Auxin Signaling, Transport, and Metabolism

A special issue of Plants (ISSN 2223-7747).

Deadline for manuscript submissions: closed (30 September 2013) | Viewed by 50228

Special Issue Editor


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Guest Editor
Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093-0116, USA
Interests: auxin; Arabidopsis; plant hormones; plant development; signal transduction; genetics; enzymology

Special Issue Information

Dear Colleagues,

Auxin is an essential hormone for almost every aspect of plant growth and development. Much progress has been made in the field of auxin biology in the past few years. The main pathways / genes responsible for auxin biosynthesis, conjugation, transport, and signaling have been discovered using genetic, molecular, and biochemical approaches in Arabidopsis. For auxin signaling, it appears that there are two separate pathways that regulate transcriptional and non-transcriptional auxin signaling. The recent identification of a complete auxin biosynthesis pathway provides tools for manipulating auxin levels in plants with spatial and temporal precision. Despite of the progresses, it is still far from clear how plants integrate auxin biosynthesis, metabolism, and transport to create auxin gradients for plant developmental processes.

This Special Issue hopes to highlight the recent development in auxin biology. Contributions related to auxin biosynthesis, conjugation, metabolism, transport, and signaling are welcome. Studies addressing the fundamental mechanisms by which auxin controls plant growth and development are also appropriate. Development of tools for auxin research and application of auxin biology in agriculture will be considered as well.

Prof. Dr. Yunde Zhao
Guest Editor

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Keywords

  • auxin
  • polar auxin transport
  • auxin biosynthesis
  • auxin signaling
  • GH3
  • auxin conjugates
  • root development
  • vascular patterning
  • auxin gradient
  • embryogenesis
  • PIN-FORMED

Published Papers (5 papers)

