1
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Smith ES, Nimchuk ZL. What a tangled web it weaves: auxin coordination of stem cell maintenance and flower production. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:6950-6963. [PMID: 37661937 PMCID: PMC10690728 DOI: 10.1093/jxb/erad340] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/25/2023] [Indexed: 09/05/2023]
Abstract
Robust agricultural yields require consistent flower production throughout fluctuating environmental conditions. Floral primordia are produced in the inflorescence meristem, which contains a pool of continuously dividing stem cells. Daughter cells of these divisions either retain stem cell identity or are pushed to the SAM periphery, where they become competent to develop into floral primordia after receiving the appropriate signal. Thus, flower production is inherently linked to regulation of the stem cell pool. The plant hormone auxin promotes flower development throughout its early phases and has been shown to interact with the molecular pathways regulating stem cell maintenance. Here, we will summarize how auxin signaling contributes to stem cell maintenance and promotes flower development through the early phases of initiation, outgrowth, and floral fate establishment. Recent advances in this area suggest that auxin may serve as a signal that integrates stem cell maintenance and new flower production.
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Affiliation(s)
- Elizabeth Sarkel Smith
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Zachary L Nimchuk
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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2
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García-González J, Lacek J, Weckwerth W, Retzer K. Throttling Growth Speed: Evaluation of aux1-7 Root Growth Profile by Combining D-Root system and Root Penetration Assay. PLANTS 2022; 11:plants11050650. [PMID: 35270119 PMCID: PMC8912881 DOI: 10.3390/plants11050650] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 01/16/2023]
Abstract
Directional root growth control is crucial for plant fitness. The degree of root growth deviation depends on several factors, whereby exogenous growth conditions have a profound impact. The perception of mechanical impedance by wild-type roots results in the modulation of root growth traits, and it is known that gravitropic stimulus influences distinct root movement patterns in concert with mechanoadaptation. Mutants with reduced shootward auxin transport are described as being numb towards mechanostimulus and gravistimulus, whereby different growth conditions on agar-supplemented medium have a profound effect on how much directional root growth and root movement patterns differ between wild types and mutants. To reduce the impact of unilateral mechanostimulus on roots grown along agar-supplemented medium, we compared the root movement of Col-0 and auxin resistant 1-7 in a root penetration assay to test how both lines adjust the growth patterns of evenly mechanostimulated roots. We combined the assay with the D-root system to reduce light-induced growth deviation. Moreover, the impact of sucrose supplementation in the growth medium was investigated because exogenous sugar enhances root growth deviation in the vertical direction. Overall, we observed a more regular growth pattern for Col-0 but evaluated a higher level of skewing of aux1-7 compared to the wild type than known from published data. Finally, the tracking of the growth rate of the gravistimulated roots revealed that Col-0 has a throttling elongation rate during the bending process, but aux1-7 does not.
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Affiliation(s)
- Judith García-González
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic; (J.G.-G.); (J.L.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Jozef Lacek
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic; (J.G.-G.); (J.L.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Wolfram Weckwerth
- Department of Functional and Evolutionary Ecology, Molecular Systems Biology (MoSys), Faculty of Life Sciences, University of Vienna, Djerassiplatz 1, 1030 Wien, Austria;
- Vienna Metabolomics Center (VIME), University of Vienna, Djerassiplatz 1, 1030 Wien, Austria
| | - Katarzyna Retzer
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic; (J.G.-G.); (J.L.)
- Correspondence:
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3
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Aliaga Fandino AC, Hardtke CS. Auxin transport in developing protophloem: A case study in canalization. JOURNAL OF PLANT PHYSIOLOGY 2022; 269:153594. [PMID: 34953411 DOI: 10.1016/j.jplph.2021.153594] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 11/03/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
Spatiotemporal cues orchestrate the development of organs and cellular differentiation in multicellular organisms. For instance, in the root apical meristem an auxin gradient patterns the transition from stem cell maintenance to transit amplification and eventual differentiation. Among the proximal tissues generated by this growth apex, the early, so-called protophloem, is the first tissue to differentiate. This observation has been linked to increased auxin activity in the developing protophloem sieve element cell files as compared to the neighboring tissues. Here we review recent progress in the characterization of the unique mechanism by which auxin canalizes its activity in the developing protophloem and fine-tunes its own transport to guide proper timing of protophloem sieve element differentiation.
