Plants growing close together can warn one another about stress, helping nearby plants survive conditions that would otherwise cause serious damage.
In experiments with thale cress (Arabidopsis thaliana), researchers grew plants either in isolation or packed so closely that their leaves touched. When exposed to intense light, isolated plants suffered severe damage, while crowded plants coped much better. Within an hour, densely grown plants activated more than 2,000 genes linked to protection against different stresses, whereas isolated plants showed little change in gene activity.
The findings suggest that stressed plants send warning signals to their neighbours. The study showed that crowded plants released hydrogen peroxide, a molecule known to trigger defence responses. For the first time, researchers found evidence that hydrogen peroxide can pass between plants, acting as a shared alarm signal that prepares surrounding plants for incoming stress.
