Auxin activity: Past, present, and future

Enders, Tara A.; Strader, Lucia C.

doi:10.3732/ajb.1400285

Cited by 285 publications

(239 citation statements)

References 158 publications

(207 reference statements)

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“…A major challenge for auxin biologists is to explain how a small molecule such as IAA can trigger the vast range of intricate, complex, and tissue-specific responses throughout plant development (Paciorek and Friml, 2006;Teale et al, 2006;Benjamins and Scheres, 2008;Vanneste and Friml, 2009;Rademacher et al, 2012;Enders and Strader, 2015;Hagen, 2015). We have recently shown that the atypical auxin response factor ETT responds to changes in cellular auxin levels in a different way from the canonical TIR1-dependent auxin-signaling pathway (Simonini et al, 2016), thus providing an additional route for auxin to mediate its diverse effects.…”

Section: Discussionmentioning

confidence: 99%

Auxin-Induced Modulation of ETTIN Activity Orchestrates Gene Expression in Arabidopsis

et al. 2017

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The phytohormone auxin governs crucial developmental decisions throughout the plant life cycle. Auxin signaling is effectuated by auxin response factors (ARFs) whose activity is repressed by Aux/IAA proteins under low auxin levels, but relieved from repression when cellular auxin concentrations increase. ARF3/ETTIN (ETT) is a conserved noncanonical Arabidopsis thaliana ARF that adopts an alternative auxin-sensing mode of translating auxin levels into multiple transcriptional outcomes. However, a mechanistic model for how this auxin-dependent modulation of ETT activity regulates gene expression has not yet been elucidated. Here, we take a genome-wide approach to show how ETT controls developmental processes in the Arabidopsis shoot through its auxin-sensing property. Moreover, analysis of direct ETT targets suggests that ETT functions as a central node in coordinating auxin dynamics and plant development and reveals tight feedback regulation at both the transcriptional and protein-interaction levels. Finally, we present an example to demonstrate how auxin sensitivity of ETT-protein interactions can shape the composition of downstream transcriptomes to ensure specific developmental outcomes. These results show that direct effects of auxin on protein factors, such as ETT-TF complexes, comprise an important part of auxin biology and likely contribute to the vast number of biological processes affected by this simple molecule.

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Section: Discussionmentioning

confidence: 99%

Auxin-Induced Modulation of ETTIN Activity Orchestrates Gene Expression in Arabidopsis

et al. 2017

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“…The cell cohesion was characteristic for a callus with stable growth [37]. Moreover, the grey pigmentation present for all calli at 1.0 mg dm −3 2,4-D concentration may result from distinct cell hydration that is one of the characteristic effects of auxin action [38]; this is favorable for callus proliferation [39].…”

Section: Discussionmentioning

confidence: 99%

Changes accompanying proliferative capacity and morphology of Nicotiana tabacum L. callus in response to 2,4-D

2017

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The common trait of all auxins is a stimulation of cell elongation and also cell division in the presence of cytokinin; both are essential for callus induction and its multiplication. The response of plant tissues to various compounds with auxin activity may be quite different. In this study, the effectiveness of a synthetic auxin, 2,4-dichlorofenoxyacetic acid (2,4-D), instead of the generally applied natural auxin, indole-3-acetic acid (IAA), was tested for the proliferation of Nicotiana tabacum callus. The following concentrations of 2,4-D were tested: 0.1, 0.5, 1.0, 1.5, and 2.0 mg dm −3 . Callus was derived from stem pith and its proliferation allowed on MS medium through five subcultures at 25°C and in darkness. After each passage, the fresh weight and morphological features of the callus were determined. The 0.5 mg dm −3 2,4-D treatment was the most favorable for producing the greatest increase in fresh weight in each of five subsequent subcultures as well as maintaining normal morphological features for proliferation. However, the 1.0 mg dm −3 2,4-D treatment in comparison with the lowest, 0.1 mg dm −3 , was more beneficial when considering regular increases of fresh weight and a better cell cohesion for callus growth.

