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Macrofungi
Macrofungi
Morphology
Taxonomy
Microhabitat
Diversity, abundance and biomass
Macrofungi are the group of fungi which form visible, often
coloured, cup- or cap-like strucures (scientifically known as
“fruiting bodies” or "sporophores") that emerge from the soil.
These fruiting bodies are where the spores are formed. The
spores are small (1-100 µm), usually single-celled, reproductive
structures able to tolerate unfavorable growing conditions (i.e.
drought). Below the fruiting bodies each fungus has a mass of
hyphae, the typical branching thread-like filaments produced
by most fungi. The mycelium is made up of the mass of these
hyphae and is the part of the fungus responsible for its growth. In
the case of soil macrofungi, the largest portion of the mycelium
is hidden since it grows below-ground. When environmental
conditions become favorable, the fungus develops a fruiting body
and spores that, once released, disperse through the air, or are
dispersed by insects or by water.
Macrofungi, taxonomically belonging to the subkigdom Dikarya, are
classified into two main groups: Ascomycota and Basidiomycota.
The Ascomycota, the largest group of macrofungi with more than
60,000 described species, are usually characterized by a cup-like,
or disc-like fruiting body (technically known as ascoma) where
spores are formed within a typical structure, named the “ascus”.
The Basidiomycota (more than 30,000 described species) mostly
have a fruiting body (callebasidioma) with an umbrella-shaped
cap (known as pileus) borne on a stalk (known as stipe) where the
spores are produced.
Macrofungi are found in most habitats, but they are probably
at their most diverse in forests. They need the right climatic
conditions to form fruiting bodies, in particular all of them
need moisture to allow their spores to develop. They can be
saprotrophic, parasitic or mycorrhizal. The saprotrophic species
play a key role in the degradation of decaying organic matter
(soil, leaf litter and dead wood). The parasitic fungi (that get
their nutrition from other living organisms, without providing
any recompense) are responsible for several diseases in plants,
animals (mostly invertebrates) and other fungi. The mycorrhizal
fungi form symbioses with plant roots, a mutualistic association
that is beneficial to both partners.
Fungi are extremely abundant. From 1.5 to 5 million of species
have been estimated but only about 150,000 have been described.
Macrofungi have about 90,000 known species. Together with
bacteria, fungal hyphae constitute the largest portion of the
microbial biomass of soil. Generally, fungal biomass is found to
be greater than bacterial biomass in forest soils.
How a fungus is made
The fungal hyphae that usually grow in soil have a branching
structure that remind of plant roots and allow the fungus to get
nutrients from soil.
i
A hypha is a long, branching filamentous structure of a fungus. In
most fungi, hyphae are the main mode of growth, and collectively
form the mycelium.
ii Hyphae grow at their tips. Hyphae can branch through the
bifurcation of a growing tip, or by the emergence of a new tip from
an established hypha.
iii There are different types of hyphae:
-- septate: they have cross walls (called septa) at fairly regular
intervals;
-- aseptate or coenocytic: they do not have septa.
iv Hyphae can fuse one to another by tip-to-tip contact. This process
is known as anastomosis.
v Yeasts are fungi that do not have hyphal structure since they are
the only unicellular fungi.
Ascomycoyta is a group of fungi that usually have a visible part, scientifically defined as the fruting body, with a cup-like shape. (a)
Aleuria aurantia (SA); (b) Rhodoscypha ovilla (AV); (c) Phillipsia subpurpurea (SA); (d) Lachnum virginium (SA).
Fungi: edible, poisonous, bioluminescent and giant
i
There are several edible Basidiomycota and Ascomycota. Mushrooms, such as Boletus
edulis and truffles (Tuber species), are eaten in many countries.
ii Some Basidiomycota produce deadly toxins, such as the amatoxin produced by
Amanita phalloides. 30 grammes of this fungus may kill a person; others, such as
Ganoderma lucidum, are considered medicinal fungi.
iii Some Basidiomycota (e.g., species belonging to genus Mycena) are bioluminescent.
iv In Hainan Island (southern China) a giant specimen of Fomitiporia ellipsoidea
(belonging to the so called bracket fungi, Basidiomycota) was found. It was 20 years
old, and its estimated volume was 409,000-525,000 cm3 and weight was 400–500
kg. This represents the largest fungal fruiting body (both in volume and in weight)
ever found.
Basidiomycota is a group of fungi that comprises the familiar mushrooms.
Their visible part commonly has an umbrella-like shape. (a) Hygrocybe sp.
(SA); (b) Boletus luridiformis (AV); Gymnopilus purpuratus (SA).
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Global Soil Biodiversity Atlas | CHAPTER II - SOIL ORGANISMS
Mycena chlorophos is a bioluminescent fungus that can be
foun in Asia (e.g., Japan and Sri Lanka), Oceania (Australia)
and South America (Brazil). The mechanism underlying the
bioluminescent has not been fully described yet. (SA)
Fungi are very diverse in terms of both shape and color. Some fungal species showing these aspects: (a) Leratiomyces sp.; (b) Plectania campylospora; (c)
Hygrocybe graminicolor; (d) Scutellinia scutellata; (e) Cortinarius archeri; (f) Cyathus striatus; (g) Cyptotrama aspratum; (h) Gastreum triplex. (SA)
Spores allow the fungi to be reproduced. Thanks to their microscopic
dimension, they can easily disperse through air or water. They grow into
new individuals under suitable conditions of moisture, temperature,
and food availability. (a) Spores of Ascomycota -blu colored- develop
inside structures named asci (LP); (b) Electron micrograph of spores
from the puffball Calbovista subsculpta (SJ); (c) Electron micrograph of
spores from Austroboletus mutabilis (RH); (d) Spores of Basidiomycota
develop inside strucures (red colored) named basidia (LP); (e) Spores of
Entoloma sp. (LK); (f) Spores of Botryobasidium aureum (JP).
CHAPTER II - SOIL ORGANISMS | Global Soil Biodiversity Atlas
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