fungal cells as parasites or symbionts.

Mycoparasitic fungi

Many mycoparasites are

, though not all fungicolous fungi are

parasites Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

(some are commensals or saprobes.) Biotrophic mycoparasites acquire nutrients from living host cells. Necrotrophic mycoparasites rely on dead host cells, which they might first kill with toxins or enzymes (

saprophytic Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ...

growth).

Kinds of mycoparasitic interactions

Biotrophic and necrotrophic mycoparasites

Biotrophic mycoparasites get nutrients from living host cells and growth of these parasites is greatly influenced by the metabolism of the host. Biotrophic mycoparasites tend to show high host specificity, and often form specialized infection structures. Necrotrophic mycoparasites can be aggressively antagonistic, invading the host fungus and killing, then digesting components of its cells. Necrotrophic parasites tend to have low host specificity, and are relatively unspecialized in their mechanism of parasitism.

Balanced and destructive mycoparasites

Balanced mycoparasites have little or no destructive effect on the host, whereas destructive mycoparasites have the opposite effect. Biotrophic mycoparasites are generally considered to be balanced mycoparasites; necrotrophic mycoparasites use toxins or

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

s to kill host cells, therefore necrotrophic mycoparasites are usually considered to be destructive mycoparasites. However, in some combinations, the parasite may live during its early development as a biotroph, then kill its host and act more like destructive mycoparasites in late stages of parasitization.

Mechanisms of Mycoparasitism

The four main steps of mycoparasitism include target location; recognition; contact and penetration; and nutrient acquisition.

Target location

Many research indicate that

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

l growth direction,

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

germination, and bud tube elongation of mycoparasitic fungi may exhibit

tropism In biology, a tropism is a phenomenon indicating the growth or turning movement of an organism, usually a plant, in response to an environmental stimulus (physiology), stimulus. In tropisms, this response is dependent on the direction of the s ...

in response to detection of a potential host. This tropic recognition reaction is thought to arise from detection of signature chemicals of the host; the direction of the concentration gradient determines the growth direction of the parasite. As the mycoparasitic interaction is host-specific and not merely a contact response, it is likely that signals from the host fungus are recognized by mycoparasites such as '' Trichoderma'' and provoke transcription of mycoparasitism-related genes.

Recognition

When mycoparasites contact their fungal host, they will recognize each other. This recognition between mycoparasites and their host fungi may be related to the

agglutinin An agglutinin is a substance in the blood that causes particles to coagulate and aggregate; that is, to change from fluid-like state to a thickened-mass (solid) state. Agglutinins can be antibodies that cause antigens to aggregate by binding t ...

on the cell surface of the mycohost. Carbohydrate residues on the cell wall of mycoparasites might bind to

lectin Lectins are carbohydrate-binding proteins that are highly specific for sugar Moiety (chemistry), groups that are part of other molecules, so cause agglutination (biology), agglutination of particular cells or precipitation of glycoconjugates an ...

s on the surface of the host fungi to achieve mutual recognition.

Contact and penetration

Once a mycoparasitic fungus and its host recognize each other, both may exhibit changes in external form and internal structure. Different mycoparasitic fungi form different structures when interacting with their hosts. For example, the

e of some mycoparasitic fungi form specialized contact cells resembling haustoria on the hyphae of their hosts; others may coil around the hyphae of their host fungus or penetrate then grow inside host hyphae. Nectrophic mycoparasites may kill host hyphae with toxins or enzymes before invading them.

Application

Mycoparasitic fungi can be important controls of plant disease fungi in natural systems and in agriculture, and may play a role in

integrated pest management Integrated pest management (IPM), also known as integrated pest control (IPC) integrates both chemical and non-chemical practices for economic control of pests. The UN's Food and Agriculture Organization defines IPM as "the careful consideratio ...

(IPM) as biological controls Some '' Trichoderma'' species have been developed as biocontrols of a range of commercially important diseases, and have been applied in the

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Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

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, and other countries to control plant diseases caused by '' Rhizoctonia solani'', ''

Botrytis cinerea ''Botrytis cinerea'' is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" ...

'', '' Sclerotium rolfsii'', '' Sclerotinia sclerotiorum'', '' Pythium'' spp., and ''

Fusarium ''Fusarium'' (; ) is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the s ...

'' spp. as a promising alternative to chemical pesticides. Further study of mycoparasitism may drive discovery off more bioactive compounds including biopesticides and biofertilizers. {, class="wikitable" , +List of fungal bioagents with their trade and manufacturers name !Commercial products !Bioagents used !Name of the manufacturer , - , AQ10 biofungicide , '' Ampelomyces quisqualis'' isolate M-10 , Ecogen, Inc. Israel , - , Anti-Fungus , '' Trichoderma'' spp. , Grondortsmettingen De Cuester, Belgium , - , Biofungus , ''Trichoderma'' spp. , Grondortsmettingen De Cuester n. V.Belgium , - , Bas-derma , '' Trichoderma viride'' , Basarass Biocontrol Res. Lab., India , - , Binab T , '' Trichoderma harzianum'' (ATCC 20476) and '' Trichoderma polysporum'' (ATCC 20475) , Bio-Innovation AB, UK , - , Bioderma , ''Trichoderma viride/T. harzianum'' , Biotech International Ltd., India , - , Biofox C , '' Fusarium oxysporum'' (Non- pathogenic) , S. I. A. P. A., Italy , - , Prestop, Prirnastop , '' Gliocladium catenulatum'' , Kemira Agro. Oy, Finland , - , Root Pro, Root Prota to Soilgard , ''Trichoderma harzianum/ Gliocladium virens'' strain GL-21 , Efal Agr, Israel Thermo Trilogy, USA , - , Root shield, Plant shield, T-22 Planter box , ''Trichoderma harzianum'' Rifai strain KRL-AG (T-22) , Bioworks Inc., USA , - , Supresivit , ''Trichoderma harzianum'' , Borregaard and Reitzel, Czech Republic , - , T-22 G, T-22 HB , ''Trichoderma harzianum'' strain KRL-AG2 , THT Inc., USA , - , Trichodex, Trichopel , ''Trichoderma harzianum'' , Makhteshim Chemical Works Ltd., USA , - , Trichopel, Trichoject, Trichodowels, Trichoseal , ''Trichoderma harzianum'' and ''Trichoderma viride'' , Agrimm Technologies Ltd., New Zealand , - , Trichopel , ''Trichoderma harzianum''and ''Trichoderma viride'' , Agrimm Technologies Ltd., New Zealand , - , Trichoderma 2000 , ''Trichoderma'' sp. , Myocontrol Ltd., Israel , - , Tri-control , ''Trichoderma'' spp. , Jeypee Biotechs, India , - , Trieco , ''Trichoderma viride'' , Ecosense Labs Pvt. Ltd., Mumbai, India , - , TY , ''Trichoderma'' sp. , Mycocontrol, Israel

References

Parasites of fungi