Scientists uncover hidden chemical language connecting plants, microbes, and soil life

Researchers are shedding new light on a largely invisible communication system operating beneath the Earth’s surface. A review published in Communications Earth & Environment argues that volatile organic compounds (VOCs) serve as a chemical language connecting plants, microbes, fungi, nematodes, and other soil organisms, shaping interactions that affect crop productivity, disease suppression, and ecosystem functioning.

The study, led by scientists from the Chinese Academy of Tropical Agricultural Sciences, the University of Copenhagen, the United Arab Emirates University, and the Netherlands Institute of Ecology, synthesizes current knowledge on how VOCs move through soil and influence biological processes. The authors suggest that understanding these chemical signals could open new opportunities for sustainable agriculture and climate-resilient farming systems.

A chemical communication network underground

VOCs are small molecules produced by plant roots, bacteria, fungi, and other soil organisms. Because of their low molecular weight and high volatility, they can travel through air- and water-filled pores in soil, allowing organisms to communicate without direct physical contact.

The researchers describe VOCs as a fundamental component of the “hidden networks” operating belowground. These compounds can help organisms identify neighbors, attract beneficial partners, deter competitors, and prepare for environmental stress. While previous research has focused heavily on visible aboveground interactions, the review suggests that similar communication systems are active beneath the soil surface and may be equally important.

Evidence from experimental studies indicates that root-produced VOCs can attract beneficial bacteria, influence neighboring plants, and even alter the behavior of nematodes and other soil organisms. However, most existing research has been conducted under laboratory conditions, leaving questions about how these interactions function in natural field environments.

Plant roots may warn neighboring plants

According to the review, plant roots release distinct VOC blends that reflect their physiological condition and environmental stresses. Neighboring plants can detect these signals and adjust their own responses accordingly.

In one example cited by the authors, stressed Norway spruce plants increased root VOC emissions, prompting nearby European beech plants to activate defense-related responses before herbivore attacks occurred. Other studies have shown that root-emitted compounds can influence plant chemistry, nutrient allocation, and susceptibility to pests.

The findings suggest that plants may possess a form of early-warning system that enables them to anticipate threats through chemical cues from neighboring roots. However, the molecular mechanisms behind this communication remain poorly understood.

Microbial signals could boost crop resilience

The review also highlights the role of microbial VOCs in promoting plant growth and resilience. Certain compounds produced by beneficial bacteria have been shown to improve nutrient uptake, stimulate root development, and activate plant defense pathways.

Researchers note that VOCs emitted by species of Bacillus, Pseudomonas, and other beneficial microbes can help plants tolerate drought, salinity, and pathogen attacks by influencing hormonal signaling and physiological processes. Some microbial VOCs can even serve as nutrient sources, such as sulfur-containing compounds that plants can absorb and utilize.

The authors argue that these findings could eventually support the development of biological crop protection strategies that rely on microbial communication rather than conventional chemical inputs. However, they caution that most evidence comes from controlled laboratory experiments and must be validated under realistic agricultural conditions.

VOCs shape microbial communities and predator-prey interactions

Beyond plant-microbe interactions, VOCs also influence relationships among soil microorganisms themselves. Studies reviewed by the authors show that bacterial and fungal VOCs can suppress pathogens, stimulate beneficial microbes, alter gene expression, and influence biofilm formation.

The compounds also play a role in soil food webs. Predatory nematodes, protists, and mites use VOCs as chemical trails to locate prey, while prey organisms may use the same signals to detect threats and adjust their behavior. This chemical exchange creates a complex network of interactions that helps regulate soil biodiversity and nutrient cycling.

Researchers suggest that VOC-mediated communication may represent a key mechanism linking microbial communities, plant roots, and higher trophic levels across entire soil ecosystems.

Climate change and farming practices may alter soil conversations

The review identifies climate change as a major factor that could reshape soil VOC dynamics. Temperature, moisture levels, fertilizer use, pesticide residues, and microplastic contamination all have the potential to affect VOC production, transport, and degradation.

Drought conditions, for example, have been shown to reduce microbial carbon respiration while increasing VOC emissions, potentially altering how soil organisms communicate and process nutrients. Similarly, nitrogen fertilization can modify microbial communities and change the composition of VOC blends in agricultural soils.

Microplastics present another emerging concern. The authors note that plastic residues can absorb VOCs, alter soil structure, and release their own volatile compounds, potentially disrupting natural chemical signaling networks.

Major knowledge gaps remain

Despite growing evidence for the importance of VOCs, researchers acknowledge that significant questions remain unanswered. Most studies have examined individual compounds in simplified laboratory settings, whereas real-world soils contain complex mixtures of VOCs produced by diverse communities of organisms.

The authors call for more field-based research using advanced analytical tools, isotope tracing, and genetic techniques to better understand how organisms perceive VOCs, how signals move through heterogeneous soils, and how communication networks respond to environmental change.

They conclude that deciphering this underground chemical language could provide new tools for enhancing crop health, improving biological pest management, and building more resilient agricultural systems in a changing climate.

Source: Nature