Do leaves and soil speak in scents?

Soil is far more than a medium for crops to anchor their roots take root; it is a vast and intricate living network. Crop health and yield depend not only on above-ground growth, but also on the soil environment and microbial communities surrounding the roots.

On August 15, Science published a research article by Professor Prof. XU Jianming and Researcher Prof. HU Lingfei from Zhejiang Universitys, titled “Linalool-triggered plant-soil feedback drives defense adaptation in dense maize plantings.” The study reveals how linalool, a fragrant volatile compound released by maize leaves, accumulates in densely planted fields and triggers a cascade of soil-mediated defenses—a kind of transgenerational defensive “Great Wall” underground. This finding offers new insight into crop resilience under intensive farming and suggests greener, pesticide-free strategies for sustainable agriculture.

PhD students GUO Dongsheng and LIU Zilin of Zhejiang University, together with Jos M. Raaijmakers from the Netherlands Institute of Ecology, share first authorship ofon the paper.

The “sweet trouble” of high-density planting

Under the dual challenge of global food security and sustainable agriculture, high-density planting has become a cornerstone of modern agriculture, especially for crops like maize. While this practice boosts yield, it also brings a downside: crowded plants facilitate the spread of pests and pathogens, threatening both productivity and stability .

“This is the sweet but troubling paradox of dense planting,” XU Jianming explained. “We wanted to understand how crops adapt to such biological pressures.”

During their fieldwork in Hainan, XU Jianming’s team observed an intriguing phenomenon: Maize plants growing at the center of densely planted fields appeared healthier and more resistant to pests than those on the edges. Back in the laboratory, after ruling out factors such as light competition and root exudates, the researchers turned their focus to a floral-scented volatile—linalool.

“Linalool accumulates significantly under dense planting, likely because reduced airflow inside the canopy slows its dispersal,” explained HU Lingfei. The researchers discovered that this fragrance accumulated in the canopy, triggering jasmonic acid signaling in neighboring plant roots. This, in turn, promoted root secretion of a benzoxazinoid compound called HDMBOA-Glc into the rhizosphere, which enriched beneficial root-associated bacteria and reshaped the soil microbial community.

Maize “talks” to soil in the language of scents

The researchers discovered that linalool is more than a fragrance; it is also a chemical messenger linking plants with soil. This volatile triggers jasmonic acid signaling in neighboring maize roots, which in turn stimulates the secretion of a defensive compound, HDMBOA-Glc, into the soil. This chemical cue recruits beneficial rhizosphere bacteria, reshaping the soil microbiome in ways that favor plant defense.

In controlled lab experiments, linalool-enriched soils fostered microbial communities that boosted plants’ salicylic acid production and activated defensive pathways. The result was a closed feedback loop: plants release linalool, linalool modifies soil communities, and enriched microbes enhance the plants’ immunity.

“Linalool is natural, fragrant, and environmentally friendly,” said XU Jianming. “What surprised us most was that its effects extended across individuals and even across generations.”

The researchers found that soils exposed to linalool “remembered” the interaction. Even in crop rotations, subsequent plantings benefited from the defensive microbial legacy left behind.

When the team applied small amounts of linalool directly to the soil, the results were striking: rates of nematode infection, fungal disease, and viral infection all dropped, while fall armyworm feeding and growth slowed by 10–30 percent.

This suggests that linalool acts as both a natural immune booster for plants and a signaling molecule that cultivates a healthier soil ecosystem.

From field phenomenon to soil mechanism

“Soil is the foundation for plant survival. Any serious research must begin there,” said Hu Lingfei.

The team combined microbiomics, metabolomics, and molecular biology to trace the linalool effect from the canopy down to the rhizosphere. They used maize mutants and metabolic markers to map signaling pathways, and they isolated key bacterial strains to test their functions. The results revealed how soil microbes serve as critical intermediaries, reducing biological obstacles in densely planted fields.

The concept of plant volatiles as regulators has already extended beyond maize. Similar effects were observed in barley, suggesting broader applications across crops.

Looking ahead, XU Jianming envisions practical uses for the findings: “If we can manage linalool release or design microbial inoculants that mimic its effects, we could enhance crop defenses and stabilize yields—without pesticides. This offers great promise for future agricultural practices.”

The study has already drawn global attention. In the same issue of Science, Claude Becker, a biologist at Ludwig Maximilian University of Munich, wrote a Perspective article titled “The Scent of a Crowd”. He praised the work as “a major breakthrough” that connects aboveground plant signaling with underground microbial ecology.

Becker highlighted the study’s clear mechanistic chain, its integration of field and laboratory work, and its potential impact on sustainable farming. By showing how a single volatile compound can reshape the rhizosphere and fortify plants under stress, the team from Zhejiang University has opened a new chapter in plant–soil communication research.

Adapted and translated from the article by ZHA Meng
Translator: FANG Fumin 
Photos by ZHE Yin
Editor: HE Jiawen, ZHU Ziyu