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Affiliation(s)
- Ana Cecilia Aliaga Fandino
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
| | - Christian S Hardtke
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland.
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4
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Larriba E, Sánchez-García AB, Justamante MS, Martínez-Andújar C, Albacete A, Pérez-Pérez JM. Dynamic Hormone Gradients Regulate Wound-Induced de novo Organ Formation in Tomato Hypocotyl Explants. Int J Mol Sci 2021; 22:11843. [PMID: 34769274 PMCID: PMC8584571 DOI: 10.3390/ijms222111843] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/20/2021] [Accepted: 10/28/2021] [Indexed: 01/24/2023] Open
Abstract
Plants have a remarkable regenerative capacity, which allows them to survive tissue damage after biotic and abiotic stresses. In this study, we use Solanum lycopersicum 'Micro-Tom' explants as a model to investigate wound-induced de novo organ formation, as these explants can regenerate the missing structures without the exogenous application of plant hormones. Here, we performed simultaneous targeted profiling of 22 phytohormone-related metabolites during de novo organ formation and found that endogenous hormone levels dynamically changed after root and shoot excision, according to region-specific patterns. Our results indicate that a defined temporal window of high auxin-to-cytokinin accumulation in the basal region of the explants was required for adventitious root formation and that was dependent on a concerted regulation of polar auxin transport through the hypocotyl, of local induction of auxin biosynthesis, and of local inhibition of auxin degradation. In the apical region, though, a minimum of auxin-to-cytokinin ratio is established shortly after wounding both by decreasing active auxin levels and by draining auxin via its basipetal transport and internalization. Cross-validation with transcriptomic data highlighted the main hormonal gradients involved in wound-induced de novo organ formation in tomato hypocotyl explants.
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Affiliation(s)
- Eduardo Larriba
- Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain; (E.L.); (A.B.S.-G.); (M.S.J.)
| | - Ana Belén Sánchez-García
- Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain; (E.L.); (A.B.S.-G.); (M.S.J.)
| | - María Salud Justamante
- Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain; (E.L.); (A.B.S.-G.); (M.S.J.)
| | - Cristina Martínez-Andújar
- CEBAS-CSIC, Department of Plant Nutrition, Campus Universitario de Espinardo, 30100 Murcia, Spain; (C.M.-A.); (A.A.)
| | - Alfonso Albacete
- CEBAS-CSIC, Department of Plant Nutrition, Campus Universitario de Espinardo, 30100 Murcia, Spain; (C.M.-A.); (A.A.)
| | - José Manuel Pérez-Pérez
- Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain; (E.L.); (A.B.S.-G.); (M.S.J.)
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5
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Kim K, Kim C, Park J, Jeon HJ, Park YJ, Kim YH, Yang JO, Lee SE. Transcriptomic evaluation on methyl bromide-induced phytotoxicity in Arabidopsis thaliana and its mode of phytotoxic action via the occurrence of reactive oxygen species and uneven distribution of auxin hormones. JOURNAL OF HAZARDOUS MATERIALS 2021; 419:126419. [PMID: 34171674 DOI: 10.1016/j.jhazmat.2021.126419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/29/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
The increase in worldwide trade has caused the quality maintenance of commercialized agriproducts to be crucial in keeping its economic value. In recent years, methyl bromide (MB) has been used dominantly during quarantine and pre-shipment, despite it being an environmental hazard with global repercussions. Through this study, it was shown that Arabidopsis thaliana's 2 h exposure to the MB treatment displayed no signs of phytotoxicity, whereas its 4 h exposure significantly interfered with growth. The transcriptomic analysis found the molecular modifications in A. thaliana after the MB fumigation with the up-regulation of genes specifically relative to the abiotic and oxidative stress, and the down-regulation of auxin transporter genes. Some important gene expressions were verified by RT-qPCR and their expression patterns were similar. Oxidative stresses via the reactive oxygen species (ROS) in relation to MB phytotoxicity were confirmed with the increased malondialdehyde in MB-4h-treated A. thaliana. Uneven distribution of auxins via lower expression of auxin transporter genes was also determined using UPLC-ESI-QqQ MS. Application of two ROS scavengers such as N-acetyl-cysteine and L-glutathione minimized MB phytotoxic effect in A. thaliana. Therefore, MB caused severe oxidative stress, and alternatives regarding the use of MB should be considered.
