Title : Mycorrhizae and their role in climate resilience in agricultural systems
Abstract:
Mycorrhizal associations are ancient symbiotic relationships between fungi and plant roots and may predate the emergence of terrestrial plants. These associations have played an important role in plant adaptation to terrestrial environments. Arbuscular mycorrhizal (AM) fungi form extensive hyphal networks within soil and establish symbiotic relationships with the majority of terrestrial plant species. In exchange for plant-derived carbon, AM fungi enhance the acquisition of nutrients and water and influence the biological and chemical properties of the rhizosphere. Plant roots release a diverse range of organic compounds, collectively known as root exudates, which modify rhizosphere chemistry and influence microbial community structure. These compounds can alter local pH, stimulate beneficial microorganisms and contribute to interactions that suppress soil-borne pathogens. Mycorrhizal colonisation can modify the quantity and composition of root exudates, thereby influencing bacterial and fungal communities within the mycorrhizosphere. The resulting plant–fungus–microbiome interactions contribute to nutrient cycling, soil aggregation and overall plant health. The increasing economic and environmental costs associated with synthetic fertilisers, pesticides and fungicides have intensified interest in AM fungi as a component of more sustainable agricultural systems. Intensive cultivation and repeated soil disturbance can disrupt soil aggregates, accelerate organic carbon losses, reduce biological activity and impair nutrient cycling. Soil compaction and degradation can subsequently increase crop vulnerability to water stress, disease and nutrient deficiency, often increasing reliance on chemical inputs. In contrast, biologically active soils containing abundant microbial communities and intact fungal networks can support improved soil structure and nutrient availability. The extensive hyphal network produced by AM fungi substantially increases the effective volume of soil explored by plant roots. This facilitates access to relatively immobile nutrients, particularly phosphorus, as well as micronutrients and water beyond the immediate root zone. AM fungi also contribute to soil aggregation through the formation and stabilisation of soil aggregates, thereby improving porosity, water infiltration and water-holding capacity. Mycorrhizal associations can enhance plant growth through improved nutrient acquisition, modulation of plant hormonal signalling and the induction of systemic resistance against pathogens. Mycorrhizal plants may maintain higher photosynthetic activity and greater physiological function under environmental stress than non-mycorrhizal plants. AM symbiosis can also improve plant water relations and contribute to drought tolerance by increasing access to soil water and influencing plant responses to water deficit. Global food security increasingly depends on maintaining productive soils while reducing environmental impacts. AM fungi therefore have considerable potential as biological fertilisers or bioinoculants, improving the efficiency with which crops acquire nitrogen, phosphorus and other mineral nutrients. Their integration into organic, regenerative and conventional agricultural systems could contribute to improved soil health, nutrient-use efficiency, drought resilience and crop productivity while reducing dependence on synthetic chemical inputs. AM fungi represent an important biological technology for developing more resilient and sustainable agricultural systems capable of supporting future global food security.
