Plants Adjust Their Growth Strategies by "Eavesdropping" on Neighbors' Scents

New research shows that plants can sense their neighbors' growth rates through aromatic cues called volatile organic compounds (VOCs) and then adjust how much energy they invest in their own growth or defense strategies through responsive gene expression. VOCs are carbon-based chemicals that readily mix into the air and are widely produced by plants to communicate with herbivores, pollinators and even other plants. These compounds, which are also the source of the wide variety of pleasant scents produced by plants, are frequently used in the production of perfumes, cosmetics, food and cleaning products.

Beyond alarm signals in plants
Until now, most research on plant-derived VOCs has focused on damaged plants emitting alarm-like chemical signals to warn neighbors to activate their defenses against herbivores. This new study, published in the Journal of Experimental Botany, reveals a previously unknown role of healthy plant VOCs in competitive growth environments. Dr. Velemir Ninkovic from the Swedish University of Agricultural Sciences says: "Healthy, undamaged plants continuously leave their own unique chemical 'fingerprints' in the air, and neighbors effectively read these signals not only to adjust their defenses, but their entire growth strategies. It's like continuous conversation between neighbors; the discovery that these background VOCs can reshape growth and gene activity adds a new dimension to our understanding of plant communication."

Barley laboratory experiments
Dr. Ninkovic and his team conducted two laboratory experiments with three different barley (Hordeum vulgare) varieties growing at different rates (slow-growing "Fairytale", medium-growing "Luhkas" and fast-growing "Salome") and exhibiting different VOC profiles to better understand the role of these VOCs from healthy plants. Since barley is one of the world's most important cereal crops, the findings on how this plant grows, defends itself and interacts with neighboring plants have direct practical significance for agriculture. The slow-growing Fairytale and fast-growing Salome varieties were exposed to VOCs from all three varieties; after 25 days, the plants' physical characteristics and changes in gene expression were analyzed to measure effects on growth and defense strategies.

How do plants adjust their growth?
The researchers found that exposure to different VOC profiles led to changes in total plant biomass; VOCs from plants with similar growth rates showed negligible effects. Dr. Ninkovic emphasizes: "VOC-receiving plants adjusted their growth according to the competitive pressure signaled by their neighbors' scent: they grew more when exposed to a fast-growing neighbor and less when exposed to a slow-growing one. This effect was observed consistently across all plant parts including leaves, stems and roots, rather than just the plant redistributing resources between parts." Genetic analysis revealed that biomass changes were linked to alterations in pathways related to growth and defense. Shifts toward the slow-growing Fairytale VOC profile were associated with upregulation of stress response genes providing protection against herbivores and downregulation of cellular transport and DNA replication genes, while the opposite pattern was observed for shifts toward the fast-growing Salome VOC profile.

Source: Publication details
Volatiles released by undamaged plants mediate the adaptive growth strategies in neighbors, Journal of Experimental Botany (2026). DOI: 10.1093/jxb/erag252. academic.oup.com/jxb/advance-a … /jxb/erag252/8696139 . On bioRxiv: DOI: 10.1101/2025.08.15.670058 / Journal information: Journal of Experimental Botany,  , bioRxiv  / https://phys.org/news/2026-05-growth-strategies-spying-neighbors-scents.html