Molecular Cloning and Expression of The Early Auxin-Responsive Aux/IAA Gene Family in Nicotiana tabacum

Dargeviciute, Ausra; Roux, Camille; Decreux, Annabelle; Sitbon, Folke; Perrot‐Rechenmann, Catherine

doi:10.1093/oxfordjournals.pcp.a029311

Cited by 47 publications

(41 citation statements)

References 35 publications

(47 reference statements)

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“…The strong sequence similarity of the highly conserved Aux/IAA domains I to IV, the nuclear localization of the encoded protein, and the phenotypes of the AS-IAA9 tomato lines strongly suggest that IAA9 encodes a functional Aux/IAA protein. Aux/IAA multigene families have been isolated from Arabidopsis (Abel et al, 1995), tobacco (Dargeviciute et al, 1998), tomato (Nebenfuhr et al, 2000), soybean (Glycine max; Ainley et al, 1988), and a number of other dicot and monocot species. Tomato IAA9 and its putative Arabidopsis orthologs, IAA9 and IAA8, belong to Aux/IAA subfamily IV (Figure 2), which includes members encoding proteins 50 to 89% larger than Aux/ IAAs from all other subfamilies.…”

Section: Discussionmentioning

confidence: 99%

The TomatoAux/IAATranscription FactorIAA9Is Involved in Fruit Development and Leaf Morphogenesis

et al. 2005

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Auxin/indole-3-acetic acid (Aux/IAA) proteins are transcriptional regulators that mediate many aspects of plant responses to auxin. While functions of most Aux/IAAs have been defined mainly by gain-of-function mutant alleles in Arabidopsis thaliana, phenotypes associated with loss-of-function mutations have been scarce and subtle. We report here that the downregulation of IAA9, a tomato (Solanum lycopersicum) gene from a distinct subfamily of Aux/IAA genes, results in a pleiotropic phenotype, consistent with its ubiquitous expression pattern. IAA9-inhibited lines have simple leaves instead of wild-type compound leaves, and fruit development is triggered before fertilization, giving rise to parthenocarpy. This indicates that IAA9 is a key mediator of leaf morphogenesis and fruit set. In addition, antisense plants displayed auxin-related growth alterations, including enhanced hypocotyl/stem elongation, increased leaf vascularization, and reduced apical dominance. Auxin dose-response assays revealed that IAA9 downregulated lines were hypersensitive to auxin, although the only early auxin-responsive gene that was found to be upregulated in the antisense lines was IAA3. The activity of the IAA3 promoter was stimulated in the IAA9 antisense genetic background, indicating that IAA9 acts in planta as a transcriptional repressor of auxin signaling. While no mutation in any member of subfamily IV has been reported to date, the phenotypes associated with the downregulation of IAA9 reveal distinct and novel roles for members of the Aux/IAA gene family. INTRODUCTIONThe phytohormone auxin is central to a myriad of aspects of plant growth and developmental processes. At the cellular level, auxin controls cell division, extension, and differentiation. On a wholeplant level, auxin plays an essential role in processes such as apical dominance, lateral/adventitious root formation, tropisms, fruit set and development, vascular differentiation, and embryogenesis (Friml, 2003). While it is clear that auxin plays a pivotal role in plant growth and development, the molecular effectors by which this hormone exerts its effect are still relatively unknown. For example, in the process of fruit set, the onset of ovary development into fruit and its subsequent development are naturally triggered by signals from successful fertilization. These processes can be initiated in the absence of pollination and fertilization by exogenous auxin or auxin transport inhibitors (Gustafson, 1937;Beyer and Quebedeaux, 1974) or by the ovaryspecific expression of Agrobacterium tumefaciens indoleacetamide monoxygenase (iaaM) or root loci B (rolB) genes, which confer higher auxin production or increased auxin sensitivity, respectively (Ficcadenti et al., 1999;Carmi et al., 2003). The molecular mediators by which auxin impacts this process are still unknown.The recent discovery that the F-box protein Transport Inhibitor Response1 functions as an auxin receptor represents a major breakthrough (Dharmasiri et al., 2005;Kepinski and Leyser, 2005) in understanding ho...

