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Hagen, Gretchen; Guilfoyle, Tom J.

doi:10.1023/a:1015207114117

Cited by 1,016 publications

(366 citation statements)

References 72 publications

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“…An increase in free auxin in the flank distal to the incident tropic stimulation is then believed to promote the degradation of MSG2͞IAA19 (13,25) via a ubiquitination and proteasome-dependent process (36), allowing for homodimerization of NPH4͞ARF7 (13,25) and subsequent transcriptional activation of target genes, including MSG2͞IAA19 (13,21) and GH3.6͞DFL1 (18). Newly translated MSG2͞IAA19 would then compete with NPH4͞ARF7 monomers for dimerization with DNA-bound NPH4͞ARF7 (21,25) to rerepress the system, whereas synthesis of amido-IAA conjugates by GH3.6͞DFL1 (33) would be predicted to reduce free IAA levels and thus further strengthen repression of NPH4͞ARF7 activity by reducing auxin-dependent (37, 38) turnover of MSG2͞IAA19. The coordinate regulation of GH3.5 and GH3.6͞DFL1 transcript abundance in response to tropic stimulation (Fig.…”

Section: Discussionmentioning

confidence: 99%

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A gradient of auxin and auxin-dependent transcription precedes tropic growth responses

Esmon

Tinsley

Ljung

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

209

210

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Yet the molecular identities of such output components, which are likely to encode proteins directly involved in growth control, have remained elusive. Here we report the discovery of a suite of tropic stimulus-induced genes in Brassica oleracea that are responsive to an auxin gradient and exhibit morphologically graded expression concomitant with, or before, observable curvature responses. These results provide compelling molecular support for the Cholodny-Went theory and suggest that morphologically graded transcription represents an important mechanism for interpreting tropically stimulated gradients of auxin. Intriguingly, two of the tropic stimulus-induced genes, EXPA1 and EXPA8, encode enzymes involved in cell wall extension, a response prerequisite for differential growth leading to curvatures, and are up-regulated before curvature in the flank that will elongate. This observation suggests that morphologically graded transcription likely leads to the graded expression of proteins whose activities can directly regulate the establishment and modulation of tropic curvatures.gravitropism ͉ NPH4͞ARF7 ͉ phototropism

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Section: Discussionmentioning

confidence: 99%

“…1C) is not sufficient to stimulate expression of all auxin-responsive genes. For example, At2g23170͞GH3.3 (21) and AT4G14550͞SLR͞IAA14 (25), although expressed in B. oleracea hypocotyls segments, did not exhibit differential expression in response to tropic stimulation (Fig. 3).…”

Section: Tsi Transcript Accumulation Depends Upon Auxin and Occurs Comentioning

confidence: 95%

A gradient of auxin and auxin-dependent transcription precedes tropic growth responses

Esmon

Tinsley

Ljung

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

209

210

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“…Meanwhile SAURs have been identified in a variety of organisms, in Vigna radiata (7), Pisum sativum (8), Arabidopsis thaliana (9), Nicotiana tabacum (10), Raphanus sativus (11), Malus domestica (12) and more recently also in Zea mays (13). Genome analysis in A. thaliana reveals more than 70 SAUR homologs, which mostly are found in clusters (3). However, it is not known how many of them are really expressed and are auxin-inducible.…”

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confidence: 99%

The Auxin-induced Maize Gene ZmSAUR2 Encodes a Short-lived Nuclear Protein Expressed in Elongating Tissues

Knauss

Rohrmeier

Lehle

2003

Journal of Biological Chemistry

104

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By differential screening of a cDNA library from auxin-induced maize coleoptiles we have isolated and characterized a SAUR gene, designated ZmSAUR2, belonging to a not yet characterized subtype of the SAUR family. ZmSAUR2 encodes a 15.3-kDa protein and is specifically induced by auxin in elongating coleoptile tissue but not in primary leaves or in roots. The transcript level rapidly increased within minutes and preceded auxin-stimulated elongation of coleoptile segments. Cycloheximide also induced ZmSAUR2 transcription, as has been shown for other early auxin-induced genes, whereas abscisic acid, brassinolide, ethylene, gibberellic acid, kinetin, and methyl jasmonate did not provoke an increase in ZmSAUR2 mRNA abundance. In pulse-chase experiments using auxin-induced coleoptiles and an anti-Zm-SAUR2 antibody we were able to precipitate a protein of the expected molecular mass and to determine a half-life of about 7 min, which is among the shortest known in eukaryotes. In gel shift assays binding of calmodulin to ZmSAUR2 was demonstrated, suggesting the possibility of post-transcriptional regulation. Upon transformation of onion epidermal cells with a ZmSAUR2::GUS construct the corresponding chimeric protein was detected in the nucleus. The results suggest that ZmSAUR2 encodes a short-lived nuclear protein that might be involved in auxin-mediated cell elongation.

