''Trichoderma koningii'' is a very common soil dwelling
saprotroph
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 (f ...
with a worldwide distribution.
It has been heavily exploited for agricultural use as an effective
biopesticide
A Biopesticide is a biological substance or organism that damages, kills, or repels organisms seens as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships.
They are obtained from organisms inclu ...
, having been frequently cited as an alternative biological control agent in the regulation of fungi-induced plant diseases.
They are
endosymbiont
An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship.
(The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within" ...
s associated with plant root tissues, exhibiting
mycoparasitism
A mycoparasite is an organism with the ability to parasitize fungi.
Mycoparasites might be biotrophic or necrotrophic, depending on the type of interaction with their host.
Types of mycoparasitic organisms
Myco-heterotrophy
Various plants may ...
and promoting plant growth due to their capacity to produce different
secondary metabolite
Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norm ...
s.
''Trichoderma koningii'' is a species belonging to the genus ''
Trichoderma
''Trichoderma'' is a genus of fungi in the family Hypocreaceae that is present in all soils, where they are the most prevalent culturable fungi. Many species in this genus can be characterized as opportunistic avirulent plant symbionts. This ref ...
''. Fungi in this genus are able to adapt to different
ecological niche
In ecology, a niche is the match of a species to a specific environmental condition.
Three variants of ecological niche are described by
It describes how an organism or population responds to the distribution of resources and competitors (for ...
s and can colonize their habitats effectively, allowing them to be powerful
antagonist
An antagonist is a character in a story who is presented as the chief foe of the protagonist.
Etymology
The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, riv ...
s and biocontrol agents.
Typical of ''Trichoderma'' species is having a fast growth rate and the production of green or
hyaline
A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none.
Histopathology
Hyaline cartilage is ...
conidia
A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to the ...
on a branched
conidiophore
A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an Asexual reproduction, asexual, non-motility, motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are al ...
structure.
History and taxonomy
''Trichoderma koningii'' was first described by the Dutch mycologist
Oudemans in 1902 as one of the species in the microbial flora he obtained from a nature preserve in The
Netherlands
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, established_title = Before independence
, established_date = Spanish Netherl ...
.
After the genus was erected in 1794, there was difficulty in distinguishing and identifying the different species apart due to their very similar morphological characteristics. It wasn't until 1969 that a concept of classification was proposed by Rifai to reduce confusion on the taxonomy of ''Trichoderma''.
He recognized ''T. koningii'' as one of the nine "aggregates" or groups of species in the genus. This aggregate consists of 12 species within three lineages that have similar morphology as the "true" ''T. koningii'' but can be differentiated from each other by their phenotypic characters and geographic distributions.
In 1991, Bissett divided the genus into five sections to classify the species on the basis of the branching of conidiophores. He included ''T. koningii'' in ''Trichoderma'' sect. ''Trichoderma''.
In 2004, Chaverri and Samuels proposed another taxonomic classification based on molecular phylogenetic analysis. ''T. koningii'' and its aggregates were included in the ''T. viride'' clade.
Growth and morphology
The conidiophores of ''T. koningii'' are branched and organized in a pyramidal structure with longer branches at the base that progressively shortens as it nears the tip. Primary and secondary branches arise in a right-angle degree and are often symmetrical on either side of the node along the main axis.
Phialide
The phialide ( ; el, phialis, diminutive of phiale, a broad, flat vessel) is a flask-shaped projection from the vesicle (dilated part of the top of conidiophore) of certain fungi. It projects from the mycelium without increasing in length unless ...
s are usually in 3–4 whorls that arise from the tip of the main branch and from lateral branches at intercalary positions on the conidiophore.
Some phialides on widely-spaced branches are flask-shaped, resembling a wine bottle, whereas some tend to have a very swollen middle when in dense clusters or "pseudo-
whorls
A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs).
Whorls in nature
File:Photograph and axial plane floral d ...
".
''T. koningii'' typically produces smooth and
ellipsoidal
An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation.
An ellipsoid is a quadric surface; that is, a surface that may be defined as the z ...
(egg-shaped) conidia, with a mean length of 4.1–4.3 µm, that aggregates in a slimy green mass at the tip of the phialides. The
chlamydospores
A chlamydospore is the thick-walled large resting spore of several kinds of fungi, including Ascomycota such as '' Candida'', Basidiomycota such as ''Panus'', and various Mortierellales species. It is the life-stage which survives in unfavourable c ...
are pale brown, globe-like in shape, and are located at terminal and intercalary positions on the hyphae.
In culture, colonies display rapid growth on
potato dextrose agar
Potato dextrose agar (BAM Media M127
from the U.S. (PDA), as cream-coloured in the beginning but later turns green because of sporulation.mycelium
Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrate (biology), substrates. A typical single ...
with a radius of 50–60 mm. During conidial production, colouration first begins at the centre then later spreads outward in dark or dull green concentric rings that are vague to noticeable.teleomorph
In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota:
*Teleomorph: the sexual reproductive stage (morph), typically a fruiting body.
*Anamorph: an ase ...
, ''Hypocrea koningii'', is characterized by cushion-shaped stromata (sing. stroma) that are broadly attached to the surface of a substrate but are free at the margins. The surface of the stroma appears slightly-wrinkled. Mature stromata are brown to brownish-orange, whereas the young ones have a tan color with villi sprouting from the surface. These short hairs are lost during development. Perithecia
An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mo ...
(fruiting bodies) are elliptic
In mathematics, an ellipse is a plane curve surrounding two focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant. It generalizes a circle, which is the special type of ellipse in ...
, 160–280 µm long and 100–185 µm wide. The perithecial neck has a length of 53–90 µm. Asci (sing. ascus
An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...
) within the fruiting bodies are typically cylindrical
A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base.
A cylinder may also be defined as an infini ...
, with dimensions of 60–70 x 4–5.7 µm and thickening at the apex. The ascospores
An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or ...
of ''H. koningii'' are hyaline and fill up the ascus in a single row. They are initially