The plant hormone auxin has been implicated in virtually every aspect of plant growth and development. Auxin acts by promoting the degradation of transcriptional regulators called Aux/IAA proteins. Aux/IAA degradation requires TIR1, an F box protein that has been shown to function as an auxin receptor. However, loss of TIR1 has a modest effect on auxin response and plant development. Here we sh...

Previous data have suggested an involvement of MDR/PGP-like ABC transporters in transport of the plant hormone auxin and, recently, AtPGP1 has been demonstrated to catalyze the primary active export of auxin. Here we show that related isoform AtPGP4 is expressed predominantly during early root development. AtPGP4 loss-of-function plants reveal enhanced lateral root initiation and root hair leng...

The plant hormone auxin, in particular indole-3-acetic acid (IAA), is a key regulator of virtually every aspect of plant growth and development. Auxin regulates transcription by rapidly modulating levels of Aux/IAA proteins throughout development. Recent studies demonstrate that auxin perception occurs through a novel mechanism. Auxin binds to TIR1, the F-box subunit of the ubiquitin ligase com...

Regulated auxin patterning provides a key mechanism for controlling root growth and development. We have developed a data-driven mechanistic model using realistic root geometry and formulated a principle to theoretically investigate quantitative auxin pattern recovery following auxin transport perturbation. This principle reveals that auxin patterning is potentially controlled by multiple combi...

The development and morphology of vascular plants is critically determined by synthesis and proper distribution of the phytohormone auxin. The directed cell-to-cell distribution of auxin is achieved through a system of auxin influx and efflux transporters. PIN-FORMED (PIN) proteins are proposed auxin efflux transporters, and auxin fluxes can seemingly be predicted based on the--in many cells--a...

Auxin signaling relies on ubiquitin ligase SCF(TIR1)-mediated 26S proteasome-dependent proteolysis of a large family of short-lived transcription regulators, auxin/indole acetic acid (Aux/IAA), resulting in the derepression of auxin-responsive genes. We have shown previously that a subset of Rac GTPases is activated by auxin, and they in turn stimulate auxin-responsive gene expression. We show ...

As a prominent regulator of plant growth and development, the hormone auxin plays an essential role in controlling cell division and expansion. Auxin-responsive gene transcription is mediated through the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX (TIR1/AFB) pathway. Roles for TIR1/AFB pathway components in auxin response are understood best, but additional factors implicated in auxin r...

Recent years have seen rapid progress in our understanding of the mechanism of action of the plant hormone auxin. A major emerging theme is the central importance of the interplay between auxin signalling and the active transport of auxin through the plant to create dynamic patterns of auxin accumulation. Even in tissues where auxin distribution patterns appear stable, they are the product of s...

The plant hormone auxin (indole-3-acetic acid) has been shown to regulate a wide variety of plant processes, including tropisms, vascular development and formation of lateral shoots and roots (for reviews see Aloni, 1995; Malamy and Benfey, 1997; Chen et al., 1999). At the cellular level, auxin affects elongation, division and differentiation, but the mechanisms by which it produces these cellu...

The plant hormone auxin (or IAA) plays a key role in a wide variety of growth and developmental processes. At the cellular level, auxin acts as a signal for division, extension, and differentiation during the course of the plant life cycle. At the whole-plant level, auxin plays an important role in root formation, apical dominance, tropism, and senescence. The question is how does such a simple...