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“…Consistent with the diverse effects of auxin on growth and development is that the expression patterns of a number of genes are dramatically and rapidly altered by auxin application (2), suggesting that auxin ultimately regulates cell growth by controlling the profile of expressed genes. AUX/IAA genes comprise a 34-member gene family in Arabidopsis that is one of three known gene families that are regulated by auxin and implicated to play essential roles in auxin signaling (3,4).…”

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confidence: 99%

Yokonolide B, a Novel Inhibitor of Auxin Action, Blocks Degradation of AUX/IAA Factors

Hayashi

Jones

Ogino

et al. 2003

Journal of Biological Chemistry

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Yokonolide B (YkB; also known as A82548A), a spiroketal-macrolide, was isolated from Streptomyces diastatochromogenes B59 in a screen for inhibitors of ␤-glucoronidase expression under the control of an auxin-responsive promoter in Arabidopsis. YkB inhibits the expression of auxin-inducible genes as shown using native and synthetic auxin promoters as well as using expression profiling of 8,300 Arabidopsis gene probes but does not affect expression of an abscisic acid-and a gibberellin A 3 -inducible gene. The mechanism of action of YkB is to block AUX/IAA protein degradation; however, YkB is not a general proteasome inhibitor. YkB blocks auxin-dependent cell division and auxin-regulated epinastic growth mediated by auxin-binding protein 1. Gain of function mutants such as shy2-2, slr1, and axr2-1 encoding AUX/IAA transcriptional repressors and loss of function mutants encoding components of the ubiquitin-proteolytic pathway such as axr1-3 and tir1-1, which display increased AUX/IAAs protein stability, are less sensitive to YkB, although axr1 and tir1 mutants were sensitive to MG132, a general proteasome inhibitor, consistent with a site of action downstream of AXR1 and TIR. YkB-treated seedlings displayed similar phenotypes as dominant AUX/IAA mutants. Taken together, these results indicate that YkB acts to block AUX/IAA protein degradation upstream of AXR and TIR, links a shared element upstream of AUX/IAA protein stability to auxin-induced cell division/elongation and to auxin-binding protein 1, and provides a new tool to dissect auxin signal transduction.Auxin controls cell division, elongation, and differentiation and therefore, through its action at the level of the cell, exerts profound effects on growth and development throughout the life of the plant (1). Consistent with the diverse effects of auxin on growth and development is that the expression patterns of a number of genes are dramatically and rapidly altered by auxin application (2), suggesting that auxin ultimately regulates cell growth by controlling the profile of expressed genes. AUX/IAA genes comprise a 34-member gene family in Arabidopsis that is one of three known gene families that are regulated by auxin and implicated to play essential roles in auxin signaling (3, 4).The molecular and genetic studies on auxin signaling have revealed that auxin specifically enhances the transcription of many AUX/IAA genes within minutes without requiring de novo protein synthesis, suggesting that AUX/IAA genes are primary auxin-response genes (5, 6). AUX/IAA genes encode short lived nuclear proteins capable of heterodimerization with auxin-responsive factors (7) and are thought to act by negatively regulating the expression of early auxin-responsive genes including other members of the AUX/IAA family (3).Studies on Arabidopsis mutants with altered responses to auxin such as iaa3/shy2-2, iaa7/axr2-1, iaa17/axr3, iaa14/slr1, tir1, and axr1 revealed that the turnover rate of AUX/IAA proteins is in some way important in various developmental processes including ...

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Cited by 1,016 publications

References 72 publications

A gradient of auxin and auxin-dependent transcription precedes tropic growth responses

A gradient of auxin and auxin-dependent transcription precedes tropic growth responses

The Auxin-induced Maize Gene ZmSAUR2 Encodes a Short-lived Nuclear Protein Expressed in Elongating Tissues

Yokonolide B, a Novel Inhibitor of Auxin Action, Blocks Degradation of AUX/IAA Factors

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