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Affiliation(s)
- Kyeongnam Kim
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Chaeeun Kim
- Department of Integrative Biology, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jungeun Park
- Department of Integrative Biology, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Hwang-Ju Jeon
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Young Ju Park
- Plant Quarantine Technology Center, Animal and Plant Quarantine Agency, Gimcheon 39660, Republic of Korea
| | - Yoon-Ha Kim
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jeong Oh Yang
- Plant Quarantine Technology Center, Animal and Plant Quarantine Agency, Gimcheon 39660, Republic of Korea
| | - Sung-Eun Lee
- Department of Applied Biosciences, Kyungpook National University, Daegu 41566, Republic of Korea; Department of Integrative Biology, Kyungpook National University, Daegu 41566, Republic of Korea.
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6
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Integrating the Roles for Cytokinin and Auxin in De Novo Shoot Organogenesis: From Hormone Uptake to Signaling Outputs. Int J Mol Sci 2021; 22:ijms22168554. [PMID: 34445260 PMCID: PMC8395325 DOI: 10.3390/ijms22168554] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/01/2021] [Accepted: 08/03/2021] [Indexed: 12/01/2022] Open
Abstract
De novo shoot organogenesis (DNSO) is a procedure commonly used for the in vitro regeneration of shoots from a variety of plant tissues. Shoot regeneration occurs on nutrient media supplemented with the plant hormones cytokinin (CK) and auxin, which play essential roles in this process, and genes involved in their signaling cascades act as master regulators of the different phases of shoot regeneration. In the last 20 years, the genetic regulation of DNSO has been characterized in detail. However, as of today, the CK and auxin signaling events associated with shoot regeneration are often interpreted as a consequence of these hormones simply being present in the regeneration media, whereas the roles for their prior uptake and transport into the cultivated plant tissues are generally overlooked. Additionally, sucrose, commonly added to the regeneration media as a carbon source, plays a signaling role and has been recently shown to interact with CK and auxin and to affect the efficiency of shoot regeneration. In this review, we provide an integrative interpretation of the roles for CK and auxin in the process of DNSO, adding emphasis on their uptake from the regeneration media and their interaction with sucrose present in the media to their complex signaling outputs that mediate shoot regeneration.
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7
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Abstract
Molecular genetic and structural studies have revealed the mechanisms of fundamental components of key auxin regulatory pathways consisting of auxin biosynthesis, transport, and signaling. Chemical biology methods applied in auxin research have been greatly expanded through the understanding of auxin regulatory pathways. Many small-molecule modulators of auxin metabolism, transport, and signaling have been generated on the basis of the outcomes of genetic and structural studies on auxin regulatory pathways. These chemical modulators are now widely used as essential tools for dissecting auxin biology in diverse plants. This review covers the structures, primary targets, modes of action, and applications of chemical tools in auxin biosynthesis, transport, and signaling.
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Affiliation(s)
- Ken-Ichiro Hayashi
- Department of Biochemistry, Okayama University of Science, Okayama City 700-0005, Japan
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8
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Cytokinin-Controlled Gradient Distribution of Auxin in Arabidopsis Root Tip. Int J Mol Sci 2021; 22:ijms22083874. [PMID: 33918090 PMCID: PMC8069370 DOI: 10.3390/ijms22083874] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/04/2021] [Accepted: 04/06/2021] [Indexed: 01/21/2023] Open
Abstract
The plant root is a dynamic system, which is able to respond promptly to external environmental stimuli by constantly adjusting its growth and development. A key component regulating this growth and development is the finely tuned cross-talk between the auxin and cytokinin phytohormones. The gradient distribution of auxin is not only important for the growth and development of roots, but also for root growth in various response. Recent studies have shed light on the molecular mechanisms of cytokinin-mediated regulation of local auxin biosynthesis/metabolism and redistribution in establishing active auxin gradients, resulting in cell division and differentiation in primary root tips. In this review, we focus our attention on the molecular mechanisms underlying the cytokinin-controlled auxin gradient in root tips.
