The NAC transcription factor SOMBRERO controls auxin gradients for columella root cap maturation and turnover.

SOMBRERO (SMB) transcription factor is essential for maintaining auxin gradients and proper root cap development in Arabidopsis thaliana.

• Why it matters: Understanding how auxin gradients are established and maintained in the root cap is crucial for revealing mechanisms of root growth and environmental response, which are not yet fully understood.
• What they did: The study used transcriptomic profiling, EMSA, and promoter reporter assays to show that SMB binds to auxin-related gene promoters and modulates their transcription, affecting auxin homeostasis and signaling.
• The result: Disruption of SMB altered auxin biosynthesis, transport, and signaling, leading to impaired Golgi remodeling and border-like cell turnover, highlighting SMB's role in coordinating auxin dynamics with root cap maturation.