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 far better by rapidly activating protective mechanisms.
Within an hour, densely grown plants switched on more than 2,000 genes linked to defence against multiple stresses. Isolated plants showed little change in gene activity, suggesting they received no warning signal.
The study found that stressed plants released hydrogen peroxide, a molecule known to trigger defence responses. For the first time, researchers showed that this chemical can pass between plants, allowing neighbours to prepare for stress before damage occurs.