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Section: Discussionmentioning

confidence: 99%

The TomatoAux/IAATranscription FactorIAA9Is Involved in Fruit Development and Leaf Morphogenesis

et al. 2005

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“…These herbicidal auxins exhibit a broad range of potencies and differential selectivities to various plant species (Sterling and Hall, 1997). Despite their structural differences, many studies have shown that these synthetic auxins induce similar morphological, physiological, and molecular events (Chang and Foy, 1983;Boerjan et al, 1992;Grossmann et al, 1996;Dargeviciute et al, 1998;Pufky et al, 2003). However, it is presently unclear whether these structurally different auxinic compounds act via the same mechanisms and signal transduction components that have been characterized for 2,4-D and IAA.…”

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confidence: 99%

“…We have screened for Arabidopsis mutations that confer differential resistance to 2,4-D and picolinate auxins using a novel picolinate auxin as an initial probe. We reasoned that if IAA, 2,4-D, and picolinate auxinic compounds all promote common downstream events, as suggested by the similar physiological and morphological responses to the compounds (Chang and Foy, 1983;Boerjan et al, 1992;Grossmann et al, 1996;Dargeviciute et al, 1998;Pufky et al, 2003), then identification of mutants that are selectively resistant to picolinate chemistries could preferentially identify mutations involved in upstream events close to or at the site of chemical interaction. Using this strategy, we have succeeded in isolating and characterizing several mutant alleles at two genetic loci that confer selective resistance to the picolinate class of herbicidal auxins.…”

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Mutations in an Auxin Receptor Homolog AFB5 and in SGT1b Confer Resistance to Synthetic Picolinate Auxins and Not to 2,4-Dichlorophenoxyacetic Acid or Indole-3-Acetic Acid in Arabidopsis

et al. 2006

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Although a wide range of structurally diverse small molecules can act as auxins, it is unclear whether all of these compounds act via the same mechanisms that have been characterized for 2,4-dichlorophenoxyacetic acid (2,4-D) and indole-3-acetic acid (IAA). To address this question, we used a novel member of the picolinate class of synthetic auxins that is structurally distinct from 2,4-D to screen for Arabidopsis (Arabidopsis thaliana) mutants that show chemically selective auxin resistance. We identified seven alleles at two distinct genetic loci that conferred significant resistance to picolinate auxins such as picloram, yet had minimal cross-resistance to 2,4-D or IAA. Double mutants had the same level and selectivity of resistance as single mutants. The sites of the mutations were identified by positional mapping as At4g11260 and At5g49980. At5g49980 is previously uncharacterized and encodes auxin signaling F-box protein 5, one of five homologs of TIR1 in the Arabidopsis genome. TIR1 is the recognition component of the Skp1-cullin-F-box complex associated with the ubiquitin-proteasome pathway involved in auxin signaling and has recently been shown to be a receptor for IAA and 2,4-D. At4g11260 encodes the tetratricopeptide protein SGT1b that has also been associated with Skp1-cullin-F-box-mediated ubiquitination in auxin signaling and other pathways. Complementation of mutant lines with their corresponding wild-type genes restored picolinate auxin sensitivity. These results show that chemical specificity in auxin signaling can be conferred by upstream components of the auxin response pathway. They also demonstrate the utility of genetic screens using structurally diverse chemistries to uncover novel pathway components.

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“…Then, a series of experiments to test LaIAA2 gene expression patterns were done. In the test of timing of LaIAA2 expression, LaIAA2 mRNA reached maximal levels at 1 day after treatment; this differed from Aux/IAA genes in tobacco seedlings, which declined to near basal levels within 24 h of NAA treatment (Dargeviciute et al, 1998). The persistence of elevated mRNA levels of the LaIAA2 could be the result of the continued presence of NAA in its active form in Larix cuttings.…”

Section: Discussionmentioning

confidence: 90%

Isolation and characterization of an Aux/IAA gene (LaIAA2) from Larix

Feng¹,

Liu²,

Sun³

et al. 2012

Afr. J. Biotechnol.

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Molecular Cloning and Expression of The Early Auxin-Responsive Aux/IAA Gene Family in Nicotiana tabacum

Cited by 47 publications

References 35 publications

The TomatoAux/IAATranscription FactorIAA9Is Involved in Fruit Development and Leaf Morphogenesis

The TomatoAux/IAATranscription FactorIAA9Is Involved in Fruit Development and Leaf Morphogenesis

Mutations in an Auxin Receptor Homolog AFB5 and in SGT1b Confer Resistance to Synthetic Picolinate Auxins and Not to 2,4-Dichlorophenoxyacetic Acid or Indole-3-Acetic Acid in Arabidopsis

Isolation and characterization of an Aux/IAA gene (LaIAA2) from Larix

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