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Göran Sandberg - One of the best experts on this subject based on the ideXlab platform.

  • aux1 promotes lateral root formation by facilitating indole 3 acetic Acid distribution between sink and source tissues in the arabidopsis seedling
    The Plant Cell, 2002
    Co-Authors: Alan Marchant, Rishikesh P Bhalerao, Jan Eklof, Pedro J. Casero, Malcolm J Bennett, Ilda Casimiro, Göran Sandberg
    Abstract:

    Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between Indole-3-Acetic Acid (IAA) source and sink tissues. Gas chromatography–selected reaction monitoring–mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic Acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.

  • aux1 promotes lateral root formation by facilitating indole 3 acetic Acid distribution between sink and source tissues in the arabidopsis seedling
    The Plant Cell, 2002
    Co-Authors: Alan Marchant, Rishikesh P Bhalerao, Jan Eklof, Pedro J. Casero, Malcolm J Bennett, Ilda Casimiro, Göran Sandberg
    Abstract:

    Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between Indole-3-Acetic Acid (IAA) source and sink tissues. Gas chromatography–selected reaction monitoring–mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic Acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.

  • identification and biochemical characterization of an arabidopsis indole 3 acetic Acid glucosyltransferase
    Journal of Biological Chemistry, 2001
    Co-Authors: Rosamond G Jackson, Göran Sandberg, Mariusz Kowalczyk, Engkiat Lim, Jim Hoggett, David A Ashford, Dianna J Bowles
    Abstract:

    Abstract Biochemical characterization of recombinant gene products following a phylogenetic analysis of the UDP-glucosyltransferase (UGT) multigene family ofArabidopsis has identified one enzyme (UGT84B1) with high activity toward the plant hormone Indole-3-Acetic Acid (IAA) and three related enzymes (UGT84B2, UGT75B1, and UGT75B2) with trace activities. The identity of the IAA conjugate has been confirmed to be 1-O-indole acetyl glucose ester. A sequence annotated as a UDP-glucose:IAA glucosyltransferase (IAA-UGT) in theArabidopsis genome and expressed sequence tag data bases given its similarity to the maize iaglu gene sequence showed no activity toward IAA. This study describes the first biochemical analysis of a recombinant IAA-UGT and provides the foundation for future genetic approaches to understand the role of 1-O-indole acetyl glucose ester inArabidopsis.

  • a microscale technique for gas chromatography mass spectrometry measurements of picogram amounts of indole 3 acetic Acid in plant tissues
    Plant Physiology, 1995
    Co-Authors: A Edlund, Bjorn Sundberg, Staffan Eklof, Thomas Moritz, Göran Sandberg
    Abstract:

    A microscale technique has been developed for routine quantifications of picogram amounts of Indole-3-Acetic Acid (IAA) in plant tissues by combined gas chromatography-mass spectrometry. Low- and high-resolution selected-ion-monitoring and selected-reaction-monitoring mass spectrometry techniques were compared for selectivity and precision. The best selectivity was obtained with selected-reaction-monitoring analysis, and 1-mg samples containing 500 fg of IAA could be analyzed accurately with this method. This technique was used to investigate the IAA distribution pattern along the longitudinal axis of tobacco (Nicotiana tabacum [L.]) leaves. In young, developing leaves an increase of endogenous IAA from the leaf tip to the base of the leaf was observed, whereas the level of IAA was uniform along this axis in mature leaves.

Elmar W Weiler - One of the best experts on this subject based on the ideXlab platform.

  • tryptophan dependent indole 3 acetic Acid biosynthesis by iaa synthase proceeds via indole 3 acetamide
    Phytochemistry, 2009
    Co-Authors: Stephan Pollmann, Petra Duchting, Elmar W Weiler
    Abstract:

    Abstract Plants are suggested to produce their major growth promoting phytohormone, Indole-3-Acetic Acid (IAA), via multiple redundantly operating pathways. Although great effort has been made and plenty of possible routes have been proposed based on experimental evidence, a complete pathway for IAA production has yet to be demonstrated. In this study, an in-vitro approach was taken to examine the conversion of l -tryptophan ( l -trp) to IAA by gas chromatography-mass spectrometry (GC–MS). Especially the influence of putative reaction intermediates on the enzymatic conversion of l -trp to IAA was analyzed. Among the substances tested only indole-3-acetamide (IAM) showed a pronounced effect on the l -trp conversion. We additionally report that IAM is synthesized from l -trp and that it is further converted to IAA by the utilized cell free Arabidopsis extract. Together, our results underscore the functionality of an IAM-dependent auxin biosynthesis pathway in Arabidopsis thaliana .

  • molecular cloning and characterization of an amidase from arabidopsis thaliana capable of converting indole 3 acetamide into the plant growth hormone indole 3 acetic Acid
    Phytochemistry, 2003
    Co-Authors: Stephan Pollmann, Daniel Neu, Elmar W Weiler
    Abstract:

    Acylamidohydrolases from higher plants have not been characterized or cloned so far. AtAMI1 is the first member of this enzyme family from a higher plant and was identified in the genome of Arabidopsis thaliana based on sequence homology with the catalytic-domain sequence of bacterial acylamidohydrolases, particularly those that exhibit indole-3-acetamide amidohydrolase activity. AtAMI1 polypeptide and mRNA are present in leaf tissues, as shown by immunoblotting and RT-PCR, respectively. AtAMI1 was expressed from its cDNA in enzymatically active form and exhibits substrate specificity for indole-3-acetamide, but also some activity against l-asparagine. The recombinant enzyme was characterized further. The results show that higher plants have acylamidohydrolases with properties similar to the enzymes of certain plant-associated bacteria such as Agrobacterium-, Pseudomonas- and Rhodococcus-species, in which these enzymes serve to synthesize the plant growth hormone, Indole-3-Acetic Acid, utilized by the bacteria to colonize their host plants. As indole-3-acetamide is a native metabolite in Arabidopsis thaliana, it can no longer be ruled out that one pathway for the biosynthesis of Indole-3-Acetic Acid involves indole-3-acetamide-hydrolysis by AtAMI1.

