Auxin in action: signalling, transport and the control of plant growth and development.

Hormones have been at the centre of plant physiology research for more than a century. Research into plant hormones (phytohormones) has at times been considered as a rather vague subject, but the systematic application of genetic and molecular techniques has led to key insights that have revitalized the field. In this review, we will focus on the plant hormone auxin and its action. We will highlight recent mutagenesis and molecular studies, which have delineated the pathways of auxin transport, perception and signal transduction, and which together define the roles of auxin in controlling growth and patterning.