Plants adjust their growth according to gravity. Gravitropism involves gravity perception, signal transduction, and asymmetric growth response, with organ bending as a consequence [1]. Asymmetric growth results from the asymmetric distribution of the plant-specific signaling molecule auxin [2] that is generated by lateral transport, mediated in the hypocotyl predominantly by the auxin transport...

AUXIN RESPONSE FACTOR7 (ARF7) is one of five ARF transcriptional activators in Arabidopsis thaliana that is proposed to regulate auxin-responsive expression of genes containing TGTCTC auxin response elements in their promoters. An Arabidopsis mutant (nonphototropic hypocotyl4-1[nph4-1]) that is a null for ARF7 showed strongly reduced expression of integrated auxin-responsive reporter genes and ...

Auxin signaling is central to plant growth and development, yet hardly anything is known about its evolutionary origin. While the presence of key players in auxin signaling has been analyzed in various land plant species, similar analyses in the green algal lineages are lacking. Here, we survey the key players in auxin biology in the available genomes of Chlorophyta species. We found that the g...

Acid-induced growth was compared to auxin-induced growth. After a transient pH 4-induced increase in the elongation rate was completed, auxin could still induce an enhanced rate of elongation in soybean (Glycine max) hypocotyl segments. This auxin response occurred both when the medium was changed to pH 6 before auxin addition, and when the auxin was added directly to the pH 4 medium. This post...

The regular arrangement of leaves and flowers around a plant's stem is a fascinating expression of biological pattern formation. Based on current models, the spacing of lateral shoot organs is determined by transient local auxin maxima generated by polar auxin transport, with existing primordia draining auxin from their vicinity to restrict organ formation close by. It is unclear whether this m...

The phytohormone auxin is a major regulator of diverse aspects of plant growth and development. The ubiquitin-ligase complex SCF (for Skp1-Cul1-F-box protein), which includes the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX (TIR1/AFB) auxin receptor family, has recently been demonstrated to be critical for auxin-mediated transcriptional regulation. Early-phase auxin-induced hypocotyl elo...

The phytohormone auxin is a major regulator of diverse aspects of plant growth and development. The ubiquitin-ligase complex SCF(TIR1/AFB) (for Skp1-Cul1-F-box protein), which includes the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX (TIR1/AFB) auxin receptor family, has recently been demonstrated to be critical for auxin-mediated transcriptional regulation. Early-phase auxin-induced hyp...

Time course studies indicate that auxin prevents senescence of excised bean endocarp (Phaseolus zvlgaaris, L.. var. Kentucky Wonder pole beans) through an effect on metabolism of RNA. Firstly, during aging of tissue sections in absence of auxin degradation of RNA precedes degradation of DNA and protein: these degradations are prevented by auxin (4, 5, /7).. Secondly, during short (2-hr) incubat...

Arabidopsis thaliana S-Phase Kinase-Associated Protein 2A (SKP2A) is an F-box protein that regulates the proteolysis of cell cycle transcription factors. The plant hormone auxin regulates multiple aspects of plant growth and development, including cell division. We found that auxin induces the ubiquitin-dependent degradation of SKP2A both in vivo and in vitro, suggesting that this hormone acts ...

Postembryonic de novo organogenesis represents an important competence evolved in plants that allows their physiological and developmental adaptation to changing environmental conditions. The phytohormones auxin and cytokinin (CK) are important regulators of the developmental fate of pluripotent plant cells. However, the molecular nature of their interaction(s) in control of plant organogenesis...