How do plant-derived aerosols influence plant interactions?

In response to herbivory, plants release volatile organic compounds (VOCs) into the atmosphere. These VOCs have a key role in plant-plant interactions. In this process, undamaged plants may detect warning signals from their damaged neighbors and prepare defenses.

Through chemical reactions, reactive plant VOCs turn into secondary organic aerosols (SOAs). In a new study, scientists at the University of Eastern Finland wanted to see if the ecological roles of VOCs continue even after they become SOAs.

The study showed that when large pine weevils damage Scots pine seedlings, they emit VOCs that defend nearby plants of the same species. This continues even after the VOCs are transformed into SOAs. The results suggest that the properties and abundance of SOAs are key to their biological impact.

This means that plant-derived SOAs can act as mediators of plant-plant interactions.

Professor James Blande, head of the Environmental Ecology Research Group, said, “A key novelty of the study is the finding that plants adopt subtly different defence strategies when receiving signals as VOCs or as SOAs, yet they exhibit similar degrees of resistance to herbivore feeding. This observation opens up the possibility that plants have sophisticated sensing systems that enable them to tailor their defences to information derived from different types of chemical cues.”

Professor Annele Virtanen, head of the Aerosol Physics Research Group, said, “Considering the formation rate of SOAs from their precursor VOCs, their longer lifetime compared to VOCs, and the atmospheric air mass transport, we expect that the ecologically effective distance for interactions mediated by SOAs is longer than that for plant interactions mediated by VOCs. This could be interpreted as plants being able to detect cues representing close versus distant threats from herbivores.”

Journal Reference:

1. Hao Yu, Angela Buchholz, Iida Pullinen, Silja Saarela, Zijun Li, Annele Virtanen, James D. Blande, Biogenic secondary organic aerosol participates in plant interactions and herbivory defense. Science, Vol 385, Issue 6714, 1225-1230 (2024), ISSN 0036-8075, DOI: 10.1126/science.ado6779