Mycorrhizal – Rhizosphere Interactions

Plant-root interfaces or rhizospheres, are inhabited by a unique population of microorganisms. Some known as arbuscular mycorrhizal fungi (AMF) commonly form symbiotic relationships with plants AMF assist in obtaining water, phosphorus and other micronutrients from the soil and in return receive carbon sustenance in the form of fatty acids from the plant. Shared mycelial networks between plants can transmit signals from insect damaged plants, altering volatile organic compounds in neighbouring plants to repel insects and attract parasitoids. Shared signals can also elicit plant defence priming in roots and leaves. Rhizosphere soil in AMF-colonised plants have greater soil aggregate stability and better water retention, organic carbon input and sequestration. Other rhizosphere organisms such as bacteria and earthworms, can also positively influence mycorrhizal interactions with plants.

AMF mycelia penetrate root cells from an external network extending beyond the plant root system. Increasing surface area for soil interactions, this facilitates the carbon-for water and nutrient symbiotic exchange and inter-plant signalling systems. Root exudates change and further stimulate beneficial changes in the rhizosphere’s microbial composition. Plant health, growth and pathogen resistance are stimulated when mycorrhizal fungi interact with the general microflora, or with specific microbes such as symbiotic nitrogen-fixing bacteria, nutrient solubilizing bacteria, fungal and bacterial biocontrol agents, and other fungi. AMF indirectly support a healthy soil community of living organisms balancing soil chemistry, physics and biology for optimum crop growth. Biofertilisers containing AMF, biostimulants and beneficial bacteria are commercially available in granular form for drilling and broadcasting.

Replace important soil beneficial microorganisms lost during tillage systems and crop rotations. Known benefits of stable AMF populations or biofertilizer use to replenish them are yield increases through better crop health and disease resistance, better moisture retention in soils by reduced compaction, reduction in traditional fertiliser use and runoff and increased ROI. Research at Leeds University is also identifying AM competent wheat cultivars.

https://www.nature.com/scitable/knowledge/library/the-rhizosphere-roots-soil-and-67500617/

https://www.rothamsted.ac.uk/news/“exciting-biology”-rewrites-text-books-uncovering-plants’-high-fat-diet-fungal-benefactors

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.12788

http://smart.plantworksuk.co.uk/soil-management/#p=12