Approaches to understanding auxin action.

The effects of auxin on plant growth and development have been studied for decades, but the molecular mechanisms of auxin action remain unknown. These mechanisms have primarily been investigated by characterization of auxin physiology mutants and analysis of auxin-binding proteins and auxin-regulated genes. These efforts are now converging, since some mutants have recently been shown to have altered expression of specific auxin-binding proteins and auxin-regulated genes. The features of these proteins and genes are providing the first tantalizing clues to the organization of auxin signal transduction pathways.