Plants growing close together can alert one another to environmental stress, improving their chances of survival. In experiments with thale cress (Arabidopsis thaliana), researchers found that plants grown in crowded conditions coped far better with intense light stress than those grown alone.
When exposed to strong light, isolated plants suffered significant damage and showed little change in gene activity. By contrast, crowded plants activated more than 2,000 protective genes within an hour, enabling them to withstand the stress. The findings suggest that a warning signal passed between neighbouring plants, triggering their defensive response.
The study identified hydrogen peroxide as the key messenger. While this molecule is known to activate stress defences within plants, this is the first evidence that it can move from one plant to another. By sharing this chemical signal, plants growing together can prepare collectively for harsh conditions, gaining a clear survival advantage.
