Synthetic activation of gibberellin signalling reveals spatial coordination of root growth.

Coordinated GA signalling in the Arabidopsis root endodermis and epidermis is required for full root elongation, revealing spatial coordination across root layers.

• Why it matters: GA signalling in the endodermis promotes root elongation, but how other root layers contribute—and how GA activity is spatially organized—remained unclear.
• What they did: The study engineered a synthetic GA (sGA) with little or no binding to endogenous GID1 and a modified GID1 (mGID1) that selectively recognizes sGA, enabling cell-specific activation in vivo.
• The result: Distal patterns of GA signalling and GA biosynthetic enzymes support a model where bioactive GAs are transported from GA3ox-expressing tissues to the endodermis and epidermis to coordinate root elongation.