Intraspecific antagonism
Encyclopedia
Intraspecific antagonism means a disharmonious or antagonistic interaction between two individual
s of the same species
. As such, it could be a sociological
term, but was actually coined by Alan Rayner
and Norman Todd working at Exeter University in the late 1970s, to characterise a particular kind of zone line formed between wood-rotting fungal mycelia
. Intraspecific antagonism is one of the expressions of a phenomenon known as vegetative or somatic incompatibility.
for many reasons, including host reactions against parasitic encroachment, and inter-specific interactions, but the lines observed by Rayner and Todd when transversely-cut sections of brown-rotted Birch
tree trunk or branch were incubated in plastic bags appeared to be due to a reaction between different individuals of the same species of fungus
.
This was a startling inference at a time when the prevailing orthodoxy within the mycological
community was that of the "Unit Mycelium". This was the theory that when two different individuals of the same species of basidiomycete wood rotting fungi grew and met within the substratum, they fused, cooperated, and shared nuclei freely. Rayner and Todd's insight was that basidiomycete fungi individuals do, in most "adult" or dikaryotic
cases anyway, retain their individuality.
A small stable of postgraduate and postdoctoral students helped elucidate the mechanisms underlying these inter-mycelial interactions, at Exeter University (Todd) and the University of Bath
(Rayner), over the next few years.
Although the attribution of individual status to the mycelia confined by intraspecific zone lines is a comparatively new idea, zone lines themselves have been known since time immemorial. The term spalting
is applied by woodworkers to wood showing strongly-figured zone lines, particularly those cases where the area of "no-man's land" between two antagonistic conspecific mycelia is colonised by another species of fungus. Dematiaceous
hyphomycetes, with their dark-coloured mycelia, produce particularly attractive black zone lines when they colonise the areas occupied by two antagonistic basidiomycete individuals. Spalted wood can be difficult to work, since different individual wood-rotting fungi have different decay efficiencies, and thus produce zones of different softness, and the zone lines themselves are usually unrotted and hard.
Instraspecific antagonism can also sometimes be of assistance in quickly recognising the membership of clones in those fungi, particularly root-rots such as Armillarea
where individual mycelia may colonise large areas, or more than one tree.
It is even the subject of a recent patent http://www.freepatentsonline.com/4698305.html.
Individual
An individual is a person or any specific object or thing in a collection. Individuality is the state or quality of being an individual; a person separate from other persons and possessing his or her own needs, goals, and desires. Being self expressive...
s of the same species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. As such, it could be a sociological
Sociology
Sociology is the study of society. It is a social science—a term with which it is sometimes synonymous—which uses various methods of empirical investigation and critical analysis to develop a body of knowledge about human social activity...
term, but was actually coined by Alan Rayner
Alan Rayner
Alan Rayner is a British biologist and educator.-Career:Rayner obtained BA and PhD degrees in Natural Sciences at King's College, Cambridge, and was a reader in biology at the University of Bath from 1985 to 2011...
and Norman Todd working at Exeter University in the late 1970s, to characterise a particular kind of zone line formed between wood-rotting fungal mycelia
Mycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
. Intraspecific antagonism is one of the expressions of a phenomenon known as vegetative or somatic incompatibility.
Fungal individualism
Zone lines form in woodWood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
for many reasons, including host reactions against parasitic encroachment, and inter-specific interactions, but the lines observed by Rayner and Todd when transversely-cut sections of brown-rotted Birch
Birch bracket
Piptoporus betulinus, commonly known as the birch polypore, birch bracket, or razor strop, is one of the most common polyporous bracket fungi and, as the name suggests, grows almost exclusively on birch trees. The brackets burst out from the bark of the tree, and these fruiting bodies can last for...
tree trunk or branch were incubated in plastic bags appeared to be due to a reaction between different individuals of the same species of fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
.
This was a startling inference at a time when the prevailing orthodoxy within the mycological
Mycology
Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, medicinals , food and entheogens, as well as their dangers, such as poisoning or...
community was that of the "Unit Mycelium". This was the theory that when two different individuals of the same species of basidiomycete wood rotting fungi grew and met within the substratum, they fused, cooperated, and shared nuclei freely. Rayner and Todd's insight was that basidiomycete fungi individuals do, in most "adult" or dikaryotic
Dikaryon
Dikaryon is from Greek, di meaning 2 and karyon meaning nut, referring to the cell nucleus.The dikaryon is a nuclear feature which is unique to some fungi, in which after plasmogamy the two compatible nuclei of two cells pair off and cohabit without karyogamy within the cells of the hyphae,...
cases anyway, retain their individuality.
A small stable of postgraduate and postdoctoral students helped elucidate the mechanisms underlying these inter-mycelial interactions, at Exeter University (Todd) and the University of Bath
University of Bath
The University of Bath is a campus university located in Bath, United Kingdom. It received its Royal Charter in 1966....
(Rayner), over the next few years.
Applications of intraspecific antagonism
Spalting
Spalting is any form of wood coloration caused by fungi. Although primarily found in dead trees, spalting can also occur under stressed tree conditions or even in living trees...
is applied by woodworkers to wood showing strongly-figured zone lines, particularly those cases where the area of "no-man's land" between two antagonistic conspecific mycelia is colonised by another species of fungus. Dematiaceous
Dematiaceous
Dematiaceous is a term to denote dark-colored. It is generally used to refer to a group of fungi, the Dematiaceous molds, that produce melanin in their cell walls. The melanin is responsible for the characteristic brown color of the fungal colonies when grown on agar.Dematiaceous fungi show...
hyphomycetes, with their dark-coloured mycelia, produce particularly attractive black zone lines when they colonise the areas occupied by two antagonistic basidiomycete individuals. Spalted wood can be difficult to work, since different individual wood-rotting fungi have different decay efficiencies, and thus produce zones of different softness, and the zone lines themselves are usually unrotted and hard.
Instraspecific antagonism can also sometimes be of assistance in quickly recognising the membership of clones in those fungi, particularly root-rots such as Armillarea
Honey fungus
Honey fungus, or Armillaria or оpenky , is a genus of parasitic fungi that live on trees and woody shrubs. It includes about 10 species formerly lumped together as A. mellea. Armillarias are long lived and form some of the largest living organisms in the world...
where individual mycelia may colonise large areas, or more than one tree.
It is even the subject of a recent patent http://www.freepatentsonline.com/4698305.html.