Abstract
Considering the essential role of hormone auxin in plant development it is obvious that its directional transport is the matter of scientific research already many years. Recent progress in molecular biology approaches has contributed fundamentally to our understanding of mechanisms involved in the auxin transport.
Number of evidence exists on the role of auxin in the setting of developmental cues with the assistance of several auxin-transporting mechanisms. Localized and physiologically active levels of auxin maxima are major determinants for triggering various developmental events and therefore this molecule is often called the morphogen.
Auxin is passing through control mechanisms to maintain the optimum concentration in plant tissues. Among the major control mechanisms are permanent or reversible auxin conjugation, degradation and cell-to-cell transport.
Several recent studies have uncovered another level of control mechanism by linking the role of different carrier proteins in auxin homeostasis.