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Zheng L, Hu Y, Yang T, Wang Z, Wang D, Jia L, Xie Y, Luo L, Qi W, Lv Y, Beeckman T, Xuan W, Han Y. A root cap-localized NAC transcription factor controls root halotropic response to salt stress in Arabidopsis. Nat Commun 2024; 15:2061. [PMID: 38448433 PMCID: PMC10917740 DOI: 10.1038/s41467-024-46482-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 02/28/2024] [Indexed: 03/08/2024] Open
Abstract
Plants are capable of altering root growth direction to curtail exposure to a saline environment (termed halotropism). The root cap that surrounds root tip meristematic stem cells plays crucial roles in perceiving and responding to environmental stimuli. However, how the root cap mediates root halotropism remains undetermined. Here, we identified a root cap-localized NAC transcription factor, SOMBRERO (SMB), that is required for root halotropism. Its effect on root halotropism is attributable to the establishment of asymmetric auxin distribution in the lateral root cap (LRC) rather than to the alteration of cellular sodium equilibrium or amyloplast statoliths. Furthermore, SMB is essential for basal expression of the auxin influx carrier gene AUX1 in LRC and for auxin redistribution in a spatiotemporally-regulated manner, thereby leading to directional bending of roots away from higher salinity. Our findings uncover an SMB-AUX1-auxin module linking the role of the root cap to the activation of root halotropism.
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Affiliation(s)
- Lulu Zheng
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, Ghent, B-9052, Belgium
- VIB-UGent Center for Plant Systems Biology, Technologiepark 71, Ghent, B-9052, Belgium
| | - Yongfeng Hu
- Key Laboratory of Three Gorges Regional Plant Genetics and Germplasm Enhancement, Biotechnology Research Center, China Three Gorges University, Yichang, China
| | - Tianzhao Yang
- National Engineering Laboratory of Crop Stress Resistence Breeding, School of Life Sciences, Anhui Agricultural University, Hefei, 230036, China
| | - Zhen Wang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China
| | - Daoyuan Wang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China
| | - Letian Jia
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China
| | - Yuanming Xie
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China
| | - Long Luo
- National Engineering Laboratory of Crop Stress Resistence Breeding, School of Life Sciences, Anhui Agricultural University, Hefei, 230036, China
| | - Weicong Qi
- Excellence and Innovation Center, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China
| | - Yuanda Lv
- Excellence and Innovation Center, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China
| | - Tom Beeckman
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, Ghent, B-9052, Belgium
- VIB-UGent Center for Plant Systems Biology, Technologiepark 71, Ghent, B-9052, Belgium
| | - Wei Xuan
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics & Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China.
| | - Yi Han
- National Engineering Laboratory of Crop Stress Resistence Breeding, School of Life Sciences, Anhui Agricultural University, Hefei, 230036, China.
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2
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Dalal M, Mansi, Mayandi K. Zoom-in to molecular mechanisms underlying root growth and function under heterogeneous soil environment and abiotic stresses. PLANTA 2023; 258:108. [PMID: 37898971 DOI: 10.1007/s00425-023-04262-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 10/06/2023] [Indexed: 10/31/2023]
Abstract
MAIN CONCLUSION The review describes tissue-specific and non-cell autonomous molecular responses regulating the root system architecture and function in plants. Phenotypic plasticity of roots relies on specific molecular and tissue specific responses towards local and microscale heterogeneity in edaphic factors. Unlike gravitropism, hydrotropism in Arabidopsis is regulated by MIZU KUSSIE1 (MIZ1)-dependent asymmetric distribution of cytokinin and activation of Arabidopsis response regulators, ARR16 and ARR17 on the lower water potential side of the root leading to higher cell division and root bending. The cortex specific role of Abscisic acid (ABA)-activated SNF1-related protein kinase 2.2 (SnRK2.2) and MIZ1 in elongation zone is emerging for hydrotropic curvature. Halotropism involves clathrin-mediated internalization of PIN FORMED 2 (PIN2) proteins at the side facing higher salt concentration in the root tip, and ABA-activated SnRK2.6 mediated phosphorylation of cortical microtubule-associated protein Spiral2-like (SP2L) in the root transition zone, which results in anisotropic cell expansion and root bending away from higher salt. In hydropatterning, Indole-3-acetic acid 3 (IAA3) interacts with SUMOylated-ARF7 (Auxin response factor 7) and prevents expression of Lateral organ boundaries-domain 16 (LBD16) in air-side of the root, while on wet side of the root, IAA3 cannot repress the non-SUMOylated-ARF7 thereby leading to LBD16 expression and lateral root development. In root vasculature, ABA induces expression of microRNA165/microRNA166 in endodermis, which moves into the stele to target class III Homeodomain leucine zipper protein (HD-ZIP III) mRNA in non-cell autonomous manner. The bidirectional gradient of microRNA165/6 and HD-ZIP III mRNA regulates xylem patterning under stress. Understanding the tissue specific molecular mechanisms regulating the root responses under heterogeneous and stress environments will help in designing climate-resilient crops.
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Affiliation(s)
- Monika Dalal
- ICAR-National Institute for Plant Biotechnology, New Delhi, 110012, India.
| | - Mansi
- ICAR-National Institute for Plant Biotechnology, New Delhi, 110012, India
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK
| | - Karthikeyan Mayandi
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara, 630-0192, Japan
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3
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Tyagi A, Ali S, Park S, Bae H. Deciphering the role of mechanosensitive channels in plant root biology: perception, signaling, and adaptive responses. PLANTA 2023; 258:105. [PMID: 37878056 DOI: 10.1007/s00425-023-04261-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 10/02/2023] [Indexed: 10/26/2023]
Abstract
MAIN CONCLUSION Mechanosensitive channels are integral membrane proteins that rapidly translate extrinsic or intrinsic mechanical tensions into biological responses. They can serve as potential candidates for developing smart-resilient crops with efficient root systems. Mechanosensitive (MS) calcium channels are molecular switches for mechanoperception and signal transduction in all living organisms. Although tremendous progress has been made in understanding mechanoperception and signal transduction in bacteria and animals, this remains largely unknown in plants. However, identification and validation of MS channels such as Mid1-complementing activity channels (MCAs), mechanosensitive-like channels (MSLs), and Piezo channels (PIEZO) has been the most significant discovery in plant mechanobiology, providing novel insights into plant mechanoperception. This review summarizes recent advances in root mechanobiology, focusing on MS channels and their related signaling players, such as calcium ions (Ca2+), reactive oxygen species (ROS), and phytohormones. Despite significant advances in understanding the role of Ca2+ signaling in root biology, little is known about the involvement of MS channel-driven Ca2+ and ROS signaling. Additionally, the hotspots connecting the upstream and downstream signaling of MS channels remain unclear. In light of this, we discuss the present knowledge of MS channels in root biology and their role in root developmental and adaptive traits. We also provide a model highlighting upstream (cell wall sensors) and downstream signaling players, viz., Ca2+, ROS, and hormones, connected with MS channels. Furthermore, we highlighted the importance of emerging signaling molecules, such as nitric oxide (NO), hydrogen sulfide (H2S), and neurotransmitters (NTs), and their association with root mechanoperception. Finally, we conclude with future directions and knowledge gaps that warrant further research to decipher the complexity of root mechanosensing.
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Affiliation(s)
- Anshika Tyagi
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk, 38541, Republic of Korea.
| | - Sajad Ali
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk, 38541, Republic of Korea
| | - Suvin Park
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk, 38541, Republic of Korea
| | - Hanhong Bae
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk, 38541, Republic of Korea.
