Rapid degradation of auxin/indoleacetic acid proteins requires conserved amino acids of domain II and is proteasome dependent. Auxin regulates SCF TIR1-dependent degradation of AUX/IAA proteins. Degradation of Aux/IAA proteins is essential for normal auxin signalling. Mutations in the AXR3 gene of Arabidopsis result in altered auxin response including ectopic expression from the SAUR-AC1 promoter. IAA17/AXR3: biochemical insight into an auxin mutant phenotype. ARF1, a transcription factor that binds to auxin response elements. Activation and repression of transription by auxin-response factors. Identification of the auxin-responsive element, AuxRE, in the primary indoleacetic acid-inducible gene, PS-IAA4/5, of pea ( Pisum sativum). This paper shows that overexpression of Aux/IAA proteins results in the specific repression of the DR5 reporter gene.īallas, N., Wong, L. The authors created a highly active synthetic ARE (known as DR5) that has become the standard tool for studying auxin-responsive transcription. Aux/IAA proteins repress expression of reporter genes containing natural and highly active synthetic auxin responsive elements. Overlapping functions of the yeast oxysterol-binding protein homologues. Functional genomic analysis of the AUXIN/INDOLE-3-ACETIC ACID gene family members in Arabidopsis thaliana. Functional genomic analysis of the AUXIN RESPONSE FACTOR gene family members in Arabidopsis thaliana: unique and overlapping functions of ARF7 and ARF19. Contrasting modes of diversification in the Aux/IAA and ARF gene families. Rapid induction of selective transcription by auxins. Characterisation of a class of small auxin-inducible soybean polyadenylated RNAs. The ubiquitin-related protein RUB1 and auxin response in Arabidopsis. Function of the ubiquitin–proteosome pathway in auxin response. Arabidopsis auxin-resistance gene AXR1 encodes a protein related to ubiquitin-activating enzyme E1. RNA and protein biosynthesis and the regulation of cell elongation by auxin.

Rapid induction of specific mRNAs by auxin in pea epicotyl tissue. Early auxin-regulated polyadenylylated mRNA sequences in pea stem tissue. Enhancing the efficacy of photodynamic cancer therapy by radicals from plant auxin (indole-3-acetic acid). Oxidative activation of indole-3-acetic acids to cytotoxic species - a potential new role for plant auxins in cancer therapy. On growth accelerating substances in the coleoptile of Avena sativa. Beiträge zur Analyse der geotropischen Reaktion. The Power of Movement in Plants (John Murray, London, 1880).Ĭholodny, N. Vorlesungen über Pflanzenphysiologie (Engelmann, Leipzig, 1887) (in German).ĭarwin, F. The involvement of an increasing number of proteins that were previously considered as components of signalling networks that are also involved in auxin transport is currently opening a new chapter in auxin biology. This transport is mediated by several transporters and signalling events that are separate from ARE-mediated gene transcription.Īlthough not traditionally considered together, it is becoming increasingly clear that auxin signalling and auxin transport are linked. The phytohormone that best fits the classical definition of a hormone is auxin as it is transported between its site of synthesis and site of action. These other pathways are likely to be extremely rapid, and certain auxin responses are seen almost instantaneously. Other auxin-binding proteins such as AUXIN-BINDING PROTEIN-1 (ABP1) also confer auxin sensitivity and might also represent auxin receptors. These F-box proteins probably do not represent the only mechanism of auxin perception. TIR1 is one of a family of four similar F-box-domain-containing proteins, which all mediate an auxin response and represent the first confirmed auxin receptors. The association between TIR1 and Aux/IAAs is enhanced by the direct binding of auxin to TIR1. Aux/IAAs are marked for proteolysis by the action of the SCF TIR1 E3 ubiquitin ligase. ARE-mediated transcription is inhibited by the binding of Aux/IAA proteins to ARFs.Īuxin functions by stimulating the ubiquitin-mediated proteolysis of Aux/IAAs. ARE-mediated transcription is initiated through the action of auxin response factors (ARFs) to AREs. The most well-characterized auxin signalling events are mediated by auxin-responsive elements (AREs) in the promoters of auxin primary-response genes. Auxins have profound effects on many aspects of plant development - they affect cell division, elongation and differentiation - but their modes of action are complicated.

Auxins form a class of small indolic plant growth regulators that was initially identified as the motile stimulus that causes plants to bend towards the light.

Signal transduction pathway examples