Trichoderma has been proven as an excellent biocontrol fungus in soil ecosystem and has been widely used by farmers making it an important component in organic farming. It has several mechanisms of action and has multifarious effect on crop growth and production. In this regard, I have following 3 queries; comments from expert are invited.
1. Among the various modes of action of Trichoderma, production of extracellular enzymes such as chitinases and glucanases is well known. Both the antagonist (Trichoderma) and pathogen cell wall is made up of chitin. Then, how Trichoderma distinguishes self versus non-self in parasitism.
2. When we apply Trichoderma in soil, we noticed that even fruit trees on the verge of wilting get recovered in 20-25 days. In the tropical condition, the pathogen associated with wilt has been various spp. of Fusarium such as F. oxysporum and F. solani etc. As we know these wilt pathogen obstruct the transport system of plant by plugging the vascular bundles. Now the question is, how deep seated mycelium of Fusarium has been degraded and the water and nutrient flow became normal so that plant recovered when the biocontrol fungi, Trichoderma is in soil/ rhizosphre. What mechanism is assigned to such recovery of plants by application of Trichoderma?
3. We know that in soil, there are many other beneficial fungi like several species of Aspergillus that help in degradation of soil organic matter and enhances availability of nutrients by way of production of organic acids. Is there any report of antagonism of these beneficial species by Trichoderma in soil?
For Self and Non Self Recognition Please see This Paper Link http://www.ncbi.nlm.nih.gov/pubmed/21873410. In Soil very complex interactions are going on. The microorganisms may be in positive relationship or Negative to each other and so in case of Trichoderma also...
Vinod , very intelligently placed question. Regarding Trichoderma distinguishing between self versus non-self in parasitism , there is a strong possibility of two predominant enzymes chitinases and gluconases having multiple co-factors to be able to sense the differential behaviour . My second response to how trees started responding to trichoderma inoculation , i feel it is dynamics of Trichoderma within rhizosphere versus endosphere , latter displaying much better compatibility ..some thoughts please...
These were the queries in my mind but so far I couldn't find satisfactory answer . The possibility suggested by Dr. Anoop K Srivastava sir may exits. In a review available on self vs. non self fugal cell wall degradation, authors have hypothesised that substrate accessibility due to cell wall protection in healthy hyphae vs. deprotection during mycoparasitic attack, hyphal ageing and autolysis could be the mechanism involved.
Sir,
Your queries may be answered by the following review:
"Trichoderma: the genomics of opportunistic success"- Nature Reviews Microbiology 9, 749-759 (October 2011) | doi:10.1038/nrmicro2637
Kindly go through the following link also:
http://www.osti.gov/scitech/servlets/purl/1165278/
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