Ramalka H. Kasige, Ximena Cibils-Stewart, Adam Frew, and Scott N. Johnson from Western Sydney University in Australia, discuss their article: Interactions between beneficial fungi and plant silicon: A review
Plants are continually exposed to stresses — from drought, salinity, and metal toxicity to herbivores and pathogens. To withstand these challenges, they employ multiple strategies, including forming mutualistic associations with beneficial fungi and accumulating silicon (Si) in their tissues. Both are well-recognised for their independent roles in plant defence, but only recently have researchers begun to explore their combined effects. Our mini review synthesises four decades of literature to assess how Si and fungi interact, the mechanisms underpinning these interactions, and their potential applications in agriculture and ecology.
The power of partnerships
This review highlights Arbuscular mycorrhizal (AM) fungi and Epichloë endophytes as key beneficial fungal symbionts. Although many fungal endophytes exist in nature, Si research has primarily focused on Epichloë species, particularly in the context of defence against insects in grasses. AM fungi colonise plant roots and improve the uptake of water and nutrients, while Epichloë endophytes live within grass shoots and can enhance host defences. Silicon, absorbed by roots as monosilicic acid, accumulates in plant tissues, strengthening structural barriers and modulating defence responses in plants. Independently, both Si and fungi can improve plant tolerance to stress, but in combination they can be even more effective.
We found that AM fungi often enhance Si uptake, particularly when soil Si levels are low, which is a crucial benefit for species that are naturally poor accumulators. Conversely, Si supplementation can increase fungal colonisation in roots, creating a two-way relationship. While most Si research has focused on AM fungi, emerging evidence suggests that Epichloë endophytes may also increase foliar Si levels in grasses, boosting resistance to herbivores.
Mechanisms of interaction
AM fungi enhance Si uptake through root modifications, silicate dissolution in soil, upregulation of Si transporters, and stimulation of transpiration. They also activate defence pathways such as jasmonic acid signalling, which directly links to Si-based defences. Epichloë endophytes appear to increase vascular bundle density, influence host defence responses, and alter transpiration, all supporting greater Si accumulation. In turn, Si can promote fungal colonisation by stimulating root growth, increasing carbon availability, and modifying cell walls.
Synergy under stress
Across 35 studies that tested Si and beneficial fungal partnerships (AM & Epichloë endophyte), nearly three-quarters reported beneficial outcomes. Under abiotic stresses such as drought, salinity, or heavy metal exposure, plants performed significantly better when provided with both Si and beneficial fungi. Together, they improved nutrient uptake, enhanced antioxidant activity, and protected photosynthesis, resulting in healthier growth and higher yields.
Under biotic stresses, results were more variable but still encouraging. Si addition and beneficial fungi together often reduced herbivore feeding efficiency and growth rates, acting as dual defences. However, outcomes depended on the type of fungus, plant species, and even the feeding guild of the insect.
Why this matters
As climate change intensifies pressure on agriculture, the need for sustainable and environmentally friendly approaches is increasingly urgent. Silicon is inexpensive, widely available, and safe, while beneficial fungi are already used as biofertilisers and biostimulants. Understanding their interactions offers a pathway to more resilient crops and reduced reliance on synthetic chemicals.
Looking ahead
Despite the encouraging results, there are many important questions unanswered. Research has focused mainly on abiotic stress, with fewer studies examining effects on herbivores or plant community dynamics. There is not much evidence on how different beneficial fungi, soil conditions, or plant families shape the outcomes. Expanding this work into field studies and multispecies systems will be key to unlocking the full potential of Si–beneficial fungal partnerships.
For now, the evidence is clear: when Si and beneficial fungi team up, plants gain powerful allies. Harnessing these natural defences could support more sustainable agriculture in an increasingly stressful world.