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9
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Retzer K, Weckwerth W. The TOR-Auxin Connection Upstream of Root Hair Growth. PLANTS (BASEL, SWITZERLAND) 2021; 10:150. [PMID: 33451169 PMCID: PMC7828656 DOI: 10.3390/plants10010150] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 01/09/2021] [Accepted: 01/11/2021] [Indexed: 12/11/2022]
Abstract
Plant growth and productivity are orchestrated by a network of signaling cascades involved in balancing responses to perceived environmental changes with resource availability. Vascular plants are divided into the shoot, an aboveground organ where sugar is synthesized, and the underground located root. Continuous growth requires the generation of energy in the form of carbohydrates in the leaves upon photosynthesis and uptake of nutrients and water through root hairs. Root hair outgrowth depends on the overall condition of the plant and its energy level must be high enough to maintain root growth. TARGET OF RAPAMYCIN (TOR)-mediated signaling cascades serve as a hub to evaluate which resources are needed to respond to external stimuli and which are available to maintain proper plant adaptation. Root hair growth further requires appropriate distribution of the phytohormone auxin, which primes root hair cell fate and triggers root hair elongation. Auxin is transported in an active, directed manner by a plasma membrane located carrier. The auxin efflux carrier PIN-FORMED 2 is necessary to transport auxin to root hair cells, followed by subcellular rearrangements involved in root hair outgrowth. This review presents an overview of events upstream and downstream of PIN2 action, which are involved in root hair growth control.
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Affiliation(s)
- Katarzyna Retzer
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic
| | - Wolfram Weckwerth
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, University of Vienna, 1010 Vienna, Austria;
- Vienna Metabolomics Center (VIME), University of Vienna, 1010 Vienna, Austria
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10
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Vosolsobě S, Skokan R, Petrášek J. The evolutionary origins of auxin transport: what we know and what we need to know. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3287-3295. [PMID: 32246155 DOI: 10.1093/jxb/eraa169] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 04/02/2020] [Indexed: 05/24/2023]
Abstract
Auxin, represented by indole-3-acetic acid (IAA), has for a long time been studied mainly with respect to the development of land plants, and recent evidence confirms that canonical nuclear auxin signaling is a land plant apomorphy. Increasing sequential and physiological data show that the presence of auxin transport machinery pre-dates the emergence of canonical signaling. In this review, we summarize the present state of knowledge regarding the origins of auxin transport in the green lineage (Viridiplantae), integrating both data from wet lab experiments and sequence evidence on the presence of PIN-FORMED (PIN), PIN-LIKES (PILS), and AUXIN RESISTANT 1/LIKE-AUX1 (AUX1/LAX) homologs. We discuss a high divergence of auxin carrier homologs among algal lineages and emphasize the urgent need for the establishment of good molecular biology models from within the streptophyte green algae. We further postulate and discuss two hypotheses for the ancestral role of auxin in the green lineage. First, auxin was present as a by-product of cell metabolism and the evolution of its transport was stimulated by the need for IAA sequestration and cell detoxification. Second, auxin was primarily a signaling compound, possibly of bacterial origin, and its activity in the pre-plant green algae was a consequence of long-term co-existence with bacteria in shared ecological consortia.
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Affiliation(s)
- Stanislav Vosolsobě
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná, Czech Republic
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová, Czech Republic
| | - Roman Skokan
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná, Czech Republic
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová, Czech Republic
| | - Jan Petrášek
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná, Czech Republic
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová, Czech Republic
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11
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Semeradova H, Montesinos JC, Benkova E. All Roads Lead to Auxin: Post-translational Regulation of Auxin Transport by Multiple Hormonal Pathways. PLANT COMMUNICATIONS 2020; 1:100048. [PMID: 33367243 PMCID: PMC7747973 DOI: 10.1016/j.xplc.2020.100048] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/26/2020] [Accepted: 04/18/2020] [Indexed: 05/03/2023]
Abstract
Auxin is a key hormonal regulator, that governs plant growth and development in concert with other hormonal pathways. The unique feature of auxin is its polar, cell-to-cell transport that leads to the formation of local auxin maxima and gradients, which coordinate initiation and patterning of plant organs. The molecular machinery mediating polar auxin transport is one of the important points of interaction with other hormones. Multiple hormonal pathways converge at the regulation of auxin transport and form a regulatory network that integrates various developmental and environmental inputs to steer plant development. In this review, we discuss recent advances in understanding the mechanisms that underlie regulation of polar auxin transport by multiple hormonal pathways. Specifically, we focus on the post-translational mechanisms that contribute to fine-tuning of the abundance and polarity of auxin transporters at the plasma membrane and thereby enable rapid modification of the auxin flow to coordinate plant growth and development.
