Sites and Regulation of Auxin Biosynthesis in Arabidopsis Roots

Ljung, Karin; Hull, Anna K.; Celenza, John L.; Yamada, Masashi; Estelle, Mark; Normanly, Jennifer; Sandberg, Göran

doi:10.1105/tpc.104.029272

Cited by 478 publications

(436 citation statements)

References 64 publications

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“…4). Amazingly, the same root regions with GUS activity accumulate both flavonoids and auxins (Murphy and Taiz, 1999;Murphy et al, 2000;Peer et al, 2001;Ljung et al, 2005). In this context, it should be stressed that, in Arabidopsis roots, ChS and chalcone isomerase (Saslowsky and Winkel-Shirley, 2001) are located in sites where the PvACCase gene promoter is active (Fig.…”

Section: Discussionmentioning

confidence: 98%

Hormonal and Stress Induction of the Gene Encoding Common Bean Acetyl-Coenzyme A Carboxylase

2006

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Regulation of the cytosolic acetyl-coenzyme A carboxylase (ACCase) gene promoter from common bean (Phaseolus vulgaris) was studied in transgenic Arabidopsis (Arabidopsis thaliana) plants using a β-glucuronidase (GUS) reporter gene fusion (PvACCase∷GUS). Under normal growth conditions, GUS was expressed in hydathodes, stipules, trichome bases, flowers, pollen, and embryos. In roots, expression was observed in the tip, elongation zone, hypocotyl-root transition zone, and lateral root primordia. The PvACCase promoter was induced by wounding, Pseudomonas syringae infection, hydrogen peroxide, jasmonic acid (JA), ethylene, or auxin treatment. Analysis of PvACCase∷GUS expression in JA and ethylene mutants (coronatine insensitive1-1 [coi1-1], ethylene resistant1-1 [etr1-1], coi1-1/etr1-1) suggests that neither JA nor ethylene perception participates in the activation of this gene in response to wounding, although each of these independent signaling pathways is sufficient for pathogen or hydrogen peroxide-induced PvACCase gene expression. We propose a model involving different pathways of PvACCase gene activation in response to stress.

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Section: Discussionmentioning

confidence: 98%

Hormonal and Stress Induction of the Gene Encoding Common Bean Acetyl-Coenzyme A Carboxylase

2006

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“…Four replicates of the samples were purified after the addition of 250 picograms 13 C6-IAA internal standard and analyzed by gas chromatography-selected reaction monitoring mass spectrometry as described (Ljung et al, 2005).…”

Section: Iaa Measurementmentioning

confidence: 99%

Coordination between Apoplastic and Symplastic Detoxification Confers Plant Aluminum Resistance

et al. 2013

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Whether aluminum toxicity is an apoplastic or symplastic phenomenon is still a matter of debate. Here, we found that three auxin overproducing mutants, yucca, the recessive mutant superroot2, and superroot1 had increased aluminum sensitivity, while a transfer DNA insertion mutant, xyloglucan endotransglucosylase/hydrolases15 (xth15), showed enhanced aluminum resistance, accompanied by low endogenous indole-3-acetic acid levels, implying that auxin may be involved in plant responses to aluminum stress. We used yucca and xth15 mutants for further study. The two mutants accumulated similar total aluminum in roots and had significantly reduced cell wall aluminum and increased symplastic aluminum content relative to the wild-type ecotype Columbia, indicating that altered aluminum levels in the symplast or cell wall cannot fully explain the differential aluminum resistance of these two mutants. The expression of Al sensitive1 (ALS1), a gene that functions in aluminum redistribution between the cytoplasm and vacuole and contributes to symplastic aluminum detoxification, was less abundant in yucca and more abundant in xth15 than the wild type, consistent with possible ALS1 function conferring altered aluminum sensitivity in the two mutants. Consistent with the idea that xth15 can tolerate more symplastic aluminum because of possible ALS1 targeting to the vacuole, morin staining of yucca root tip sections showed more aluminum accumulation in the cytosol than in the wild type, and xth15 showed reduced morin staining of cytosolic aluminum, even though yucca and xth15 had similar overall symplastic aluminum content. Exogenous application of an active auxin analog, naphthylacetic acid, to the wild type mimicked the aluminum sensitivity and distribution phenotypes of yucca, verifying that auxin may regulate aluminum distribution in cells.Together, these data demonstrate that auxin negatively regulates aluminum tolerance through altering ALS1 expression and aluminum distribution within plant cells, and plants must coordinate exclusion and internal detoxification to reduce aluminum toxicity effectively.

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“…To investigate whether there was a reduction in the accumulation and/or synthesis of auxin in mutant root tissues, we analyzed indole-3-acetic acid (IAA) concentration and biosynthesis rate in the root apex of wild-type and shr seedlings during the first 10 d of germination using mass spectrometry (as described by Edlund et al [1995] and Ljung et al [2005]). Surprisingly, IAA concentration was significantly elevated in shr root tips compared with the wild type in seedlings at 3 and 6 d after germination (DAG; pooled 1-mm root tips; Fig.…”

Section: The Shr Mutant Fails To Reinitiate Cell Division In the Primmentioning

confidence: 99%

“…Seedlings were grown on vertical agar plates under long-day conditions as described by Ljung et al (2005). IAA quantification was performed on shr and…”

Section: Iaa Quantification and Biosynthesis Measurementsmentioning

confidence: 99%

SHORT-ROOT Regulates Primary, Lateral, and Adventitious Root Development in Arabidopsis

et al. 2010

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SHORT-ROOT (SHR) is a well-characterized regulator of radial patterning and indeterminacy of the Arabidopsis (Arabidopsis thaliana) primary root. However, its role during the elaboration of root system architecture remains unclear. We report that the indeterminate wild-type Arabidopsis root system was transformed into a determinate root system in the shr mutant when growing in soil or agar. The root growth behavior of the shr mutant results from its primary root apical meristem failing to initiate cell division following germination. The inability of shr to reactivate mitotic activity in the root apical meristem is associated with the progressive reduction in the abundance of auxin efflux carriers, PIN-FORMED1 (PIN1), PIN2, PIN3, PIN4, and PIN7. The loss of primary root growth in shr is compensated by the activation of anchor root primordia, whose tissues are radially patterned like the wild type. However, SHR function is not restricted to the primary root but is also required for the initiation and patterning of lateral root primordia. In addition, SHR is necessary to maintain the indeterminate growth of lateral and anchor roots. We conclude that SHR regulates a wide array of Arabidopsis root-related developmental processes.

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Sites and Regulation of Auxin Biosynthesis in Arabidopsis Roots

Cited by 478 publications

References 64 publications

Hormonal and Stress Induction of the Gene Encoding Common Bean Acetyl-Coenzyme A Carboxylase

Hormonal and Stress Induction of the Gene Encoding Common Bean Acetyl-Coenzyme A Carboxylase

Coordination between Apoplastic and Symplastic Detoxification Confers Plant Aluminum Resistance

SHORT-ROOT Regulates Primary, Lateral, and Adventitious Root Development in Arabidopsis

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