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Research

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2380 KiB  
Article
Characterization of Four Bifunctional Plant IAM/PAM-Amidohydrolases Capable of Contributing to Auxin Biosynthesis
by Beatriz Sánchez-Parra, Henning Frerigmann, Marta-Marina Pérez Alonso, Víctor Carrasco Loba, Ricarda Jost, Mathias Hentrich and Stephan Pollmann
Plants 2014, 3(3), 324-347; https://doi.org/10.3390/plants3030324 - 07 Aug 2014
Cited by 22 | Viewed by 10819
Abstract
Amidases [EC 3.5.1.4] capable of converting indole-3-acetamide (IAM) into the major plant growth hormone indole-3-acetic acid (IAA) are assumed to be involved in auxin de novo biosynthesis. With the emerging amount of genomics data, it was possible to identify over forty proteins with [...] Read more.
Amidases [EC 3.5.1.4] capable of converting indole-3-acetamide (IAM) into the major plant growth hormone indole-3-acetic acid (IAA) are assumed to be involved in auxin de novo biosynthesis. With the emerging amount of genomics data, it was possible to identify over forty proteins with substantial homology to the already characterized amidases from Arabidopsis and tobacco. The observed high conservation of amidase-like proteins throughout the plant kingdom may suggest an important role of theses enzymes in plant development. Here, we report cloning and functional analysis of four, thus far, uncharacterized plant amidases from Oryza sativa, Sorghum bicolor, Medicago truncatula, and Populus trichocarpa. Intriguingly, we were able to demonstrate that the examined amidases are also capable of converting phenyl-2-acetamide (PAM) into phenyl-2-acetic acid (PAA), an auxin endogenous to several plant species including Arabidopsis. Furthermore, we compared the subcellular localization of the enzymes to that of Arabidopsis AMI1, providing further evidence for similar enzymatic functions. Our results point to the presence of a presumably conserved pathway of auxin biosynthesis via IAM, as amidases, both of monocot, and dicot origins, were analyzed. Full article
(This article belongs to the Special Issue Auxin Signaling, Transport, and Metabolism)
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1374 KiB  
Article
LEAFY and Polar Auxin Transport Coordinately Regulate Arabidopsis Flower Development
by Nobutoshi Yamaguchi, Miin-Feng Wu, Cara M. Winter and Doris Wagner
Plants 2014, 3(2), 251-265; https://doi.org/10.3390/plants3020251 - 30 Apr 2014
Cited by 24 | Viewed by 10843
Abstract
The plant specific transcription factor LEAFY (LFY) plays a pivotal role in the developmental switch to floral meristem identity in Arabidopsis. Our recent study revealed that LFY additionally acts downstream of AUXIN RESPONSE FACTOR5/MONOPTEROS to promote flower primordium initiation. LFY also promotes [...] Read more.
The plant specific transcription factor LEAFY (LFY) plays a pivotal role in the developmental switch to floral meristem identity in Arabidopsis. Our recent study revealed that LFY additionally acts downstream of AUXIN RESPONSE FACTOR5/MONOPTEROS to promote flower primordium initiation. LFY also promotes initiation of the floral organ and floral organ identity. To further investigate the interplay between LFY and auxin during flower development, we examined the phenotypic consequence of disrupting polar auxin transport in lfy mutants by genetic means. Plants with compromised LFY activity exhibit increased sensitivity to disruption of polar auxin transport. Compromised polar auxin transport activity in the lfy mutant background resulted in formation of fewer floral organs, abnormal gynoecium development, and fused sepals. In agreement with these observations, expression of the auxin response reporter DR5rev::GFP as well as of the direct LFY target CUP-SHAPED COTYLEDON2 were altered in lfy mutant flowers. We also uncovered reduced expression of ETTIN, a regulator of gynoecium development and a direct LFY target. Our results suggest that LFY and polar auxin transport coordinately modulate flower development by regulating genes required for elaboration of the floral organs. Full article
(This article belongs to the Special Issue Auxin Signaling, Transport, and Metabolism)
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840 KiB  
Article
Auxin and Cell Wall Invertase Related Signaling during Rice Grain Development
by Sarah Russell French, Yousef Abu-Zaitoon, Md. Myn Uddin, Karina Bennett and Heather M. Nonhebel
Plants 2014, 3(1), 95-112; https://doi.org/10.3390/plants3010095 - 07 Feb 2014
Cited by 27 | Viewed by 8914
Abstract
Indole-3-acetic acid (IAA) synthesis is required for grain-fill in maize and appears to be regulated by cell-wall invertase (CWIN) activity. OsYUC12 is one of three IAA biosynthesis genes we previously reported as expressed during early rice grain development, correlating with a large increase [...] Read more.
Indole-3-acetic acid (IAA) synthesis is required for grain-fill in maize and appears to be regulated by cell-wall invertase (CWIN) activity. OsYUC12 is one of three IAA biosynthesis genes we previously reported as expressed during early rice grain development, correlating with a large increase in IAA content of the grain. This work aimed to investigate further the role of OsYUC12 and its relationship to CWIN activity and invertase inhibitors (INVINH). The analysis shows a brief peak of OsYUC12 expression early in endosperm development. Meta-analysis of microarray data, confirmed by quantitative expression analysis, revealed that OsYUC12 is coexpressed with OsIAA29, which encodes an unusual AUX/IAA transcription factor previously reported as poorly expressed. Maximum expression of OsYUC12 and OsIAA29 coincided with maximum CWIN activity, but also with a peak in INVINH expression. Unlike ZmYUC1, OsYUC12 expression is not reduced in the rice CWIN mutant, gif1. Several reports have investigated CWIN expression in rice grains but none has reported on expression of INVINH in this species. We show that rice has 54 genes encoding putative invertase/pectin methylesterase inhibitors, seven of which are expressed exclusively during grain development. Our results suggest a more complex relationship between IAA, CWIN, and INVINH than previously proposed. Full article
(This article belongs to the Special Issue Auxin Signaling, Transport, and Metabolism)
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Article
The Clubroot Pathogen (Plasmodiophora brassicae) Influences Auxin Signaling to Regulate Auxin Homeostasis in Arabidopsis
by Linda Jahn, Stefanie Mucha, Sabine Bergmann, Cornelia Horn, Paul Staswick, Bianka Steffens, Johannes Siemens and Jutta Ludwig-Müller
Plants 2013, 2(4), 726-749; https://doi.org/10.3390/plants2040726 - 27 Nov 2013
Cited by 46 | Viewed by 11705
Abstract
The clubroot disease, caused by the obligate biotrophic protist Plasmodiophora brassicae, affects cruciferous crops worldwide. It is characterized by root swellings as symptoms, which are dependent on the alteration of auxin and cytokinin metabolism. Here, we describe that two different classes of [...] Read more.
The clubroot disease, caused by the obligate biotrophic protist Plasmodiophora brassicae, affects cruciferous crops worldwide. It is characterized by root swellings as symptoms, which are dependent on the alteration of auxin and cytokinin metabolism. Here, we describe that two different classes of auxin receptors, the TIR family and the auxin binding protein 1 (ABP1) in Arabidopsis thaliana are transcriptionally upregulated upon gall formation. Mutations in the TIR family resulted in more susceptible reactions to the root pathogen. As target genes for the different pathways we have investigated the transcriptional regulation of selected transcriptional repressors (Aux/IAA) and transcription factors (ARF). As the TIR pathway controls auxin homeostasis via the upregulation of some auxin conjugate synthetases (GH3), the expression of selected GH3 genes was also investigated, showing in most cases upregulation. A double gh3 mutant showed also slightly higher susceptibility to P. brassicae infection, while all tested single mutants did not show any alteration in the clubroot phenotype. As targets for the ABP1-induced cell elongation the effect of potassium channel blockers on clubroot formation was investigated. Treatment with tetraethylammonium (TEA) resulted in less severe clubroot symptoms. This research provides evidence for the involvement of two auxin signaling pathways in Arabidopsis needed for the establishment of the root galls by P. brassicae. Full article
(This article belongs to the Special Issue Auxin Signaling, Transport, and Metabolism)
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526 KiB  
Review
Cellular Auxin Transport in Algae
by Suyun Zhang and Bert Van Duijn
Plants 2014, 3(1), 58-69; https://doi.org/10.3390/plants3010058 - 27 Jan 2014
Cited by 18 | Viewed by 7041
Abstract
The phytohormone auxin is one of the main directors of plant growth and development. In higher plants, auxin is generated in apical plant parts and transported from cell-to-cell in a polar fashion. Auxin is present in all plant phyla, and the existence of [...] Read more.
The phytohormone auxin is one of the main directors of plant growth and development. In higher plants, auxin is generated in apical plant parts and transported from cell-to-cell in a polar fashion. Auxin is present in all plant phyla, and the existence of polar auxin transport (PAT) is well established in land plants. Algae are a group of relatively simple, autotrophic, photosynthetic organisms that share many features with land plants. In particular, Charophyceae (a taxon of green algae) are closest ancestors of land plants. In the study of auxin function, transport and its evolution, the algae form an interesting research target. Recently, proof for polar auxin transport in Chara species was published and auxin related research in algae gained more attention. In this review we discuss auxin transport in algae with respect to land plants and suggest directions for future studies. Full article
(This article belongs to the Special Issue Auxin Signaling, Transport, and Metabolism)
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