Intracellular Auxin Transport

Abstract

The phytohormone auxin is of fundamental importance in plant development. Since the identification of auxin as a plant growth substance, auxin transport has drawn considerable research attention. Intercellular (polar) auxin transport contributes to its graded distribution in cell files or entire organs and allows for dynamic, environmentally controlled rearrangements in auxin accumulation. Insights into polar auxin transport mechanisms have broadened our understanding of the phenotypic flexibility of plants. Besides intercellular auxin transport, auxin is also transported intracellularly across organelle membranes, but its importance in plant development remains nascent. The intracellular sequestration of auxin into cellular compartments, such as peroxisomes and the endoplasmic reticulum (ER), plays important roles in auxin metabolism and could furthermore, in the case of the ER, have a direct impact on auxin signaling events. In this chapter, we review the most recent insights into intracellular auxin transport and its role in cellular auxin homeostasis.