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4
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Kiradjiev KB, Band LR. Multiscale Asymptotic Analysis Reveals How Cell Growth and Subcellular Compartments Affect Tissue-Scale Hormone Transport. Bull Math Biol 2023; 85:101. [PMID: 37702758 PMCID: PMC10499980 DOI: 10.1007/s11538-023-01199-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 08/14/2023] [Indexed: 09/14/2023]
Abstract
Determining how cell-scale processes lead to tissue-scale patterns is key to understanding how hormones and morphogens are distributed within biological tissues and control developmental processes. In this article, we use multiscale asymptotic analysis to derive a continuum approximation for hormone transport in a long file of cells to determine how subcellular compartments and cell growth and division affect tissue-scale hormone transport. Focusing our study on plant tissues, we begin by presenting a discrete multicellular ODE model tracking the hormone concentration in each cell's cytoplasm, subcellular vacuole, and surrounding apoplast, represented by separate compartments in the cell-file geometry. We allow the cells to grow at a rate that can depend both on space and time, accounting for both cytoplasmic and vacuolar expansion. Multiscale asymptotic analysis enables us to systematically derive the corresponding continuum model, obtaining an effective reaction-advection-diffusion equation and revealing how the effective diffusivity, effective advective velocity, and the effective sink term depend on the parameters in the cell-scale model. The continuum approximation reveals how subcellular compartments, such as vacuoles, can act as storage vessels, that significantly alter the effective properties of hormone transport, such as the effective diffusivity and the induced effective velocity. Furthermore, we show how cell growth and spatial variance across cell lengths affect the effective diffusivity and the induced effective velocity, and how these affect the tissue-scale hormone distribution. In particular, we find that cell growth naturally induces an effective velocity in the direction of growth, whereas spatial variance across cell lengths induces effective velocity due to the presence of an extra compartment, such as the apoplast and the vacuole, and variations in the relative sizes between the compartments across the file of cells. It is revealed that hormone transport is faster across cells of decreasing lengths than cells with increasing lengths. We also investigate the effect of cell division on transport dynamics, assuming that each cell divides as soon as it doubles in size, and find that increasing the time between successive cell divisions decreases the growth rate, which enhances the effect of cell division in slowing hormone transport. Motivated by recent experimental discoveries, we discuss particular applications for transport of gibberellic acid (GA), an important growth hormone, within the Arabidopsis root. The model reveals precisely how membrane proteins that mediate facilitated GA transport affect the effective tissue-scale transport. However, the results are general enough to be relevant to other plant hormones, or other substances that are transported in a similar way in any type of cells.
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Affiliation(s)
- K B Kiradjiev
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
| | - L R Band
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
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5
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Li H, Duijts K, Pasini C, van Santen JE, Lamers J, de Zeeuw T, Verstappen F, Wang N, Zeeman SC, Santelia D, Zhang Y, Testerink C. Effective root responses to salinity stress include maintained cell expansion and carbon allocation. THE NEW PHYTOLOGIST 2023; 238:1942-1956. [PMID: 36908088 DOI: 10.1111/nph.18873] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 02/25/2023] [Indexed: 05/04/2023]
Abstract
Acclimation of root growth is vital for plants to survive salt stress. Halophytes are great examples of plants that thrive even under severe salinity, but their salt tolerance mechanisms, especially those mediated by root responses, are still largely unknown. We compared root growth responses of the halophyte Schrenkiella parvula with its glycophytic relative species Arabidopsis thaliana under salt stress and performed transcriptomic analysis of S. parvula roots to identify possible gene regulatory networks underlying their physiological responses. Schrenkiella parvula roots do not avoid salt and experience less growth inhibition under salt stress. Salt-induced abscisic acid levels were higher in S. parvula roots compared with Arabidopsis. Root transcriptomic analysis of S. parvula revealed the induction of sugar transporters and genes regulating cell expansion and suberization under salt stress. 14 C-labeled carbon partitioning analyses showed that S. parvula continued allocating carbon to roots from shoots under salt stress while carbon barely allocated to Arabidopsis roots. Further physiological investigation revealed that S. parvula roots maintained root cell expansion and enhanced suberization under severe salt stress. In summary, roots of S. parvula deploy multiple physiological and developmental adjustments under salt stress to maintain growth, providing new avenues to improve salt tolerance of plants using root-specific strategies.
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Affiliation(s)
- Hongfei Li
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
| | - Kilian Duijts
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
| | - Carlo Pasini
- Institute of Integrative Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Joyce E van Santen
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
| | - Jasper Lamers
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
| | - Thijs de Zeeuw
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
| | - Francel Verstappen
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
| | - Nan Wang
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
| | - Samuel C Zeeman
- Institute of Molecular Plant Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Diana Santelia
- Institute of Integrative Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Yanxia Zhang
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
| | - Christa Testerink
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University & Research, 6708PB, Wageningen, the Netherlands
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6
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Shelden MC, Munns R. Crop root system plasticity for improved yields in saline soils. FRONTIERS IN PLANT SCIENCE 2023; 14:1120583. [PMID: 36909408 PMCID: PMC9999379 DOI: 10.3389/fpls.2023.1120583] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
Crop yields must increase to meet the demands of a growing world population. Soil salinization is increasing due to the impacts of climate change, reducing the area of arable land for crop production. Plant root systems are plastic, and their architecture can be modulated to (1) acquire nutrients and water for growth, and (2) respond to hostile soil environments. Saline soils inhibit primary root growth and alter root system architecture (RSA) of crop plants. In this review, we explore how crop root systems respond and adapt to salinity, focusing predominately on the staple cereal crops wheat, maize, rice, and barley, that all play a major role in global food security. Cereal crops are classified as glycophytes (salt-sensitive) however salt-tolerance can differ both between species and within a species. In the past, due to the inherent difficulties associated with visualising and measuring root traits, crop breeding strategies have tended to focus on optimising shoot traits. High-resolution phenotyping techniques now make it possible to visualise and measure root traits in soil systems. A steep, deep and cheap root ideotype has been proposed for water and nitrogen capture. Changes in RSA can be an adaptive strategy to avoid saline soils whilst optimising nutrient and water acquisition. In this review we propose a new model for designing crops with a salt-tolerant root ideotype. The proposed root ideotype would exhibit root plasticity to adapt to saline soils, root anatomical changes to conserve energy and restrict sodium (Na+) uptake, and transport mechanisms to reduce the amount of Na+ transported to leaves. In the future, combining high-resolution root phenotyping with advances in crop genetics will allow us to uncover root traits in complex crop species such as wheat, that can be incorporated into crop breeding programs for yield stability in saline soils.
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Affiliation(s)
- Megan C. Shelden
- School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, SA, Australia
| | - Rana Munns
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, University of Western Australia, Crawley, WA, Australia
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7
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Santos Teixeira J, van den Berg T, ten Tusscher K. Complementary roles for auxin and auxin signalling revealed by reverse engineering lateral root stable prebranch site formation. Development 2022; 149:279332. [PMID: 36314783 PMCID: PMC9793420 DOI: 10.1242/dev.200927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/24/2022] [Indexed: 11/22/2022]
Abstract
Priming is the process through which periodic elevations in auxin signalling prepattern future sites for lateral root formation, called prebranch sites. Thus far, the extent to which elevations in auxin concentration and/or auxin signalling are required for priming and prebranch site formation has remained a matter of debate. Recently, we discovered a reflux-and-growth mechanism for priming generating periodic elevations in auxin concentration that subsequently dissipate. Here, we reverse engineer a mechanism for prebranch site formation that translates these transient elevations into a persistent increase in auxin signalling, resolving the prior debate into a two-step process of auxin concentration-mediated initial signal and auxin signalling capacity-mediated memorization. A crucial aspect of the prebranch site formation mechanism is its activation in response to time-integrated rather than instantaneous auxin signalling. The proposed mechanism is demonstrated to be consistent with prebranch site auxin signalling dynamics, lateral inhibition, and symmetry-breaking mechanisms and perturbations in auxin homeostasis.
