Characterization of a Family of IAA-Amino Acid Conjugate Hydrolases from Arabidopsis

LeClere, Sherry; Tellez, Rosie; Rampey, Rebekah A.; Matsuda, Seiichi P. T.; Bartel, Bonnie

doi:10.1074/jbc.m111955200

Cited by 275 publications

(307 citation statements)

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“…[See online article for color version of this figure. ] hydrolase (Davies et al, 1999); and ILL2, an IAA-Ala hydrolase (LeClere et al, 2002). We found that the ilr1-1 iar3-2 ill2-1 triple mutant root hairs were approximately 30% shorter than wild type (Fig.…”

Section: Defects In Iaa Conjugate Hydrolases Results In Shortened Rootmentioning

confidence: 74%

“…Mutation of Arabidopsis (Arabidopsis thaliana) genes encoding IAA-amino acid hydrolases, including ILR1, IAR3, and ILL2, reduces plant sensitivity to the applied IAA-amino acid conjugates that are substrates of these enzymes, including IAA-Leu, IAA-Phe, and IAA-Ala (Bartel and Fink, 1995;Davies et al, 1999;LeClere et al, 2002;Rampey et al, 2004), which are present in Arabidopsis (Tam et al, 2000;Kowalczyk and Sandberg, 2001;Kai et al, 2007).…”

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confidence: 99%

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Conversion of Endogenous Indole-3-Butyric Acid to Indole-3-Acetic Acid Drives Cell Expansion in Arabidopsis Seedlings

et al. 2010

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Genetic evidence in Arabidopsis (Arabidopsis thaliana) suggests that the auxin precursor indole-3-butyric acid (IBA) is converted into active indole-3-acetic acid (IAA) by peroxisomal b-oxidation; however, direct evidence that Arabidopsis converts IBA to IAA is lacking, and the role of IBA-derived IAA is not well understood. In this work, we directly demonstrated that Arabidopsis seedlings convert IBA to IAA. Moreover, we found that several IBA-resistant, IAA-sensitive mutants were deficient in IBA-to-IAA conversion, including the indole-3-butyric acid response1 (ibr1) ibr3 ibr10 triple mutant, which is defective in three enzymes likely to be directly involved in peroxisomal IBA b-oxidation. In addition to IBA-to-IAA conversion defects, the ibr1 ibr3 ibr10 triple mutant displayed shorter root hairs and smaller cotyledons than wild type; these cell expansion defects are suggestive of low IAA levels in certain tissues. Consistent with this possibility, we could rescue the ibr1 ibr3 ibr10 shortroot-hair phenotype with exogenous auxin. A triple mutant defective in hydrolysis of IAA-amino acid conjugates, a second class of IAA precursor, displayed reduced hypocotyl elongation but normal cotyledon size and only slightly reduced root hair lengths. Our data suggest that IBA b-oxidation and IAA-amino acid conjugate hydrolysis provide auxin for partially distinct developmental processes and that IBA-derived IAA plays a major role in driving root hair and cotyledon cell expansion during seedling development.

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Section: Defects In Iaa Conjugate Hydrolases Results In Shortened Rootmentioning

confidence: 74%

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confidence: 99%

Conversion of Endogenous Indole-3-Butyric Acid to Indole-3-Acetic Acid Drives Cell Expansion in Arabidopsis Seedlings

et al. 2010

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“…1). Both the IAR3 and TaIAR3 products contain putative endoplasmic reticulum localization signals (data not shown), a hallmark of many of the auxin amidohydrolases (Davies et al, 1999;LeClere et al, 2002;Campanella et al, 2003aCampanella et al, , 2003c.…”

Section: Substrate Specificity Of Taiar3mentioning

confidence: 90%

“…This gene family was originally characterized in the model plant Arabidopsis (Bartel and Fink, 1995;Davies et al, 1999;LeClere et al, 2002). The ILL1, ILL2, and IAR3 enzymes cleave IAA-Ala preferentially, while ILR1 prefers IAA-Leu and IAA-Phe as substrates.…”

