A synthetic hormone acts like a remote control to grow specific plant cells while leaving their neighbors alone.

A custom-made molecule and a matching modified receptor bypass the internal natural signaling of plants entirely. Plants usually rely on a natural hormone called gibberellin that floods through their tissues in unpredictable waves to signal growth. Researchers can now flip a biological switch in just the root's outer layer without affecting the core of the plant. This precision proves that root expansion is a coordinated effort managed by specific cell layers rather than a general reaction to the environment. Farmers and scientists might eventually use these synthetic triggers to design crops that grow deeper roots on command during a drought.