The system that controls gene expression by the plant signaling molecule auxin has deep evolutionary roots, and stepwise increases in system complexity shaped the highly diverse auxin response in land plants.
The auxin-sensitive Aux/IAA transcriptional repressors regulate approximately 35% of the annotated genes in Physcomitrella patens and exhibit complex interactions with both the activating and repressing ARF transcription factors.
HEC transcription factors control the timing of cell fate transitions in a dynamic stem cell system, allowing plants to adapt their developmental program to diverse environments.
Genetic analyses reveal that the TIR1/AFB auxin receptors have broadly overlapping functions throughout plant development, but that the AFB1 receptor has a specialized role in a rapid auxin response.
Rhythmic centrifugal waves of auxin traveling through the tissue provides high definition positional information to cells that is not only spatial but also temporal.