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A Novel Auxin Conjugate Hydrolase from Wheat with Substrate Specificity for Longer Side-Chain Auxin Amide Conjugates

et al. 2004

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This study investigates how the ILR1-like indole acetic acid (IAA) amidohydrolase family of genes has functionally evolved in the monocotyledonous species wheat (Triticum aestivum). An ortholog for the Arabidopsis IAR3 auxin amidohydrolase gene has been isolated from wheat (TaIAR3). The TaIAR3 protein hydrolyzes negligible levels of IAA-Ala and no other IAA amino acid conjugates tested, unlike its ortholog IAR3. Instead, TaIAR3 has low specificity for the ester conjugates IAA-Glc and IAAmyoinositol and high specificity for the conjugates of indole-3-butyric acid (IBA-Ala and IBA-Gly) and indole-3-propionic-acid (IPA-Ala) so far tested. TaIAR3 did not convert the methyl esters of the IBA conjugates with Ala and Gly. IBA and IBA conjugates were detected in wheat seedlings by gas chromatography-mass spectrometry, where the conjugate of IBA with Ala may serve as a natural substrate for this enzyme. Endogenous IPA and IPA conjugates were not detected in the seedlings. Additionally, crude protein extracts of wheat seedlings possess auxin amidohydrolase activity. Temporal expression studies of TaIAR3 indicate that the transcript is initially expressed at day 1 after germination. Expression decreases through days 2, 5, 10, 15, and 20. Spatial expression studies found similar levels of expression throughout all wheat tissues examined.In vascular plants, auxins, primarily indole-3-acetic acid (IAA), regulate gene expression, cell division, and cell elongation and differentiation in plant tissue. Auxins also affect vascularization, phototropism, geotropism, fruit development, flower development, and apical dominance (Davies, 1995). While IAA in low concentrations stimulates growth and development, higher concentrations can be toxic to the plant (Bandurski et al., 1995). Therefore, tight control of IAA concentration is necessary for proper plant development.IAA is stored in conjugated forms that are mostly considered to be inactive. Two main types of conjugated molecules have been studied: the amide-linked IAA forms bound to one or more amino acids and the ester-linked forms primarily bound to a sugar(s). These two types of conjugates appear to be found at varying concentrations in the diverse tissues of angiosperms (Domagalski et al., 1987). On average, 95% of all IAA in a plant is conjugated into these storage forms (Cohen and Bandurski, 1982;Bandurski et al., 1995;Campanella et al., 1996;Walz et al., 2002).There have been a variety of amide conjugates found in the plants studied to date. IAA-Asp has been identified as a natural conjugate in Scots pine (Pinus sylvestris; Andersson and Sandberg, 1982) and, together with IAA-Glu, in cucumber (Sonner and Purves, 1985) and soybean (Cohen, 1982). IAA-Ala has been detected in Picea abies Karst (Ö stin et al., 1992). Additionally, IAA-Ala, IAA-Asp, IAA-Leu, and IAA-Glu have been detected in Arabidopsis L. Heynh (Tam et al., 2000;Kowalczyk and Sandberg, 2001), although recent data suggest that IAA peptides may account for the majority of amide conjugates in this and other plant ...

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“…14 In contrast, formation of IAA-aspartate and IAA-glutamate marks auxin for subsequent metabolic degradation and conjugation of IAA with either alanine or leucine maintains a ready pool for formation of the active free acid form of auxin. 15,16 Thus, metabolism of IAA and JA provides a simple means of modulating plant hormone receptor occupancy and controlling gene responses. Some GH3 family of proteins catalyze the conjugations of various amino acids to plant hormones, including JA and IAA; however, Characterization of multiple group II GH3 genes in Arabidopsis also demonstrates critical roles in plant growth and development primarily through the conjugation of IAA to amino acids.…”

Section: Modulating Plant Hormones By Enzyme Actionmentioning

confidence: 99%

Modulating plant hormones by enzyme action

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Herrmann

Chen

et al. 2010

Plant Signaling & Behavior

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Characterization of a Family of IAA-Amino Acid Conjugate Hydrolases from Arabidopsis

Cited by 275 publications

References 46 publications

Conversion of Endogenous Indole-3-Butyric Acid to Indole-3-Acetic Acid Drives Cell Expansion in Arabidopsis Seedlings

Conversion of Endogenous Indole-3-Butyric Acid to Indole-3-Acetic Acid Drives Cell Expansion in Arabidopsis Seedlings

A Novel Auxin Conjugate Hydrolase from Wheat with Substrate Specificity for Longer Side-Chain Auxin Amide Conjugates

Modulating plant hormones by enzyme action

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