Special Issue "Auxin Signaling, Transport, and Metabolism"

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

Deadline for manuscript submissions: closed (30 September 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Yunde Zhao (Website)

Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093-0116, USA
Fax: +1-858-534-7108
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

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Plants is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 300 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

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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Open AccessArticle Characterization of Four Bifunctional Plant IAM/PAM-Amidohydrolases Capable of Contributing to Auxin Biosynthesis
Plants 2014, 3(3), 324-347; doi:10.3390/plants3030324
Received: 6 February 2014 / Revised: 23 July 2014 / Accepted: 30 July 2014 / Published: 7 August 2014
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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 [...] 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)
Open AccessArticle LEAFY and Polar Auxin Transport Coordinately Regulate Arabidopsis Flower Development
Plants 2014, 3(2), 251-265; doi:10.3390/plants3020251
Received: 13 January 2014 / Revised: 6 April 2014 / Accepted: 23 April 2014 / Published: 30 April 2014
Cited by 1 | PDF Full-text (1374 KB) | HTML Full-text | XML Full-text
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 [...] 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)
Open AccessArticle Auxin and Cell Wall Invertase Related Signaling during Rice Grain Development
Plants 2014, 3(1), 95-112; doi:10.3390/plants3010095
Received: 29 September 2013 / Revised: 13 January 2014 / Accepted: 15 January 2014 / Published: 7 February 2014
Cited by 2 | PDF Full-text (840 KB) | HTML Full-text | XML Full-text | Supplementary Files
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 [...] 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)
Figures

Open AccessArticle The Clubroot Pathogen (Plasmodiophora brassicae) Influences Auxin Signaling to Regulate Auxin Homeostasis in Arabidopsis
Plants 2013, 2(4), 726-749; doi:10.3390/plants2040726
Received: 16 September 2013 / Revised: 17 October 2013 / Accepted: 18 November 2013 / Published: 27 November 2013
Cited by 7 | PDF Full-text (1503 KB) | HTML Full-text | XML Full-text | Supplementary Files
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 [...] 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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Review

Jump to: Research

Open AccessReview Cellular Auxin Transport in Algae
Plants 2014, 3(1), 58-69; doi:10.3390/plants3010058
Received: 3 December 2013 / Revised: 20 December 2013 / Accepted: 14 January 2014 / Published: 27 January 2014
Cited by 5 | PDF Full-text (526 KB) | HTML Full-text | XML Full-text
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 [...] 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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