Identification of indole-3-butyric acid as an endogenous constituent of maize kernels and leaves

Epstein, Ephraim; Chen, Kai-Hsien; Cohen, Jerry D.

doi:10.1007/bf00025391

Cited by 48 publications

(25 citation statements)

References 13 publications

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“…1). The mass spectra ofthe purified and methylated pea extract is consistent with the mass spectra of the methyl ester of IBA obtained by Schneider et al (26) and Epstein et al (12). Highest concentrations of IBA were found in the shoot apex (35.5 ± 4.5 ng/g fresh weight).…”

Section: Gc-mssupporting

confidence: 88%

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Effect of Exogenous Indole-3-Acetic Acid and Indole-3-Butyric Acid on Internal Levels of the Respective Auxins and Their Conjugation with Aspartic Acid during Adventitious Root Formation in Pea Cuttings

Nordström

Jacobs²,

Eliasson³

1991

Plant Physiol.

161

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The influence of exogenous indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) on the internal levels of these auxins was studied during the first 4 days of adventitious root formation in cuttings of Pisum sativum L. The quantitations were done by high performance liquid chromatography with spectrofluorometric detection. IBA, identified by combined gas chromatography-mass spectrometry (GC-MS), was found to naturally occur in this plant material. The root inducing ability of exogenous IBA was superior to that of IAA. The IAA level in the tissue increased considerably on the first day after application of IAA, but rapidly decreased again, returning to a level twice the control by day 3. The predominant metabolic route was conjugation with aspartic acid, as reflected by the increase in the level of indole-3-acetylaspartic acid. The IBA treatment resulted in increases in the levels of IBA, IAA, and indole-3-acetylaspartic acid. The IAA content rapidly returned to control levels, whereas the IBA level remained high throughout the experimental period. High amounts of indole-3-butyrylaspartic acid were found in the tissue after feeding with IBA. The identity of the conjugate was confirmed by 'H-nuclear magnetic resonance and GC-MS. IBA was much more stable in solution than IAA. No IAA was detected after 48 hours, whereas 70% IBA was still recovered after this time. The relatively higher root inducing ability of IBA is ascribed to the fact that its level remained elevated longer than that of IAA, even though IBA was metabolized in the tissue. Adventitious root formation is discussed on the basis of these findings.Auxins and cytokinins appear to be the major endogenous factors regulating adventitious root formation. The cytokinins are considered inhibitory (6, 7), whereas the auxins are stimulatory (13, 21). Although IAA is probably the major auxin,

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Section: Gc-mssupporting

confidence: 88%

“…The cytokinins are considered inhibitory (6,7), whereas the auxins are stimulatory (13,21). Although IAA is probably the major auxin, the possibility that other naturally occurring ones like IBA, PAA, 4C1-IAA, and IPA (12,26) participate in regulation cannot be discounted.…”

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confidence: 99%

Effect of Exogenous Indole-3-Acetic Acid and Indole-3-Butyric Acid on Internal Levels of the Respective Auxins and Their Conjugation with Aspartic Acid during Adventitious Root Formation in Pea Cuttings

Nordström

Jacobs²,

Eliasson³

1991

Plant Physiol.

161

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“…We incubated 8-dold seedlings in a solution containing 10 mM [ 13 C 8 -15 N 1 ] IBA and assayed levels of [ 13 C 8 -15 N 1 ]IAA after 1 h by using gas chromatography-mass spectrometry (GC-MS) with selective ion monitoring (SIM). We found that wild-type seedlings converted some of the provided IBA to IAA during the 1-h labeling period, demonstrating that Arabidopsis, like other plants (Epstein and Lavee, 1984;Epstein et al, 1989;Epstein and Ludwig-Mü ller, 1993;Ludwig-Mü ller, 2000), can use IBA as an IAA precursor. Moreover, the tir1-1 and axr2-1 auxin-signaling mutants accumulated similar levels of [ 13 C 8 -15 N 1 ]IAA as wild type (Fig.…”

Section: Iba-resistant Mutants Are Defective In Iba-to-iaa Conversionmentioning

confidence: 61%

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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“…Several studies have demonstrated within the last decade that IBA is present in vascular plants (Epstein et al, 1989;Ludwig-Mü ller andEpstein, 1991, 1993; Ludwig- ). IBA appears to be stored like IAA in a conjugated form with amino acids or sugars , allowing its slow hydrolysis and release.…”

Section: Discussionmentioning

confidence: 99%

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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Identification of indole-3-butyric acid as an endogenous constituent of maize kernels and leaves

Cited by 48 publications

References 13 publications

Effect of Exogenous Indole-3-Acetic Acid and Indole-3-Butyric Acid on Internal Levels of the Respective Auxins and Their Conjugation with Aspartic Acid during Adventitious Root Formation in Pea Cuttings

Effect of Exogenous Indole-3-Acetic Acid and Indole-3-Butyric Acid on Internal Levels of the Respective Auxins and Their Conjugation with Aspartic Acid during Adventitious Root Formation in Pea Cuttings

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

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