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Affiliation(s)
- Joana Santos Teixeira
- Computational Developmental Biology Group, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Thea van den Berg
- Computational Developmental Biology Group, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Kirsten ten Tusscher
- Computational Developmental Biology Group, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands,Author for correspondence ()
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8
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Gigli-Bisceglia N, van Zelm E, Huo W, Lamers J, Testerink C. Arabidopsis root responses to salinity depend on pectin modification and cell wall sensing. Development 2022; 149:275422. [PMID: 35574987 PMCID: PMC9270968 DOI: 10.1242/dev.200363] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 04/29/2022] [Indexed: 12/21/2022]
Abstract
Owing to its detrimental effect on plant growth, salinity is an increasing worldwide problem for agriculture. To understand the molecular mechanisms activated in response to salt in Arabidopsis thaliana, we investigated the Catharanthus roseus receptor-like kinase 1-like family, which contains sensors that were previously shown to be involved in sensing the structural integrity of the cell walls. We found that herk1 the1-4 double mutants, lacking the function of HERKULES1 (HERK1) and combined with a gain-of-function allele of THESEUS1 (THE1), strongly respond to salt application, resulting in an intense activation of stress responses, similarly to plants lacking FERONIA (FER) function. We report that salt triggers pectin methyl esterase (PME) activation and show its requirement for the activation of several salt-dependent responses. Because chemical inhibition of PMEs alleviates these salt-induced responses, we hypothesize a model in which salt directly leads to cell wall modifications through the activation of PMEs. Responses to salt partly require the functionality of FER alone or HERK1/THE1 to attenuate salt effects, highlighting the complexity of the salt-sensing mechanisms that rely on cell wall integrity. Summary: Salt-triggered activation of pectin methyl esterase changes pectin in Arabidopsis, inducing at least two pathways: a CrRLK1L-dependent pathway downregulating salt stress responses and a CrRLK1L-independent pathway that activates downstream signaling.
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Affiliation(s)
- Nora Gigli-Bisceglia
- Laboratory of Plant Physiology, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Eva van Zelm
- Laboratory of Plant Physiology, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Wenying Huo
- Laboratory of Plant Physiology, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Jasper Lamers
- Laboratory of Plant Physiology, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Christa Testerink
- Laboratory of Plant Physiology, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
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9
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Mellor NL, Voß U, Ware A, Janes G, Barrack D, Bishopp A, Bennett MJ, Geisler M, Wells DM, Band LR. Systems approaches reveal that ABCB and PIN proteins mediate co-dependent auxin efflux. THE PLANT CELL 2022; 34:2309-2327. [PMID: 35302640 PMCID: PMC9134068 DOI: 10.1093/plcell/koac086] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/10/2022] [Indexed: 05/11/2023]
Abstract
Members of the B family of membrane-bound ATP-binding cassette (ABC) transporters represent key components of the auxin efflux machinery in plants. Over the last two decades, experimental studies have shown that modifying ATP-binding cassette sub-family B (ABCB) expression affects auxin distribution and plant phenotypes. However, precisely how ABCB proteins transport auxin in conjunction with the more widely studied family of PIN-formed (PIN) auxin efflux transporters is unclear, and studies using heterologous systems have produced conflicting results. Here, we integrate ABCB localization data into a multicellular model of auxin transport in the Arabidopsis thaliana root tip to predict how ABCB-mediated auxin transport impacts organ-scale auxin distribution. We use our model to test five potential ABCB-PIN regulatory interactions, simulating the auxin dynamics for each interaction and quantitatively comparing the predictions with experimental images of the DII-VENUS auxin reporter in wild-type and abcb single and double loss-of-function mutants. Only specific ABCB-PIN regulatory interactions result in predictions that recreate the experimentally observed DII-VENUS distributions and long-distance auxin transport. Our results suggest that ABCBs enable auxin efflux independently of PINs; however, PIN-mediated auxin efflux is predominantly through a co-dependent efflux where co-localized with ABCBs.
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Affiliation(s)
| | | | - Alexander Ware
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
| | - George Janes
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
| | - Duncan Barrack
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
| | - Anthony Bishopp
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
| | - Malcolm J Bennett
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
| | - Markus Geisler
- Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland
| | - Darren M Wells
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
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10
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Zou Y, Zhang Y, Testerink C. Root dynamic growth strategies in response to salinity. PLANT, CELL & ENVIRONMENT 2022; 45:695-704. [PMID: 34716934 PMCID: PMC9298695 DOI: 10.1111/pce.14205] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/17/2021] [Accepted: 10/09/2021] [Indexed: 05/25/2023]
Abstract
Increasing soil salinization largely impacts crop yield worldwide. To deal with salinity stress, plants exhibit an array of responses, including root system architecture remodelling. Here, we review recent progress in physiological, developmental and cellular mechanisms of root growth responses to salinity. Most recent research in modulation of root branching, root tropisms, as well as in root cell wall modifications under salinity stress, is discussed in the context of the contribution of these responses to overall plant performance. We highlight the power of natural variation approaches revealing novel potential pathways responsible for differences in root salt stress responses. Together, these new findings promote our understanding of how salt shapes the root phenotype, which may provide potential avenues for engineering crops with better yield and survival in saline soils.
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Affiliation(s)
- Yutao Zou
- Laboratory of Plant Physiology, Plant Sciences GroupWageningen University and ResearchWageningenthe Netherlands
| | - Yanxia Zhang
- Laboratory of Plant Physiology, Plant Sciences GroupWageningen University and ResearchWageningenthe Netherlands
| | - Christa Testerink
- Laboratory of Plant Physiology, Plant Sciences GroupWageningen University and ResearchWageningenthe Netherlands
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11
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Cackett L, Cannistraci CV, Meier S, Ferrandi P, Pěnčík A, Gehring C, Novák O, Ingle RA, Donaldson L. Salt-Specific Gene Expression Reveals Elevated Auxin Levels in Arabidopsis thaliana Plants Grown Under Saline Conditions. FRONTIERS IN PLANT SCIENCE 2022; 13:804716. [PMID: 35222469 PMCID: PMC8866861 DOI: 10.3389/fpls.2022.804716] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 01/03/2022] [Indexed: 06/14/2023]
Abstract
Soil salinization is increasing globally, driving a reduction in crop yields that threatens food security. Salinity stress reduces plant growth by exerting two stresses on plants: rapid shoot ion-independent effects which are largely osmotic and delayed ionic effects that are specific to salinity stress. In this study we set out to delineate the osmotic from the ionic effects of salinity stress. Arabidopsis thaliana plants were germinated and grown for two weeks in media supplemented with 50, 75, 100, or 125 mM NaCl (that imposes both an ionic and osmotic stress) or iso-osmolar concentrations (100, 150, 200, or 250 mM) of sorbitol, that imposes only an osmotic stress. A subsequent transcriptional analysis was performed to identify sets of genes that are differentially expressed in plants grown in (1) NaCl or (2) sorbitol compared to controls. A comparison of the gene sets identified genes that are differentially expressed under both challenge conditions (osmotic genes) and genes that are only differentially expressed in plants grown on NaCl (ionic genes, hereafter referred to as salt-specific genes). A pathway analysis of the osmotic and salt-specific gene lists revealed that distinct biological processes are modulated during growth under the two conditions. The list of salt-specific genes was enriched in the gene ontology (GO) term "response to auxin." Quantification of the predominant auxin, indole-3-acetic acid (IAA) and IAA biosynthetic intermediates revealed that IAA levels are elevated in a salt-specific manner through increased IAA biosynthesis. Furthermore, the expression of NITRILASE 2 (NIT2), which hydrolyses indole-3-acetonitile (IAN) into IAA, increased in a salt-specific manner. Overexpression of NIT2 resulted in increased IAA levels, improved Na:K ratios and enhanced survival and growth of Arabidopsis under saline conditions. Overall, our data suggest that auxin is involved in maintaining growth during the ionic stress imposed by saline conditions.
