Plants growing close together can warn one another about incoming stress, helping their neighbours survive conditions that would otherwise cause serious damage.
In experiments with thale cress (Arabidopsis thaliana), researchers grew plants either in isolation or packed closely so their leaves touched. When exposed to intense light stress, isolated plants suffered heavy damage, while crowded plants coped far better. Within an hour, densely grown plants activated more than 2,000 genes linked to protection against multiple stresses, whereas isolated plants showed little change in gene activity.
The findings suggest that stressed plants send warning signals to nearby neighbours. The study identified hydrogen peroxide as the key messenger. While already known to trigger defence responses within individual plants, this research shows for the first time that hydrogen peroxide can pass between plants, allowing them to prepare collectively for environmental stress.
