So let's focus mainly on one fungi species in particular and two varieties, Trichoderma virens and Trichoderma harzianum
|Image: US Department of Agriculture|
|Image: Manidharma Biotech|
Plant root colonization by different Trichoderma strains can activate in the plant a systemic defense response that is effective against a very wide range of plant pathogens. A plant's immune system also has a wide variety hormones which play pivotal roles in the regulation of the defense signaling network that leads to the processes of systemic resistance triggered by beneficial micro-organisms. One of the most important of these chemical defenses, jasmonic acid and ethylene (like ethylene gas for fruit ripening) signaling pathways are generally essential for triggering these immune system responses. However, this Trichoderma Immune System Response (TISR) is believed to involve a wider variety of signaling routes, interconnected in a complex network of cross-communicating hormone pathways. For example the experiment above with tomatoes grown in Greenhouses is a perfect example of where Trichoderma harzianum can trigger an immune response against a leaf pathogen called Botrytis cinerea. Root colonization by the Trichoderma harzianum provided these tomato leaves with much more resistant to Botryis cinerea independently of major effects on plant nutrition. You can see the results from the above images which show tomatoes grown under greenhouse conditions which displayed vigorous health compared to the one which succumbed to the infection. Now I've never personally experience such infection on any tomato leaves in gardens I've raised, but this type of fungus disease is much more common in a more humid greenhouse environment than outdoors. However this disease is more common among grapes and strawberries. However, once again it's the closed in humid greenhouse environment which makes this a challenge and this is important because these days so much of our vegetables in and around urban areas where land is scare are produced. So how kool is this that the Trichoderma fungi can create the necessary hormonal signalling network behind the systemic resistance induced by Trichoderma harzianum in tomato instead of farmers having to rely on the traditional cocktails of chemical fungicides ?
|Model: Department of Microbiology and Symbiotic Systems, Granada Spain|
|Photo courtesy of: Charles M. Kenerley and Prasun Mukherjee.|
"Coiling of Trichoderma hyphae around Rhizoctonia (a basidiomycete pathogen). The coiling response of T. virens is induced by the presence of host hyphae and precedes penetration of the host."
|Photo Courtesy of Dr Randy Martin, Bioworks, Inc.|
"Scanning electron micrograph of the surface of a hyphae of the plant pathogen Rhizoctonia solani after mycoparasitic Trichoderma hyphae invades the pathogen by boring holes into the pathogen with various cell wall degrading enzymes"
"Trichoderma species are free-living fungi that are common in soil and root ecosystems. They have been widely studied for their capacity to produce antibiotics, parasitize other fungi, and compete with deleterious plant microorganisms. Until recently, these traits were considered to be the basis for how Trichoderma exert beneficial effects on plant growth and development. However, it is becoming increasingly clear that certain strains also have substantial direct influence on plant development and crop productivity. Trichoderma enhancement of plant growth has been known for many years and can occur in axenic systems or in soils"
"In maize (Corn) plants, Trichoderma inoculation affected root system architecture, which was related to increased yield of plants. Reported effects include enhanced root biomass production and increased root hair development. The root system is important for plant fitness because it provides anchorage, contributes to water use efficiency, and facilitates the acquisition of mineral nutrients from the soil. Many lines of evidence strongly support a role for auxin in the regulation of root system architecture. Application of natural and synthetic auxins increases lateral root and root hair development, whereas auxin transport inhibitors reduce root branching."
"Conversely, increased formation of lateral roots has been observed in Arabidopsis thaliana (or Thale Cress) mutants with elevated auxin content . . "
" . . .Despite auxin being a major player in root growth regulation, little is known about its role in plant growth promotion by fungi."
"To elucidate the signaling mechanisms by which Trichoderma species promote plant growth and development, we evaluated the Arabidopsis response to inoculation with two Trichoderma species, Trichoderma atroviride (formerly known as Trichoderma harzianum) and Trichoderma virens. The two fungal species were found to promote Arabidopsis seedling growth under axenic conditions. Plant growth promotion elicited by these fungi correlated with prolific formation of lateral roots. A role for auxin signaling in mediating the observed developmental alterations by Trichoderma virens inoculation in plants was inferred from tests using the auxin-responsive marker constructs. We further show that Trichoderma virens is able to produce the indolic compounds indole-3-acetic acid (IAA), indole-3-acetaldehyde (IAAld), and indole-3-ethanol (IEt), which may play roles in mediating plant growth promotion by this fungus."
Important terms to define and explain from the above research article:
"Auxins" - a plant hormone that causes the elongation of cells in shoots and is involved in regulating plant growth. Basically can encourage growth by means of a signaling process as seen in the examples of thick Corn root infrastructure.
"Jasmonic Acid" (JA) - and its derivatives are lipid-based hormone signals that regulate a wide range of processes in plants, ranging from growth and photosynthesis to reproductive development. In particular, JAs are critical for plant defense against herbivory and plant responses to poor environmental conditions and other kinds of abiotic and biotic challenges. Some JAs can also be released as volatile organic compounds (VOCs) to permit communication between plants in anticipation of mutual dangers.