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Affiliation(s)
- Lee Cackett
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, South Africa
| | - Carlo Vittorio Cannistraci
- Center for Complex Network Intelligence, Tsinghua Laboratory of Brain and Intelligence, Department of Computer Science, Tsinghua University, Beijing, China
- Center for Complex Network Intelligence, Tsinghua Laboratory of Brain and Intelligence, Department of Biomedical Engineering, Tsinghua University, Beijing, China
- Center for Systems Biology Dresden (CSBD), Dresden, Germany
| | - Stuart Meier
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, South Africa
| | - Paul Ferrandi
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, South Africa
- International Centre for Genetic Engineering and Biotechnology, Cape Town, South Africa
| | - Aleš Pěnčík
- Laboratory of Growth Regulators, Institute of Experimental Botany of the Czech Academy of Sciences and Faculty of Science of Palacký University, Olomouc, Czechia
| | - Chris Gehring
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Ondřej Novák
- Laboratory of Growth Regulators, Institute of Experimental Botany of the Czech Academy of Sciences and Faculty of Science of Palacký University, Olomouc, Czechia
| | - Robert A. Ingle
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, South Africa
| | - Lara Donaldson
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, South Africa
- International Centre for Genetic Engineering and Biotechnology, Cape Town, South Africa
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12
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Rutten J, van den Berg T, Tusscher KT. Modeling Auxin Signaling in Roots: Auxin Computations. Cold Spring Harb Perspect Biol 2022; 14:a040089. [PMID: 34001532 PMCID: PMC8805645 DOI: 10.1101/cshperspect.a040089] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Auxin signaling and patterning is an inherently complex process, involving polarized auxin transport, metabolism, and signaling, its effect on developmental zones, as well as growth rates, and the feedback between all these different aspects. This complexity has led to an important role for computational modeling in unraveling the multifactorial roles of auxin in plant developmental and adaptive processes. Here we discuss the basic ingredients of auxin signaling and patterning models for root development as well as a series of key modeling studies in this area. These modeling studies have helped elucidate how plants use auxin signaling to compute the size of their root meristem, the direction in which to grow, and when and where to form lateral roots. Importantly, these models highlight how auxin, through patterning of and collaborating with other factors, can fulfill all these roles simultaneously.
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Affiliation(s)
- Jaap Rutten
- Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Thea van den Berg
- Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Kirsten Ten Tusscher
- Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands
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13
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Zhang X, Han C, Liang Y, Yang Y, Liu Y, Cao Y. Combined full-length transcriptomic and metabolomic analysis reveals the regulatory mechanisms of adaptation to salt stress in asparagus. FRONTIERS IN PLANT SCIENCE 2022; 13:1050840. [PMID: 36388563 PMCID: PMC9648818 DOI: 10.3389/fpls.2022.1050840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 10/14/2022] [Indexed: 05/10/2023]
Abstract
Soil salinity is a very serious abiotic stressor that affects plant growth and threatens crop yield. Thus, it is important to explore the mechanisms of salt tolerance of plant and then to stabilize and improve crop yield. Asparagus is an important cash crop, but its salt tolerance mechanisms are largely unknown. Full-length transcriptomic and metabolomic analyses were performed on two asparagus genotypes: 'jx1502' (a salt-tolerant genotype) and 'gold crown' (a salt-sensitive genotype). Compared with the distilled water treatment (control), 877 and 1610 differentially expressed genes (DEGs) were identified in 'jx1502' and 'gold crown' under salt stress treatment, respectively, and 135 and 73 differentially accumulated metabolites (DAMs) were identified in 'jx1502' and 'gold crown' under salt stress treatment, respectively. DEGs related to ion transport, plant hormone response, and cell division and growth presented differential expression profiles between 'jx1502' and 'gold crown.' In 'jx1502,' 11 ion transport-related DEGs, 8 plant hormone response-related DEGs, and 12 cell division and growth-related DEGs were upregulated, while 7 ion transport-related DEGs, 4 plant hormone response-related DEGs, and 2 cell division and growth-related DEGs were downregulated. Interestingly, in 'gold crown,' 14 ion transport-related DEGs, 2 plant hormone response-related DEGs, and 6 cell division and growth-related DEGs were upregulated, while 45 ion transport-related DEGs, 13 plant hormone response-related DEGs, and 16 cell division and growth-related DEGs were downregulated. Genotype 'jx1502' can modulate K+/Na+ and water homeostasis and maintain a more constant transport system for nutrient uptake and distribution than 'gold crown' under salt stress. Genotype 'jx1502' strengthened the response to auxin (IAA), as well as cell division and growth for root remodeling and thus salt tolerance. Therefore, the integration analysis of transcriptomic and metabolomic indicated that 'jx1502' enhanced sugar and amino acid metabolism for energy supply and osmotic regulatory substance accumulation to meet the demands of protective mechanisms against salt stress. This work contributed to reveal the underlying salt tolerance mechanism of asparagus at transcription and metabolism level and proposed new directions for asparagus variety improvement.
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Affiliation(s)
- Xuhong Zhang
- Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, China
- Landscape Management and Protection Center, Shijiazhuang Bureau of Landscape Architecture, Shijiazhuang, China
| | - Changzhi Han
- College of Biodiversity Conservation, Southwest Forestry University, Kunming, China
| | - Yuqin Liang
- Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, China
| | - Yang Yang
- Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, China
| | - Yun Liu
- Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, China
| | - Yanpo Cao
- Institute of Cash Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, China
- *Correspondence: Yanpo Cao,
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14
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van Schijndel L, Snoek BL, ten Tusscher K. Embodiment in distributed information processing: "Solid" plants versus "liquid" ant colonies. QUANTITATIVE PLANT BIOLOGY 2022; 3:e27. [PMID: 37077985 PMCID: PMC10095861 DOI: 10.1017/qpb.2022.22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/31/2022] [Accepted: 11/02/2022] [Indexed: 05/02/2023]
Abstract
Information processing is an essential part of biology, enabling coordination of intra-organismal processes such as development, environmental adaptation and inter-organismal communication. Whilst in animals with specialised brain tissue a substantial amount of information processing occurs in a centralised manner, most biological computing is distributed across multiple entities, such as cells in a tissue, roots in a root system or ants in a colony. Physical context, called embodiment, also affects the nature of biological computing. While plants and ant colonies both perform distributed computing, in plants the units occupy fixed positions while individual ants move around. This distinction, solid versus liquid brain computing, shapes the nature of computations. Here we compare information processing in plants and ant colonies, highlighting how similarities and differences originate in, as well as make use of, the differences in embodiment. We end with a discussion on how this embodiment perspective may inform the debate on plant cognition.
