The tree knows the signal for help

When damaged by fungi or harmful bacteria, leaves can "call" the roots to ask for help. After receiving the signal, the roots secrete an acid that attracts beneficial bacteria.

"Plants are smarter than we think. When plants are attacked by harmful fungi or bacteria, their roots always know how to seek outside help , " said Harsh Bais, Dai's expert on plants and soil. Delaware (USA), said.

To investigate this problem, Harsh Bais and colleagues track the leaves of Arabidopsis thaliana - a small flower. When attacked by Pseudomonas syringae, their metabolism is significantly reduced.

However, thanks to a bacterium called Bacillus subtilis, the roots of the plant remain healthy.

Enlarged image of Arabidopsis thaliana root.The protective film created by Bacillus subtilis is marked in green.Photo: Livescience.

Farmers often bring Bacillus subtilis into the soil to increase their tolerance to disease. This bacterium produces a membrane with antimicrobial properties around plant roots.

The team used special tools to monitor the process of signaling the rescue from leaves to roots of plants. They found that, after receiving the signal, the roots responded by secreting malic acid - a carbon-rich chemical.

According to Harsh Bais, all plants have the ability to synthesize malic acid themselves, but that only happens under certain conditions and conditions. In the experiments, experts found the roots of Arabidopsis thaliana secreted acid to attract Bacillus subtilis.

Harsh Bais and his colleagues will investigate the nature of the signal that leaves send to the roots when the tree is attacked.