Alan Marchant - One of the best experts on this subject based on the ideXlab platform.

  • aux1 promotes lateral root formation by facilitating indole 3 acetic Acid distribution between sink and source tissues in the arabidopsis seedling
    The Plant Cell, 2002
    Co-Authors: Alan Marchant, Rishikesh P Bhalerao, Jan Eklof, Pedro J. Casero, Malcolm J Bennett, Ilda Casimiro, Göran Sandberg
    Abstract:

    Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between Indole-3-Acetic Acid (IAA) source and sink tissues. Gas chromatography–selected reaction monitoring–mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic Acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.

  • aux1 promotes lateral root formation by facilitating indole 3 acetic Acid distribution between sink and source tissues in the arabidopsis seedling
    The Plant Cell, 2002
    Co-Authors: Alan Marchant, Rishikesh P Bhalerao, Jan Eklof, Pedro J. Casero, Malcolm J Bennett, Ilda Casimiro, Göran Sandberg
    Abstract:

    Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between Indole-3-Acetic Acid (IAA) source and sink tissues. Gas chromatography–selected reaction monitoring–mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic Acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.

Stephan Pollmann - One of the best experts on this subject based on the ideXlab platform.

  • tryptophan dependent indole 3 acetic Acid biosynthesis by iaa synthase proceeds via indole 3 acetamide
    Phytochemistry, 2009
    Co-Authors: Stephan Pollmann, Petra Duchting, Elmar W Weiler
    Abstract:

    Abstract Plants are suggested to produce their major growth promoting phytohormone, Indole-3-Acetic Acid (IAA), via multiple redundantly operating pathways. Although great effort has been made and plenty of possible routes have been proposed based on experimental evidence, a complete pathway for IAA production has yet to be demonstrated. In this study, an in-vitro approach was taken to examine the conversion of l -tryptophan ( l -trp) to IAA by gas chromatography-mass spectrometry (GC–MS). Especially the influence of putative reaction intermediates on the enzymatic conversion of l -trp to IAA was analyzed. Among the substances tested only indole-3-acetamide (IAM) showed a pronounced effect on the l -trp conversion. We additionally report that IAM is synthesized from l -trp and that it is further converted to IAA by the utilized cell free Arabidopsis extract. Together, our results underscore the functionality of an IAM-dependent auxin biosynthesis pathway in Arabidopsis thaliana .

  • molecular cloning and characterization of an amidase from arabidopsis thaliana capable of converting indole 3 acetamide into the plant growth hormone indole 3 acetic Acid
    Phytochemistry, 2003
    Co-Authors: Stephan Pollmann, Daniel Neu, Elmar W Weiler
    Abstract:

    Acylamidohydrolases from higher plants have not been characterized or cloned so far. AtAMI1 is the first member of this enzyme family from a higher plant and was identified in the genome of Arabidopsis thaliana based on sequence homology with the catalytic-domain sequence of bacterial acylamidohydrolases, particularly those that exhibit indole-3-acetamide amidohydrolase activity. AtAMI1 polypeptide and mRNA are present in leaf tissues, as shown by immunoblotting and RT-PCR, respectively. AtAMI1 was expressed from its cDNA in enzymatically active form and exhibits substrate specificity for indole-3-acetamide, but also some activity against l-asparagine. The recombinant enzyme was characterized further. The results show that higher plants have acylamidohydrolases with properties similar to the enzymes of certain plant-associated bacteria such as Agrobacterium-, Pseudomonas- and Rhodococcus-species, in which these enzymes serve to synthesize the plant growth hormone, Indole-3-Acetic Acid, utilized by the bacteria to colonize their host plants. As indole-3-acetamide is a native metabolite in Arabidopsis thaliana, it can no longer be ruled out that one pathway for the biosynthesis of Indole-3-Acetic Acid involves indole-3-acetamide-hydrolysis by AtAMI1.

Ilda Casimiro - One of the best experts on this subject based on the ideXlab platform.

  • aux1 promotes lateral root formation by facilitating indole 3 acetic Acid distribution between sink and source tissues in the arabidopsis seedling
    The Plant Cell, 2002
    Co-Authors: Alan Marchant, Rishikesh P Bhalerao, Jan Eklof, Pedro J. Casero, Malcolm J Bennett, Ilda Casimiro, Göran Sandberg
    Abstract:

    Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between Indole-3-Acetic Acid (IAA) source and sink tissues. Gas chromatography–selected reaction monitoring–mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic Acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.

  • aux1 promotes lateral root formation by facilitating indole 3 acetic Acid distribution between sink and source tissues in the arabidopsis seedling
    The Plant Cell, 2002
    Co-Authors: Alan Marchant, Rishikesh P Bhalerao, Jan Eklof, Pedro J. Casero, Malcolm J Bennett, Ilda Casimiro, Göran Sandberg
    Abstract:

    Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between Indole-3-Acetic Acid (IAA) source and sink tissues. Gas chromatography–selected reaction monitoring–mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic Acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.