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Affiliation(s)
- Laura van Schijndel
- Laboratory of Genetics, Department of Plant Sciences, Wageningen University, Wageningen, The Netherlands
| | - Basten L. Snoek
- Bioinformatics Group, Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Kirsten ten Tusscher
- Computational Developmental Biology Group, Department of Biology, Utrecht University, Utrecht, The Netherlands
- Author for correspondence: K. ten Tusscher, E-mail:
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15
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Collis H, Band LR, Fozard JA, Ghetiu T, Wilson MH, Mellor NL, Bennett MJ, Owen MR. The Virtual Root : Mathematical Modeling of Auxin Transport in the Arabidopsis Root Tip Using the Open-Source Software SimuPlant. Methods Mol Biol 2022; 2395:147-164. [PMID: 34822153 DOI: 10.1007/978-1-0716-1816-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Hormone signals like auxin play a critical role controlling plant growth and development. Determining the mechanisms that regulate auxin distribution in cells and tissues is a vital step in understanding this hormone's role during plant development. Recent mathematical models have enabled us to understand the essential role that auxin influx and efflux carriers play in auxin transport in the Arabidopsis root tip (Band et al., Plant Cell 26(3):862-875, 2014; Grieneisen et al., Nature 449(7165):1008-1013, 2007; van den Berg et al., Development 143(18):3350-3362, 2016). In this chapter, we describe SimuPlant: The Virtual Root (SimuPlant, University of Nottingham. https://www.simuplant.org/ . Accessed 20 Sept 2019); an open source software suite, built using the OpenAlea (Pradal et al., Funct Plant Biol 35(10):751-760, 2008) framework, that is designed to simulate vertex-based models in real plant tissue geometries. We provide guidance on how to install SimuPlant, run 2D auxin transport models in the Arabidopsis root tip, manipulate parameters, and visualize model outputs.SimuPlant features a graphical user interface (GUI) designed to allow users with no programming experience to simulate auxin dynamics within the Arabidopsis root tip. Within the user interface, users of SimuPlant can select from a range of model assumptions and can choose to manipulate model and simulation parameter values. Users can then investigate how their choices affect the predicted distribution of auxin in the Arabidopsis root tip. The results of the model simulations are shown visually within the root geometry and can be exported and saved as PNG image files.
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Affiliation(s)
- Heather Collis
- School of Mathematical Sciences, University of Nottingham, Nottingham, UK
| | - Leah R Band
- School of Mathematical Sciences, University of Nottingham, Nottingham, UK.
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Nottingham, UK.
| | - John A Fozard
- Department of Computational and Systems Biology, John Innes Centre, Norwich Research Park, Norwich, UK
| | | | - Michael H Wilson
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Nottingham, UK
| | - Nathan L Mellor
- Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Nottingham, UK
| | - Malcolm J Bennett
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Nottingham, UK
| | - Markus R Owen
- School of Mathematical Sciences, University of Nottingham, Nottingham, UK
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16
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Kościelniak P, Glazińska P, Kȩsy J, Zadworny M. Formation and Development of Taproots in Deciduous Tree Species. FRONTIERS IN PLANT SCIENCE 2021; 12:772567. [PMID: 34925417 PMCID: PMC8675582 DOI: 10.3389/fpls.2021.772567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/27/2021] [Indexed: 06/14/2023]
Abstract
Trees are generally long-lived and are therefore exposed to numerous episodes of external stimuli and adverse environmental conditions. In certain trees e.g., oaks, taproots evolved to increase the tree's ability to acquire water from deeper soil layers. Despite the significant role of taproots, little is known about the growth regulation through internal factors (genes, phytohormones, and micro-RNAs), regulating taproot formation and growth, or the effect of external factors, e.g., drought. The interaction of internal and external stimuli, involving complex signaling pathways, regulates taproot growth during tip formation and the regulation of cell division in the root apical meristem (RAM). Assuming that the RAM is the primary regulatory center responsible for taproot growth, factors affecting the RAM function provide fundamental information on the mechanisms affecting taproot development.
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Affiliation(s)
| | - Paulina Glazińska
- Department of Plant Physiology and Biotechnology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Toruń, Poland
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Toruń, Poland
| | - Jacek Kȩsy
- Department of Plant Physiology and Biotechnology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Toruń, Poland
| | - Marcin Zadworny
- Institute of Dendrology, Polish Academy of Sciences, Kórnik, Poland
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17
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Adaptive divergence in shoot gravitropism creates hybrid sterility in an Australian wildflower. Proc Natl Acad Sci U S A 2021; 118:2004901118. [PMID: 34789571 PMCID: PMC8617494 DOI: 10.1073/pnas.2004901118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2021] [Indexed: 11/18/2022] Open
Abstract
New species originate as populations become reproductively isolated from one another. Despite recent progress in uncovering the genetic basis of reproductive isolation, it remains unclear whether intrinsic reproductive barriers, such as hybrid sterility, can evolve as a by-product of local adaptation to contrasting environments. Here, we show that differences in a plant’s response to the pull of gravity have repeatedly evolved amongst coastal populations of an Australian wildflower, thus implicating a role of natural selection in their evolution. We found a strong genetic association between variation in this adaptive trait and hybrid sterility, suggesting that intrinsic reproductive barriers contribute to the origin of new species as populations adapt to heterogeneous environments. Natural selection is responsible for much of the diversity we see in nature. Just as it drives the evolution of new traits, it can also lead to new species. However, it is unclear whether natural selection conferring adaptation to local environments can drive speciation through the evolution of hybrid sterility between populations. Here, we show that adaptive divergence in shoot gravitropism, the ability of a plant’s shoot to bend upwards in response to the downward pull of gravity, contributes to the evolution of hybrid sterility in an Australian wildflower, Senecio lautus. We find that shoot gravitropism has evolved multiple times in association with plant height between adjacent populations inhabiting contrasting environments, suggesting that these traits have evolved by natural selection. We directly tested this prediction using a hybrid population subjected to eight rounds of recombination and three rounds of selection in the field. Our experiments revealed that shoot gravitropism responds to natural selection in the expected direction of the locally adapted population. Using the advanced hybrid population, we discovered that individuals with extreme differences in gravitropism had more sterile crosses than individuals with similar gravitropic responses, which were largely fertile, indicating that this adaptive trait is genetically correlated with hybrid sterility. Our results suggest that natural selection can drive the evolution of locally adaptive traits that also create hybrid sterility, thus revealing an evolutionary connection between local adaptation and the origin of new species.
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18
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Karlova R, Boer D, Hayes S, Testerink C. Root plasticity under abiotic stress. PLANT PHYSIOLOGY 2021; 187:1057-1070. [PMID: 34734279 PMCID: PMC8566202 DOI: 10.1093/plphys/kiab392] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/25/2021] [Indexed: 05/08/2023]
Abstract
Abiotic stresses increasingly threaten existing ecological and agricultural systems across the globe. Plant roots perceive these stresses in the soil and adapt their architecture accordingly. This review provides insights into recent discoveries showing the importance of root system architecture (RSA) and plasticity for the survival and development of plants under heat, cold, drought, salt, and flooding stress. In addition, we review the molecular regulation and hormonal pathways involved in controlling RSA plasticity, main root growth, branching and lateral root growth, root hair development, and formation of adventitious roots. Several stresses affect root anatomy by causing aerenchyma formation, lignin and suberin deposition, and Casparian strip modulation. Roots can also actively grow toward favorable soil conditions and avoid environments detrimental to their development. Recent advances in understanding the cellular mechanisms behind these different root tropisms are discussed. Understanding root plasticity will be instrumental for the development of crops that are resilient in the face of abiotic stress.
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Affiliation(s)
- Rumyana Karlova
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Damian Boer
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Scott Hayes
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Christa Testerink
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Author for communication:
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19
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Methods to Quantify Cell Division and Hormone Gradients During Root Tropisms. Methods Mol Biol 2021. [PMID: 34647249 DOI: 10.1007/978-1-0716-1677-2_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Tropisms are growth-based plant directional movements, allowing plants to respond to their living environments. Plant roots have developed various tropic responses, including gravitropism, hydrotropism, chemotropism, and halotropism, in response to the gravity, moisture gradient, nutrient gradient, and salinity gradient, respectively. Revealed mechanisms of several tropic responses suggested that plant hormone gradient and cell division activity play key roles in determining these responses. Approaches to measure cell division and hormone gradients, however, have rarely been applied in root tropic analyses. Here, we describe a number of methods to quantify cell division and hormone gradients during root tropic analysis. These approaches are mainly based on our previous researches on root hydrotropism.
