GOING THE DISTANCE WITH AUXIN - UNRAVELING THE MOLECULAR-BASIS OF AUXIN TRANSPORT

Auxin represents one of the most important classes of signalling molec ules described in plants. Auxins regulate several fundamental cellular processes including division, elongation and differentiation. Indole- 3-acetic acid (IAA), the principal form of auxin in higher plants, is first synthesized within young apical tissues, then conveyed to its ba sal target tissues by a specialized delivery system termed polar auxin transport. The polarity of IAA movement represents one of the most no vel aspect of auxin signalling. IAA transport has been demonstrated to involve auxin influx and efflux carrier activities. The adoption of a mutational approach in the model plant Arabidopsis thaliana has led t o the identification of a number of genes which encode components for, or regulate the activity of, the auxin transport machinery. This pape r will review the advances being made in identifying and characterizin g these auxin transport-related gene products and discuss their import ance within the context of Arabidopsis development.