A recent study published in Science has revealed that plant-derived secondary organic aerosols (SOAs) can play a role in mediating plant-plant interactions. The research, which was conducted by a team of chemical ecologists, plant ecophysiologists, and atmospheric physicists at the University of Eastern Finland, focused on the impact of volatile organic compounds (VOCs) released by plants in response to herbivore damage. These VOCs are known to serve as warning signals for undamaged plants, triggering defensive responses in nearby plants.
The study specifically looked at Scots pine seedlings that were damaged by large pine weevils, leading to the release of VOCs that activated defenses in neighboring plants of the same species. Surprisingly, the researchers found that even after the VOCs were oxidized to form SOAs, the biological activity persisted. This suggests that the elemental composition and quantity of SOAs may play a crucial role in determining their biological functions in plant-plant interactions.
One of the key findings of the study was the observation that plants appear to adopt subtly different defense strategies when receiving signals as VOCs versus as SOAs. Despite these differences, plants displayed similar degrees of resistance to herbivore feeding, indicating that they have sophisticated sensing systems that enable them to tailor their defenses to different types of chemical cues. This insight could have significant implications for understanding how plants respond to environmental threats.
According to Professor Annele Virtanen, who heads the Aerosol Physics Research Group, the formation rate of SOAs from VOCs, their longer lifetime compared to VOCs, and atmospheric air mass transport suggest that interactions mediated by SOAs may have a longer ecologically effective distance than those mediated by VOCs. This implies that plants may be able to detect cues representing close versus distant threats from herbivores, enabling them to adapt their defenses accordingly.
Overall, the study is expected to open up a new and complex research area for environmental ecologists and their collaborators. By gaining a better understanding of the role of chemical cues in structuring plant interactions, researchers may uncover new insights into the mechanisms that drive plant-plant communication and defense strategies. This research could ultimately contribute to efforts to better protect plant species from herbivore threats and enhance our understanding of the intricate relationships between plants in natural ecosystems.