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20
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Rutten JP, Ten Tusscher KH. Bootstrapping and Pinning down the Root Meristem; the Auxin-PLT-ARR Network Unites Robustness and Sensitivity in Meristem Growth Control. Int J Mol Sci 2021; 22:ijms22094731. [PMID: 33946960 PMCID: PMC8125115 DOI: 10.3390/ijms22094731] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/19/2021] [Accepted: 04/27/2021] [Indexed: 12/26/2022] Open
Abstract
After germination, the meristem of the embryonic plant root becomes activated, expands in size and subsequently stabilizes to support post-embryonic root growth. The plant hormones auxin and cytokinin, together with master transcription factors of the PLETHORA (PLT) family have been shown to form a regulatory network that governs the patterning of this root meristem. Still, which functional constraints contributed to shaping the dynamics and architecture of this network, has largely remained unanswered. Using a combination of modeling approaches we reveal how the interplay between auxin and PLTs enables meristem activation in response to above-threshold stimulation, while its embedding in a PIN-mediated auxin reflux loop ensures localized PLT transcription and thereby, a finite meristem size. We furthermore demonstrate how this constrained PLT transcriptional domain enables independent control of meristem size and division rates, further supporting a division of labor between auxin and PLT. We subsequently reveal how the weaker auxin antagonism of the earlier active Arabidopsis response regulator 12 (ARR12) may arise from the absence of a DELLA protein interaction domain. Our model indicates that this reduced strength is essential to prevent collapse in the early stages of meristem expansion while at later stages the enhanced strength of Arabidopsis response regulator 1 (ARR1) is required for sufficient meristem size control. Summarizing, our work indicates that functional constraints significantly contribute to shaping the auxin-cytokinin-PLT regulatory network.
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21
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Stasko AK, Batnini A, Bolanos-Carriel C, Lin JE, Lin Y, Blakeslee JJ, Dorrance AE. Auxin Profiling and GmPIN Expression in Phytophthora sojae-Soybean Root Interactions. PHYTOPATHOLOGY 2020; 110:1988-2002. [PMID: 32602813 DOI: 10.1094/phyto-02-20-0046-r] [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] [Indexed: 06/11/2023]
Abstract
Auxin (indole-3-acetic acid, IAA) has been implicated as a susceptibility factor in both beneficial and pathogenic molecular plant-microbe interactions. Previous studies have identified a large number of auxin-related genes underlying quantitative disease resistance loci (QDRLs) for Phytophthora sojae. Thus, we hypothesized that auxin may be involved the P. sojae-soybean interaction. The levels of IAA and related metabolites were measured in mycelia and media supernatant as well as in mock and inoculated soybean roots in a time course assay. The expression of 11 soybean Pin-formed (GmPIN) auxin efflux transporter genes was also examined. Tryptophan, an auxin precursor, was detected in the P. sojae mycelia and media supernatant. During colonization of roots, levels of IAA and related metabolites were significantly higher in both moderately resistant Conrad and moderately susceptible Sloan inoculated roots compared with mock controls at 48 h postinoculation (hpi) in one experiment and at 72 hpi in a second, with Sloan accumulating higher levels of the auxin catabolite IAA-Ala than Conrad. Additionally, one GmPIN at 24 hpi, one at 48 hpi, and three at 72 hpi had higher expression in inoculated compared with the mock control roots in Conrad. The ability of resistant cultivars to cope with auxin accumulation may play an important role in quantitative disease resistance. Levels of jasmonic acid (JA), another plant hormone associated with defense responses, were also higher in inoculated roots at these same time points, suggesting that JA also plays a role during the later stages of infection.
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Affiliation(s)
- Anna K Stasko
- Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
- Center for Soybean Research, The Ohio State University, Wooster, OH 44691
| | - Amine Batnini
- Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
- Center for Soybean Research, The Ohio State University, Wooster, OH 44691
| | - Carlos Bolanos-Carriel
- Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
- Center for Soybean Research, The Ohio State University, Wooster, OH 44691
| | - Jinshan Ella Lin
- Department of Horticulture and Crop Science and OARDC Metabolite Analysis Cluster, The Ohio State University, Wooster, OH 44691
| | - Yun Lin
- Department of Horticulture and Crop Science and OARDC Metabolite Analysis Cluster, The Ohio State University, Wooster, OH 44691
| | - Joshua J Blakeslee
- Department of Horticulture and Crop Science and OARDC Metabolite Analysis Cluster, The Ohio State University, Wooster, OH 44691
- Center for Applied Plant Sciences, The Ohio State University, Columbus, OH 43210
| | - Anne E Dorrance
- Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
- Center for Soybean Research, The Ohio State University, Wooster, OH 44691
- Center for Applied Plant Sciences, The Ohio State University, Columbus, OH 43210
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22
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Szepesi Á. Halotropism: Phytohormonal Aspects and Potential Applications. FRONTIERS IN PLANT SCIENCE 2020; 11:571025. [PMID: 33042187 PMCID: PMC7527526 DOI: 10.3389/fpls.2020.571025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 09/02/2020] [Indexed: 05/15/2023]
Abstract
Halotropism is a sodium specific tropic movement of roots in order to obtain the optimal salt concentration for proper growth and development. Numerous results suggest that halotropic events are under the control and regulation of complex plant hormone pathway. This minireview collects some recent evidences about sodium sensing during halotropism and the hormonal regulation of halotropic responses in glycophytes. The precise hormonal mechanisms by which halophytes plant roots perceive salt stress and translate this perception into adaptive, directional growth forward increased salt concentrations are not well understood. This minireview aims to gather recently deciphered information about halotropism focusing potential hormonal aspects both in glycophytes and halophytes. Advances in our understanding of halotropic responses in different plant species could help these plants to be used for sustainable agriculture and other future applications.
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Affiliation(s)
- Ágnes Szepesi
- Department of Plant Biology, Institute of Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
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23
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Ribba T, Garrido-Vargas F, O'Brien JA. Auxin-mediated responses under salt stress: from developmental regulation to biotechnological applications. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3843-3853. [PMID: 32433743 DOI: 10.1093/jxb/eraa241] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 05/18/2020] [Indexed: 05/10/2023]
Abstract
As sessile organisms, plants are exposed to multiple abiotic stresses commonly found in nature. To survive, plants have developed complex responses that involve genetic, epigenetic, cellular, and morphological modifications. Among different environmental cues, salt stress has emerged as a critical problem contributing to yield losses and marked reductions in crop production. Moreover, as the climate changes, it is expected that salt stress will have a significant impact on crop production in the agroindustry. On a mechanistic level, salt stress is known to be regulated by the crosstalk of many signaling molecules such as phytohormones, with auxin having been described as a key mediator of the process. Auxin plays an important role in plant developmental responses and stress, modulating a complex balance of biosynthesis, transport, and signaling that among other things, finely tune physiological changes in plant architecture and Na+ accumulation. In this review, we describe current knowledge on auxin's role in modulating the salt stress response. We also discuss recent and potential biotechnological approaches to tackling salt stress.
