04/04/2023
The microbiomes of wild plants.
Plant roots contain large and diverse communities of bacteria, when grown naturally (ie in a diverse environment without fertiliser) they have a distinct and unique microbiome profile. As an example, let’s look at Yarrow (Achillea millefolium) used as a medicinal plant for digestive disorders, ulcers, colic, diarrhea, bloating, and constipation. Yarrow contains a spectacular array of secondary active plant metabolites such as flavonoids, phenolic acids, coumarins, terpenoids, monoterpenes, sesquiterpenes, diterpenes, triterpenes) and sterols. All of these are recognised for their health-providing, disease-treating properties, and production is stimulated in the soil as follows.
1. Soil bacteria called Rhizobiales first colonise the plant roots, secreting proteins, and metabolites (by-products), helping the plant to acquire nutrients and stimulating it to produce a wide range of polyphenolic secondary plant compounds. The plant uses these chemicals in defence against stress, radiation, and predators (being eaten by insects or horses) and by reducing pathogenic bacteria. The bacteria then travel to all parts of the plant above ground where they may be ingested by the horse.
2. The soil phytobiome of yarrow also contains bacteria from the family of alphaproteobacteria which make nitrogen available for the plant, reducing the need for fertilisers.
3. A third group of predominant bacteria in the soil are called bio control agents, this group produces toxins that are transferred through a powerful nano- weapon system able to kill pathogenic fungi, oomycetes, and bacteria. They signal to the host plant to trigger a system called immunity pathway- induced specific resistance, the plant then manufactures higher levels of antimicrobials, which find their way into the gut of your horse and continue to be a benefit!
Lucke, M., Correa, M. G., & Levy, A. (2020). The role of secretion systems, effectors,
and secondary metabolites of beneficial rhizobacteria in interactions with plants and microbes. Frontiers in Plant Science, 11, 589416.
Sauer, S., Dlugosch, L., Kammerer, D. R., Stintzing, F. C., & Simon, M. (2021). The microbiome of the medicinal plants Achillea millefolium L. and Hamamelis virginiana L. Frontiers in Microbiology, 12, 696398.