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“…Auxin regulates a wide range of developmental processes, and tight control of auxin response is maintained by multiple modes of regulation. These include regulating auxin biosynthesis and metabolism, transport, and signaling (reviewed in Enders and Strader, 2015). To date, nuclear auxin signaling components have been well characterized (reviewed in Chapman and Estelle, 2009;Salehin et al, 2015).…”

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confidence: 99%

Genome Sequencing of Arabidopsis abp1-5 Reveals Second-Site Mutations That May Affect Phenotypes

Enders

Yang

et al. 2015

The Plant Cell

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Auxin regulates numerous aspects of plant growth and development. For many years, investigating roles for AUXIN BINDING PROTEIN1 (ABP1) in auxin response was impeded by the reported embryo lethality of mutants defective in ABP1. However, identification of a viable Arabidopsis thaliana TILLING mutant defective in the ABP1 auxin binding pocket (abp1-5) allowed inroads into understanding ABP1 function. During our own studies with abp1-5, we observed growth phenotypes segregating independently of the ABP1 lesion, leading us to sequence the genome of the abp1-5 line described previously. We found that the abp1-5 line we sequenced contains over 8000 single nucleotide polymorphisms in addition to the ABP1 mutation and that at least some of these mutations may originate from the Arabidopsis Wassilewskija accession. Furthermore, a phyB null allele in the abp1-5 background is likely causative for the long hypocotyl phenotype previously attributed to disrupted ABP1 function. Our findings complicate the interpretation of abp1-5 phenotypes for which no complementation test was conducted. Our findings on abp1-5 also provide a cautionary tale illustrating the need to use multiple alleles or complementation lines when attributing roles to a gene product. INTRODUCTIONThe plant hormone auxin regulates cell division and cell expansion to affect all aspects of plant growth (reviewed in PerrotRechenmann, 2010). Auxin regulates a wide range of developmental processes, and tight control of auxin response is maintained by multiple modes of regulation. These include regulating auxin biosynthesis and metabolism, transport, and signaling (reviewed in Enders and Strader, 2015). To date, nuclear auxin signaling components have been well characterized (reviewed in Chapman and Estelle, 2009;Salehin et al., 2015). In addition, a nontranscriptional auxin response pathway has been proposed, with AUXIN BINDING PROTEIN1 (ABP1) acting in the apoplast as an auxin receptor and transmitting a cytoplasmic signal to regulate auxin responses such as auxin transport and cytoskeletal rearrangements (reviewed in Shi and Yang, 2011;Sauer et al., 2013).Study of ABP1 has a long, complicated history. Experiments demonstrating auxin binding activity for ABP1 were published as early as the 1980s (reviewed in Jones, 1994). Reverse genetics proved to be a complicated approach to study ABP1 function in Arabidopsis thaliana, as two independently generated abp1 mutants, presumed to be null alleles, appeared to be embryo lethal (Chen et al., 2001;Tzafrir et al., 2004;Meinke et al., 2008;Sassi et al., 2014). Knockdown lines of ABP1 provided some ability to study ABP1 function by reverse genetics. Arabidopsis lines expressing an inducible ABP1 antisense transcript or an inducible single-chain fragment variable scFv12 (David et al., 2007) from a monoclonal antibody raised to ABP1 (Leblanc et al., 1999), targeted to either the apoplast (SS12S) or the endoplasmic reticulum (SS12K), led to phenotypes consistent with decreased auxin activity (Braun et al., 2008;Tromas et al.,...

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Auxin activity: Past, present, and future

Cited by 285 publications

References 158 publications

Auxin-Induced Modulation of ETTIN Activity Orchestrates Gene Expression in Arabidopsis

Auxin-Induced Modulation of ETTIN Activity Orchestrates Gene Expression in Arabidopsis

Changes accompanying proliferative capacity and morphology of Nicotiana tabacum L. callus in response to 2,4-D

Genome Sequencing of Arabidopsis abp1-5 Reveals Second-Site Mutations That May Affect Phenotypes

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