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Affiliation(s)
- Tomas Ribba
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas and Departamento de Fruticultura y Enología, Facultad de Agronomía e Ingeniería Forestal. Pontificia Universidad Católica de Chile, Avenida Libertador Bernardo O'Higgins, Santiago, Chile
| | - Fernanda Garrido-Vargas
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas and Departamento de Fruticultura y Enología, Facultad de Agronomía e Ingeniería Forestal. Pontificia Universidad Católica de Chile, Avenida Libertador Bernardo O'Higgins, Santiago, Chile
| | - José Antonio O'Brien
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas and Departamento de Fruticultura y Enología, Facultad de Agronomía e Ingeniería Forestal. Pontificia Universidad Católica de Chile, Avenida Libertador Bernardo O'Higgins, Santiago, Chile
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24
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Moret B, Marhava P, Aliaga Fandino AC, Hardtke CS, Ten Tusscher KHW. Local auxin competition explains fragmented differentiation patterns. Nat Commun 2020; 11:2965. [PMID: 32528082 PMCID: PMC7289883 DOI: 10.1038/s41467-020-16803-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/20/2020] [Indexed: 01/04/2023] Open
Abstract
Trajectories of cellular ontogeny are tightly controlled and often involve feedback-regulated molecular antagonism. For example, sieve element differentiation along developing protophloem cell files of Arabidopsis roots requires two antagonistic regulators of auxin efflux. Paradoxically, loss-of-function in either regulator triggers similar, seemingly stochastic differentiation failures of individual sieve element precursors. Here we show that these patterning defects are distinct and non-random. They can be explained by auxin-dependent bistability that emerges from competition for auxin between neighboring cells. This bistability depends on the presence of an auxin influx facilitator, and can be triggered by either flux enhancement or repression. Our results uncover a hitherto overlooked aspect of auxin uptake, and highlight the contributions of local auxin influx, efflux and biosynthesis to protophloem formation. Moreover, the combined experimental-modeling approach suggests that without auxin efflux homeostasis, auxin influx interferes with coordinated differentiation. Sieve element differentiation in Arabidopsis roots requires two antagonistic regulators of auxin efflux, BRX and PAX. Here the authors show that together they coordinate sieve element formation by preventing cell fate bistability emerging from AUX1-mediated competition for auxin between neighboring cells.
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Affiliation(s)
- Bernard Moret
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland
| | - Petra Marhava
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland
| | - Ana Cecilia Aliaga Fandino
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland
| | - Christian S Hardtke
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland.
| | - Kirsten H W Ten Tusscher
- Theoretical Biology, Department of Biology, Utrecht University, 3584 CH, Utrecht, The Netherlands.
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25
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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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26
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Abstract
Crop loss due to soil salinization is an increasing threat to agriculture worldwide. This review provides an overview of cellular and physiological mechanisms in plant responses to salt. We place cellular responses in a time- and tissue-dependent context in order to link them to observed phases in growth rate that occur in response to stress. Recent advances in phenotyping can now functionally or genetically link cellular signaling responses, ion transport, water management, and gene expression to growth, development, and survival. Halophytes, which are naturally salt-tolerant plants, are highlighted as success stories to learn from. We emphasize that (a) filling the major knowledge gaps in salt-induced signaling pathways, (b) increasing the spatial and temporal resolution of our knowledge of salt stress responses, (c) discovering and considering crop-specific responses, and (d) including halophytes in our comparative studies are all essential in order to take our approaches to increasing crop yields in saline soils to the next level.
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Affiliation(s)
- Eva van Zelm
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands;
| | - Yanxia Zhang
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands;
| | - Christa Testerink
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands;
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27
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Mellor NL, Voß U, Janes G, Bennett MJ, Wells DM, Band LR. Auxin fluxes through plasmodesmata modify root-tip auxin distribution. Development 2020; 147:dev181669. [PMID: 32229613 PMCID: PMC7132777 DOI: 10.1242/dev.181669] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 02/17/2020] [Indexed: 01/05/2023]
Abstract
Auxin is a key signal regulating plant growth and development. It is well established that auxin dynamics depend on the spatial distribution of efflux and influx carriers on the cell membranes. In this study, we employ a systems approach to characterise an alternative symplastic pathway for auxin mobilisation via plasmodesmata, which function as intercellular pores linking the cytoplasm of adjacent cells. To investigate the role of plasmodesmata in auxin patterning, we developed a multicellular model of the Arabidopsis root tip. We tested the model predictions using the DII-VENUS auxin response reporter, comparing the predicted and observed DII-VENUS distributions using genetic and chemical perturbations designed to affect both carrier-mediated and plasmodesmatal auxin fluxes. The model revealed that carrier-mediated transport alone cannot explain the experimentally determined auxin distribution in the root tip. In contrast, a composite model that incorporates both carrier-mediated and plasmodesmatal auxin fluxes re-capitulates the root-tip auxin distribution. We found that auxin fluxes through plasmodesmata enable auxin reflux and increase total root-tip auxin. We conclude that auxin fluxes through plasmodesmata modify the auxin distribution created by efflux and influx carriers.
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Affiliation(s)
- Nathan L Mellor
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Ute Voß
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - George Janes
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Malcolm J Bennett
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Darren M Wells
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Leah R Band
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
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28
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Korver RA, van den Berg T, Meyer AJ, Galvan‐Ampudia CS, ten Tusscher KH, Testerink C. Halotropism requires phospholipase Dζ1-mediated modulation of cellular polarity of auxin transport carriers. PLANT, CELL & ENVIRONMENT 2020; 43:143-158. [PMID: 31430837 PMCID: PMC6972530 DOI: 10.1111/pce.13646] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/05/2019] [Accepted: 08/17/2019] [Indexed: 05/20/2023]
Abstract
Endocytosis and relocalization of auxin carriers represent important mechanisms for adaptive plant growth and developmental responses. Both root gravitropism and halotropism have been shown to be dependent on relocalization of auxin transporters. Following their homology to mammalian phospholipase Ds (PLDs), plant PLDζ-type enzymes are likely candidates to regulate auxin carrier endocytosis. We investigated root tropic responses for an Arabidopsis pldζ1-KO mutant and its effect on the dynamics of two auxin transporters during salt stress, that is, PIN2 and AUX1. We found altered root growth and halotropic and gravitropic responses in the absence of PLDζ1 and report a role for PLDζ1 in the polar localization of PIN2. Additionally, irrespective of the genetic background, salt stress induced changes in AUX1 polarity. Utilizing our previous computational model, we found that these novel salt-induced AUX1 changes contribute to halotropic auxin asymmetry. We also report the formation of "osmotic stress-induced membrane structures." These large membrane structures are formed at the plasma membrane shortly after NaCl or sorbitol treatment and have a prolonged presence in a pldζ1 mutant. Taken together, these results show a crucial role for PLDζ1 in both ionic and osmotic stress-induced auxin carrier dynamics during salt stress.
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Affiliation(s)
- Ruud A. Korver
- Plant Physiology and Cell Biology, Swammerdam Institute for Life SciencesUniversity of Amsterdam1098XHAmsterdamThe Netherlands
| | - Thea van den Berg
- Theoretical Biology, Department of BiologyUtrecht University3584CHUtrechtThe Netherlands
| | - A. Jessica Meyer
- Plant Physiology and Cell Biology, Swammerdam Institute for Life SciencesUniversity of Amsterdam1098XHAmsterdamThe Netherlands
- Laboratory of Plant PhysiologyWageningen University & Research6700AAWageningenThe Netherlands
| | - Carlos S. Galvan‐Ampudia
- Plant Physiology and Cell Biology, Swammerdam Institute for Life SciencesUniversity of Amsterdam1098XHAmsterdamThe Netherlands
| | | | - Christa Testerink
- Plant Physiology and Cell Biology, Swammerdam Institute for Life SciencesUniversity of Amsterdam1098XHAmsterdamThe Netherlands
- Laboratory of Plant PhysiologyWageningen University & Research6700AAWageningenThe Netherlands
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29
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Deolu-Ajayi AO, Meyer AJ, Haring MA, Julkowska MM, Testerink C. Genetic Loci Associated with Early Salt Stress Responses of Roots. iScience 2019; 21:458-473. [PMID: 31707259 PMCID: PMC6849332 DOI: 10.1016/j.isci.2019.10.043] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/16/2019] [Accepted: 10/22/2019] [Indexed: 12/23/2022] Open
Abstract
Salinity is a devastating abiotic stress accounting for major crop losses yearly. Plant roots can strikingly grow away from high-salt patches. This response is termed halotropism and occurs through auxin redistribution in roots in response to a salt gradient. Here, a natural variation screen for the early and NaCl-specific halotropic response of 333 Arabidopsis accessions revealed quantitative differences in the first 24 h. These data were successfully used to identify genetic components associated with the response through Genome-Wide Association Study (GWAS). Follow-up characterization of knockout mutants in Col-0 background confirmed the role of transcription factor WRKY25, cation-proton exchanger CHX13, and a gene of unknown function DOB1 (Double Bending 1) in halotropism. In chx13 and dob1 mutants, ion accumulation and shoot biomass under salt stress were also affected. Thus, our GWAS has identified genetic components contributing to main root halotropism that provide insight into the genetic architecture underlying plant salt responses.