"Axenic" - In biology, axenic describes the state of a culture in which only a single species, variety, or strain of organism is present and entirely free of all other contaminating organisms. The earliest axenic cultures were of bacteria or unicellular eukaryotes, but axenic cultures of many multicellular organisms are also possible. Axenic culture is also an important tool for the study of symbiotic and parasitic organisms in a controlled manner.Now that last defined term is interesting in that in studying the subject here of Trichoderma, we want no outside contamination of any other organism within our experiment. We want to observe the effect the Trichoderma fungi alone has on plants. Clearly the effects of Trichoderma appear to provide multiple positive benefits. But now comes the tricky part. It's one thing to have it work in a lab, but how well will these same functions and benefits work in the field. Well, you can read on further down below. However, when any of these Mycorrhizal Inoculent producing companies are experimenting for that magical powder or solution as an inoculum, sometimes the desired results may not translate as well in the field tests as they did on paper in the Lab. Why ?? Because once in the field, that single organism that did all those wonderful things now has to compete with a plethora of other like organisms. While there may have some colonization of a certain specific target species of your favourite fungi on some roots, the effects could be minimal because of the competition already occupying root space as compared to if the fungi were alone. So there are going to be many more challenges in research and experimentation on finding a beneficial as well as tough enough fungi to fit into your magic inoculum product. Can you imagine where we'd be if science decades ago had spent more time observing, admiring and replicating nature as opposed to viewing it as flawed, imperfect and so badly designed that the route taken was to genetically manipulate imaginary improvements to plants while totally ignoring Nature's optimization performance enhancing after market add ons ?
The other two terms up there Auxins and Jasmonic Acids in which the Trichoderma can act as an inducer for the production of these growth enhancing and pathogen suppressing immune system tools are also wonders to behold, especially in the light of the successful experiments mentioned below. Drought Stress tolerance enhancers, growth and nutritional enhancers, aside from the pathogen suppressing elements against diseases and insect herbivore attacks. Why Science is still trying to decipher how the hormonal signalling network behind the systemic resistance induced by Trichoderma harzianum in tomato actually works. Yes, where would our world now be if the direction of Science went here instead of artificial money making industrial opportunities ? One thing is for sure, most of the industrial giants would be so giant, especially if Farmers ever gained the knowledge that they could accomplish successes by changing practices and making money by not having to fork over hard earned money to others for basic substandard environmental destroying products.
Here is an interesting example below of a company that has tested Trichoderma on Corn in the field for drought stress.
The company ABM with Dr Gary Harman PhD is a new one for me. I have never used their product and I am not necessarily endorsing it. You will have to do further homework. What interests me here in the video below are the results of drought stressed Corn left to it's own without the aid of further water supplementation where two scenarios of one control or untreated field and one field treated with this company's Trichoderma product. It's four minutes long and you'll have to watch it to the end to get the entire story. I've also posted a very wonderful easy to follow article written by Gary Harman which should illuminate further the benefits of this one particular Fungi.
Frankly I find this stuff fascinating every time I stumble across other folks with kool experiences. But there are some precautionary things you need to keep in mind. People want an instant acting magic powder or liquid Elixir to perform insta-poof results on their plants which often times is all they get from the agro-chemical companies. This isn't about instantaneous results. I've given this illustration before. A person who becomes a sports star, Hollywood Celebrity or political darling doesn't do so over night. They work hard at their career often sacrificing a real normal life, even family to obtain that immortality of celebrity status. Many take decades accomplishing this. Then in a moment of weakness, they do something controversial, stupid and outrageous behaviour-wise and their career slips into the toilet. It may take a very long time to heal wounds and erase the damage done almost overnight. Just maybe they can rescue their career out of the toilet. The natural world is the same. It has taken the natural world 10s of 1000s of years to develop an Earth into a beautiful paradisaic state. And yet in little over 100+ years (1914) of so-called scientific enlightenment to the present, our Earth and it's various life sustaining mechanisms are now on the brink of total collapse. My field of interest has always traditionally been ecto-mycorrhizal fungi and experimenting with various species of these fungi with specific species of plants and under varied environmental conditions. Delving into the Endo-mycorrhizal world and all other associated beneficial organisms has really been a further eye opening reward. The results not just through reading, but practical application which have brought me personal successes has been rewarding.
|Illustrative animation by chronotext.org|
But on the intelligent side of epigentics and it's work on triggering specific switches within even the fungal organism Trichoderma itself, this is where the subject becomes much easier to understand from an organized mechanisms standpoint and practical application by means of biomimicry. Google this organism through various scenarios of environments and plants it colonizes and all manner of epigenetic schematic effects come up. Depending on soil environment and the specific plant it chooses as it's host, there are a number of different things it can accomplish and influence through the biological messaging network. This is the way the plant health care industry should have pursued things years ago and they chose not to for strictly financial gain reasons. It's important for landscapers, gardeners and farmers to understand even to a limited degree of how their practices [Good, Neutral or Bad] can and do have an important epigenetic gene expression effect on their living landscape. For example, in the modern conventional excessive use of synthetic chemical fertilizers, there is an epigentic effect on a host plant shutting down it's signalling chemical compounds which triggers the ongoing colonization message to mycorrhizal fungi which in effect says, "Hey I need you." Too much synthetic fertilizers inform the plant that an abundance of nutrition is available and the services of the mycorrhizal fungi are no longer needed. The chemical signalling is shut down and the fungi disconnect. In so doing the plant now has a far limited root absorption infrastructure and has become totally dependent on regular feeding program by the gardener, landscaper or farmer. It is also now further vulnerable to pathogens [soil & air borne] since the regulatory mechanisms and chemical inducer network provided by the fungi are no longer available to trigger alerts ahead of time. This works in the agro-chemical company's favour because a host of other chemicals like herbicides, fungicides and insecticides [in general more Pesticides period] must be employed to compensate for the loss of the fully functioning plant immune system. Basically your plant is now on life support and dependent on you more than ever now. Bottom line, inputs go up and profits go down. It just depends on how much a person is willing to learn and manage their program to the most sustainable outcome potential possible.
Real quick, I'll just stop here with one further easy to understand reference and not burden you with any more material than can be absorbed.
Some Easy to understand References
This was a great reference with easy to understand terminology and illustrations. It apparently was created by Dr Gary Harman when he was with Cornell Iniversity and BioWorks, Inc., Geneva, New York