Trichoderma is a genus of fungi 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 refers to the ability of several Trichoderma species to form mutualistic endophytic relationships with several plant species. The genomes of several Trichoderma species have been sequenced and are publicly available from the JGI.
Scientific classification
Kingdom:Fungi
Division:Ascomycota
Subdivision:Pezizomycotina
Class:Sordariomycetes
Order:Hypocreales
Family:Hypocreaceae
Trichoderma species include:
(89 accepted species)
T. aggressivum T. amazonicum T.
asperellum
T. atroviride T.
aureoviride T. austrokoningii
T. brevicompactum T. candidum T.
catoptron
T. caribbaeum var. caribbaeum T. viridescens
T. caribbaeum var. aequatoriale
T. caribbaeum var. aequatoriale
T. cremeum T.
ceramicum T. cerinum
T. chlorosporum T.
chromospermum T. cinnamomeum
T. citrinoviride T.
crassum T.
cremeum
T. dingleyeae T.
dorotheae T. effusum
T. erinaceum T.
estonicum T. fertile
T. gelatinosus T.
ghanense T. hamatum
T. harzianum T. narcissi T. helicum
T. intricatum T.
konilangbra T. koningii
T. koningiopsis T.
longibrachiatum T. longipile
T. minutisporum T.
oblongisporum T.
ovalisporum
T. petersenii T.
phyllostahydis T.
piluliferum
T. pleuroticola T.
pleurotum T. polysporum
T.
pseudokoningii T.
pubescens T. reesei
T. rogersonii T. rossicum T. saturnisporum
T. sinensis T.
sinuosum T. songyi
T. sp. MA 3642 T.
sp. PPRI 3559 T.
spirale
T. stramineum T.
strigosum T. stromaticum
T. surrotundum T.
taiwanense T. thailandicum
T.
thelephoricolum T. theobromicola T.
tomentosum
T. velutinum T.
virens T.
virgatum Occurence
Trichoderma species are frequently isolated from forest or agricultural soils at
all latitudes. Hypocrea species are most frequently found on bark or on
decorticated wood but many species grow on bracket fungi (e.g. H. pulvinata),
Exidia (H. sulphurea) or bird's nest fungi (H. latizonata) or agarics (H.
avellanea).
Trichoderma
colonizes on the root structure of a host plant, attacking and killing
soil-borne pathogens before they can harm the plant. Then the trichoderma
multiplies and thrives as the host plant grows, providing season-long
protection while sending messages through biochemical pathways to improve plant
performance and yield.
Several strains of Trichoderma have been developed as biocontrol agents against fungal diseases of plants. The various mechanisms include antibiosis, parasitism, inducing host-plant resistance, and competition. Most biocontrol agents are from the species T. harzianum, T. viride and T. hamatum. The biocontrol agent generally grows in its natural habitat on the root surface, and so affects root disease in particular, but can also be effective against foliar diseases.
They are widely distributed and have a variety of biological activities. Some species, such as T. harzianum form the basis for commercial products applied for biological control of plant pathogenic fungi. Some Trichoderma species have beneficial effects on plant growth and development. And some species, such as T. reesei have important industrial applications as producer of cellulolytic and hemicellulolytic enzymes. Trichoderma strains in agricultural soils are likely to be more effective biocontrol agents, since they are already adapted to variable field conditions.
Trichoderma colonizes root surfaces upon contact to increase the soil’s microbial activity and stimulate the root system for more efficient water and nutrient absorption. Biologicals are a natural way to improve agricultural production and plant yields. Some of the most notable benefits of trichoderma are that it:
Enhances anti-oxidative potential of the host plant;
Triggers systematic disease resistance mechanisms in plants;
Enhances the uptake of water and nutrients, especially nitrogen, which leads to higher nutrient metabolism;
Increases photosynthesis of the host plant, which leads to a healthier plant.
Results of Trichoderma
Here
are some consistent results of trichoderma treatment:
1. Increased yield in all crops
2. Greater resistance to plant stresses such as disease, drought, and
salt.
3. Deeper root systems, greater root mass, stronger stalks, and increased
tillering.
4. Better water use efficiency
5. Reduced need for the use of fertilizer, resulting in lower production
costs for growers.
6. When the host plant dies, the trichoderma dies, with little if any
build-up in the soil.
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| Right Root- With Trichoderma |
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| Left Root- With Trichoderma |
Trichoderma as a Causal
Agent of Disease-Harmful Nature
T. aggressivum (formerly T. harzianum biotype 4) is the causal agent of green mold, a
disease of cultivated button mushrooms. Trichoderma viride is the causal agent
of green mold rot of onion. A strain of Trichoderma viride is a known cause of
dieback of Pinus nigra seedlings.
Trichoderma spp is the cause of the green mold disease in mushroom cultivation
production. Many disinfection treatments are commonly applied to lignocellulose
substrates to prevent contamination. Mushroom growers are usually worried about
the contaminations that may occur after these treatments during handling or
spawning.
Trichoderma sp, also known as green mold, is a cellulolytic filamentous fungus, which
frequently contaminates mushroom substrates. This fungus is often observed in
the early stages of the process, especially during spawning run period, but
also during cropping period and causes huge losses in mushrooms crops. Green mold causes economic
losses not only in Agaricus but also in Pleurotus and Lentinula cultivation.
Various
treatments are used for the preparation of substrate for mushroom cultivation
to eliminate competitive fungi. They are: steam sterilization, steam
pasteurization, hot water immersion and chemical treatment, but they are not
always successful. Contaminations according to mushroom growers may even occur
sporadically after these treatments during handling or spawning.
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| Green Mold in Mushroom |
The main antagonist used in disease control in
Agriculture is the fungus Trichoderma harzianum, a low cost
biocontrol agent that can establish itself in different pathosystems, has
moderate effects on soil balance and does not harm benefitial organims that
contribute towards pathogen’s control. This biocontrol agent has not harmful
effects on humans, wild life and other beneficial organisms. T. harzianum is a
safe and effective biocontrol agent in both natural and controlled environments
that does not accumulate in the food chain and to which it has not been described
resistance. Trichoderma strains used as biocontrol agents can act:
a) colonizing the soil and/or
parts of the plant, occupying a physical space and avoiding the multiplication
of the pathogens;
b) producing cell wall degrading enzymes
against the pathogens;
d) promoting the plant
development and
e) inducing the defensive
mechanisms of the plant.