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Affiliation(s)
- Hana Semeradova
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | | | - Eva Benkova
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
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12
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The dynamic response of the Arabidopsis root metabolome to auxin and ethylene is not predicted by changes in the transcriptome. Sci Rep 2020; 10:679. [PMID: 31959762 PMCID: PMC6971091 DOI: 10.1038/s41598-019-57161-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/19/2019] [Indexed: 12/27/2022] Open
Abstract
While the effects of phytohormones on plant gene expression have been well characterized, comparatively little is known about how hormones influence metabolite profiles. This study examined the effects of elevated auxin and ethylene on the metabolome of Arabidopsis roots using a high-resolution 24 h time course, conducted in parallel to time-matched transcriptomic analyses. Mass spectrometry using orthogonal UPLC separation strategies (reversed phase and HILIC) in both positive and negative ionization modes was used to maximize identification of metabolites with altered levels. The findings show that the root metabolome responds rapidly to hormone stimulus and that compounds belonging to the same class of metabolites exhibit similar changes. The responses were dominated by changes in phenylpropanoid, glucosinolate, and fatty acid metabolism, although the nature and timing of the response was unique for each hormone. These alterations in the metabolome were not directly predicted by the corresponding transcriptome data, suggesting that post-transcriptional events such as changes in enzyme activity and/or transport processes drove the observed changes in the metabolome. These findings underscore the need to better understand the biochemical mechanisms underlying the temporal reconfiguration of plant metabolism, especially in relation to the hormone-metabolome interface and its subsequent physiological and morphological effects.
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13
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Müller K, Hošek P, Laňková M, Vosolsobě S, Malínská K, Čarná M, Fílová M, Dobrev PI, Helusová M, Hoyerová K, Petrášek J. Transcription of specific auxin efflux and influx carriers drives auxin homeostasis in tobacco cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 100:627-640. [PMID: 31349380 DOI: 10.1111/tpj.14474] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/08/2019] [Accepted: 07/12/2019] [Indexed: 06/10/2023]
Abstract
Auxin concentration gradients are informative for the transduction of many developmental cues, triggering downstream gene expression and other responses. The generation of auxin gradients depends significantly on cell-to-cell auxin transport, which is supported by the activities of auxin efflux and influx carriers. However, at the level of individual plant cell, the co-ordination of auxin efflux and influx largely remains uncharacterized. We addressed this issue by analyzing the contribution of canonical PIN-FORMED (PIN) proteins to the carrier-mediated auxin efflux in Nicotiana tabacum L., cv. Bright Yellow (BY-2) tobacco cells. We show here that a majority of canonical NtPINs are transcribed in cultured cells and in planta. Cloning of NtPIN genes and their inducible overexpression in tobacco cells uncovered high auxin efflux activity of NtPIN11, accompanied by auxin starvation symptoms. Auxin transport parameters after NtPIN11 overexpression were further assessed using radiolabelled auxin accumulation and mathematical modelling. Unexpectedly, these experiments showed notable stimulation of auxin influx, which was accompanied by enhanced transcript levels of genes for a specific auxin influx carrier and by decreased transcript levels of other genes for auxin efflux carriers. A similar transcriptional response was observed upon removal of auxin from the culture medium, which resulted in decreased auxin efflux. Overall, our results revealed an auxin transport-based homeostatic mechanism for the maintenance of endogenous auxin levels. OPEN RESEARCH BADGES: This article has earned an Open Data Badge for making publicly available the digitally-shareable data necessary to reproduce the reported results. The data is available at http://osf.io/ka97b/.
