Chitosan & Mycorrhiza

(This is a summary. The full text including references is available on request.)

There are various studies on the influence of chitosan on mycorrhiza. Generally positive effects on the growth of mycorrhizal fungi and roots of the associated plants could be observed, followed by better plant development and harvest. The enzymes (chitinase and chitasanase) produced by plants to resist infections are specifically effective against the cell walls of phytopathogenic fungi but are inoperative against the cell walls of mycorrhiza. No harmful increase, for mycorrhiza, in chitinases and chitosanases production by soil inhabiting bacteria after treatment with chitosan was observed. The increased lignification of plant cell walls after treatment with chitosan is also not a problem for mycorrhiza fungi of arbuscular or ectotrophic because both engage the roots of plants near the root cap where the rhizodermis is still intact and forms root hairs. At this part of the root the exodermis is yet not lignified so the mycorrhiza can engage their linkage with the plants root cortex unobstructed. This is not altered due to treatment with ChiProPlant®.

1. Two german patents, one for a chitosan-based plant strengtheners and one for a fertilizer, state positive effects of chitosan on both mycorrhiza and plants – definitely no obstruction could be observed rather an encouragement also of mycorrhizal growth.
   1. "Chitosan [...] stimulates the plant's natural defence system, leading to genetic, physiological and biochemical reactions."
   2. "Interesting is the balancing effect of chitosan on beneficial organisms such, as mycorrhizae which are not affected, but encouraged."
2. Chitosan is enzymatically degraded and changes the living conditions in a disadvantaging way for soil-borne phytopathogenic organisms. Under these conditions the beneficial microorganism, such as mycorrhiza, can easily prosper.
   “[...] this biopolymer (chitosan) is composed of polysaccharides that stimulate the activity of beneficial microorganisms in the soil such as [...], mycorrhiza and rhizobacteria. This alters the microbial equilibrium in the rhizosphere disadvantaging plant pathogens.”
3. A scientific paper from the Botanic Institute at the University of Basel in Switzerland states that mycorrhizal fungi are not attacked by the chitinases or chitosanases produced by the plant to defend itself against phytopathogenic organisms.“While infection of the root pathogen [...] was inhibited, formation of arbuscular mycorrhiza [...] was not affected at all [...]. This indicates that the structure of the cell wall of mycorrhizal fungi is resistant to the attack of defense-related chitinases.”
4. The UFT (Zentrum für Umweltforschung und Umwelttechnologie) made a study on ChiProPlant and its effects on the growth of mycorrhiza. This study was carried out at the University of Bremen by Prof. Dr. W. Heyser and Dr. In-Ock Koh. Results show that the growth of mycorrhiza is in no way negatively influenced by the application of ChiProPlant. In fact the opposite is observable.
   For this study Pinus sylvestris and one of its mycorrhiza (Suillus bovinus) were used as test subjects. The pictures below show the seedlings 30 days after the treatment with ChiProPlant (concentration 1:4000). The seedlings show a vast increase in root growth and mycorrhizal development. 
   
   
   

   Mycorrhiza at Pine with Chitosan Treatment

   

   Mycorrhiza at Pine without Chitosan Treatment

5. The structure and function of chtinases and chitosanases are complex and with a great variety amongst the different enzymes produced by different organisms. The enzymes must be specified in order to break down mycorrhizal cell wall chitin and chitosan. “The distinction between chitinases and chitosanases is that chitinase specifically cleaves the N-acetyl-D-glucosaminidic bonds while chitosanase cleaves the β-D-glucosaminidic bonds. Chitosanases are able to hydrolyze all kinds of linkages in chitosan except the GlcNAc-GlcNAc bond.”
6. A study with arbuscular mycorrhized potato plants shows that chitosan (in this study called NOCC) is effective against late blight (Phytophthora infestans) without attacking the mycorrhiza. Chitosan was compared to a conventional fungizide. The yield for chitosan treated plants was increased and the disease development was delayed.

“At harvest, yields for the [conventional fungicide]-NOCC, NOCC and AMF-NOCC treatments were significantly higher than the un-sprayed, non-mycorrhizal control and were not significantly different to the [conventional fungicide]-sprayed control. The results are discussed in relation to the production of seed potatoes for organic (ecological) growers.”