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Affiliation(s)
- Karel Müller
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Petr Hošek
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Martina Laňková
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Stanislav Vosolsobě
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - Kateřina Malínská
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Mária Čarná
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Markéta Fílová
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Petre I Dobrev
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Michaela Helusová
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Klára Hoyerová
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Jan Petrášek
- The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojová 263, 165 02 Prague 6, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
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14
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Sauer M, Kleine-Vehn J. PIN-FORMED and PIN-LIKES auxin transport facilitators. Development 2019; 146:146/15/dev168088. [PMID: 31371525 DOI: 10.1242/dev.168088] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The phytohormone auxin influences virtually all aspects of plant growth and development. Auxin transport across membranes is facilitated by, among other proteins, members of the PIN-FORMED (PIN) and the structurally similar PIN-LIKES (PILS) families, which together govern directional cell-to-cell transport and intracellular accumulation of auxin. Canonical PIN proteins, which exhibit a polar localization in the plasma membrane, determine many patterning and directional growth responses. Conversely, the less-studied non-canonical PINs and PILS proteins, which mostly localize to the endoplasmic reticulum, attenuate cellular auxin responses. Here, and in the accompanying poster, we provide a brief summary of current knowledge of the structure, evolution, function and regulation of these auxin transport facilitators.
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Affiliation(s)
- Michael Sauer
- Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| | - Jürgen Kleine-Vehn
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences Vienna (BOKU), Muthgasse 18, 1190 Vienna, Austria
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15
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Zwiewka M, Bilanovičová V, Seifu YW, Nodzyński T. The Nuts and Bolts of PIN Auxin Efflux Carriers. FRONTIERS IN PLANT SCIENCE 2019; 10:985. [PMID: 31417597 PMCID: PMC6685051 DOI: 10.3389/fpls.2019.00985] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 07/12/2019] [Indexed: 05/20/2023]
Abstract
The plant-specific proteins named PIN-FORMED (PIN) efflux carriers facilitate the direction of auxin flow and thus play a vital role in the establishment of local auxin maxima within plant tissues that subsequently guide plant ontogenesis. They are membrane integral proteins with two hydrophobic regions consisting of alpha-helices linked with a hydrophilic loop, which is usually longer for the plasma membrane-localized PINs. The hydrophilic loop harbors molecular cues important for the subcellular localization and thus auxin efflux function of those transporters. The three-dimensional structure of PIN has not been solved yet. However, there are scattered but substantial data concerning the functional characterization of amino acid strings that constitute these carriers. These sequences include motifs vital for vesicular trafficking, residues regulating membrane diffusion, cellular polar localization, and activity of PINs. Here, we summarize those bits of information striving to provide a reference to structural motifs that have been investigated experimentally hoping to stimulate the efforts toward unraveling of PIN structure-function connections.
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Affiliation(s)
| | | | | | - Tomasz Nodzyński
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czechia
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Swarup R, Bhosale R. Developmental Roles of AUX1/LAX Auxin Influx Carriers in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:1306. [PMID: 31719828 PMCID: PMC6827439 DOI: 10.3389/fpls.2019.01306] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 09/19/2019] [Indexed: 05/06/2023]
Abstract
Plant hormone auxin regulates several aspects of plant growth and development. Auxin is predominantly synthesized in the shoot apex and developing leaf primordia and from there it is transported to the target tissues e.g. roots. Auxin transport is polar in nature and is carrier-mediated. AUXIN1/LIKE-AUX1 (AUX1/LAX) family members are the major auxin influx carriers whereas PIN-FORMED (PIN) family and some members of the P-GLYCOPROTEIN/ATP-BINDING CASSETTE B4 (PGP/ABCB) family are major auxin efflux carriers. AUX1/LAX auxin influx carriers are multi-membrane spanning transmembrane proteins sharing similarity to amino acid permeases. Mutations in AUX1/LAX genes result in auxin related developmental defects and have been implicated in regulating key plant processes including root and lateral root development, root gravitropism, root hair development, vascular patterning, seed germination, apical hook formation, leaf morphogenesis, phyllotactic patterning, female gametophyte development and embryo development. Recently AUX1 has also been implicated in regulating plant responses to abiotic stresses. This review summarizes our current understanding of the developmental roles of AUX1/LAX gene family and will also briefly discuss the modelling approaches that are providing new insight into the role of auxin transport in plant development.
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Affiliation(s)
- Ranjan Swarup
- Plant and Crop Sciences, School of Biosciences, University of Nottingham, Nottingham, United Kingdom
- Center for Plant Integrative Biology (CPIB), University of Nottingham, Nottingham, United Kingdom
- *Correspondence: Ranjan Swarup,
| | - Rahul Bhosale
- Plant and Crop Sciences, School of Biosciences, University of Nottingham, Nottingham, United Kingdom
- Center for Plant Integrative Biology (CPIB), University of Nottingham, Nottingham, United Kingdom
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