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Affiliation(s)
- Ayodeji O Deolu-Ajayi
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University and Research, 6708PB Wageningen, the Netherlands; Plant Physiology, Swammerdam Institute of Life Sciences, University of Amsterdam, 1098XH Amsterdam, the Netherlands
| | - A Jessica Meyer
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University and Research, 6708PB Wageningen, the Netherlands
| | - Michel A Haring
- Plant Physiology, Swammerdam Institute of Life Sciences, University of Amsterdam, 1098XH Amsterdam, the Netherlands
| | - Magdalena M Julkowska
- Department of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, 23955-6900 Thuwal-Jeddah, Kingdom of Saudi Arabia
| | - Christa Testerink
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University and Research, 6708PB Wageningen, the Netherlands.
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30
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Blakeslee JJ, Spatola Rossi T, Kriechbaumer V. Auxin biosynthesis: spatial regulation and adaptation to stress. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:5041-5049. [PMID: 31198972 DOI: 10.1093/jxb/erz283] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 06/03/2019] [Indexed: 05/25/2023]
Abstract
The plant hormone auxin is essential for plant growth and development, controlling both organ development and overall plant architecture. Auxin homeostasis is regulated by coordination of biosynthesis, transport, conjugation, sequestration/storage, and catabolism to optimize concentration-dependent growth responses and adaptive responses to temperature, water stress, herbivory, and pathogens. At present, the best defined pathway of auxin biosynthesis is the TAA/YUC route, in which the tryptophan aminotransferases TAA and TAR and YUCCA flavin-dependent monooxygenases produce the auxin indole-3-acetic acid from tryptophan. This review highlights recent advances in our knowledge of TAA/YUC-dependent auxin biosynthesis focusing on membrane localization of auxin biosynthetic enzymes, differential regulation in root and shoot tissue, and auxin biosynthesis during abiotic stress.
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Affiliation(s)
- Joshua J Blakeslee
- Department of Horticulture and Crop Science, The Ohio State University, Wooster, OH, USA
| | - Tatiana Spatola Rossi
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Verena Kriechbaumer
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
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31
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Abstract
Roots provide the primary mechanism that plants use to absorb water and nutrients from their environment. These functions are dependent on developmental mechanisms that direct root growth and branching into regions of soil where these resources are relatively abundant. Water is the most limiting factor for plant growth, and its availability is determined by the weather, soil structure, and salinity. In this review, we define the developmental pathways that regulate the direction of growth and branching pattern of the root system, which together determine the expanse of soil from which a plant can access water. The ability of plants to regulate development in response to the spatial distribution of water is a focus of many recent studies and provides a model for understanding how biological systems utilize positional cues to affect signaling and morphogenesis. A better understanding of these processes will inform approaches to improve crop water use efficiency to more sustainably feed a growing population.
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Affiliation(s)
- José R. Dinneny
- Department of Biology, Stanford University, Stanford, California 94305, USA
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32
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Shimotohno A, Scheres B. Topology of regulatory networks that guide plant meristem activity: similarities and differences. CURRENT OPINION IN PLANT BIOLOGY 2019; 51:74-80. [PMID: 31102928 DOI: 10.1016/j.pbi.2019.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 04/07/2019] [Accepted: 04/12/2019] [Indexed: 06/09/2023]
Abstract
Plants adapt their morphology in response to variable environmental conditions such as nitrate availability, drought, and temperature shifts. Three crucial aspects to this developmental plasticity are the control of initiation, identity and activity of meristems. At the cellular level, the activity of meristems is controlled by balancing self-renewal in stem cells, amplifying divisions in their daughter cells, and cell differentiation. Recent studies in plants have uncovered transcription factors regulating meristem activity at cellular resolution, and regulatory networks that couple these factors with phytohormone signalling for global plant growth regulation. Here, we highlight selected recent advances in our understanding of the multidimensional transcriptional networks that regulate meristem activity and discuss emerging insights on how a selection of environmental cues impinges on these networks.
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Affiliation(s)
- Akie Shimotohno
- Department of Biological Science, The University of Tokyo, Tokyo 113-0033, Japan.
| | - Ben Scheres
- Department of Plant Sciences, Wageningen University and Research, Wageningen 6708PB, The Netherlands; Rijk Zwaan Research and Development, Fijnaart 4793 RS, The Netherlands.
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33
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Pasternak T, Groot EP, Kazantsev FV, Teale W, Omelyanchuk N, Kovrizhnykh V, Palme K, Mironova VV. Salicylic Acid Affects Root Meristem Patterning via Auxin Distribution in a Concentration-Dependent Manner. PLANT PHYSIOLOGY 2019; 180:1725-1739. [PMID: 31036755 PMCID: PMC6752920 DOI: 10.1104/pp.19.00130] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 04/17/2019] [Indexed: 05/18/2023]
Abstract
The phytohormone salicylic acid (SA) is well known for its induction of pathogenesis-related proteins and systemic acquired resistance; SA also has specific effects on plant growth and development. Here we analyzed the effect of SA on Arabidopsis (Arabidopsis thaliana) root development. We show that exogenous SA treatment at low (below 50 µM) and high (greater than 50 µM) concentrations affect root meristem development in two different PR1-independent ways. Low-concentration SA promoted adventitious roots and altered architecture of the root apical meristem, whereas high-concentration SA inhibited all growth processes in the root. All exposures to exogenous SA led to changes in auxin synthesis and transport. A wide range of SA treatment concentrations activated auxin synthesis, but the effect of SA on auxin transport was dose dependent. Mathematical modeling of auxin synthesis and transport predicted auxin accumulation or depletion in the root tip following low- or high-concentration SA treatments, respectively. SA-induced auxin accumulation led to the formation of more layers of columella initials, an additional cortical cell layer (middle cortex), and extra files of epidermis, cortex, and endodermis cells. Suppression of SHORT ROOT and activation of CYCLIN D6;1 mediated the changes in radial architecture of the root. We propose that low-concentration SA plays an important role in shaping root meristem structure and root system architecture.
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Affiliation(s)
- Taras Pasternak
- Institute for Biology II, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany
| | - Edwin P Groot
- State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'An 271018, China
| | - Fedor V Kazantsev
- Institute of Cytology and Genetics, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - William Teale
- Institute for Biology II, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany
| | - Nadya Omelyanchuk
- Institute of Cytology and Genetics, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Vasilina Kovrizhnykh
- Institute of Cytology and Genetics, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
| | - Klaus Palme
- Institute for Biology II, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany
- Center for Biosystems Analysis, Albert-Ludwigs-University Freiburg, D-79104 Freiburg, Germany
| | - Victoria V Mironova
- Institute of Cytology and Genetics, Novosibirsk 630090, Russia
- Novosibirsk State University, Novosibirsk 630090, Russia
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34
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Santos Teixeira JA, Ten Tusscher KH. The Systems Biology of Lateral Root Formation: Connecting the Dots. MOLECULAR PLANT 2019; 12:784-803. [PMID: 30953788 DOI: 10.1016/j.molp.2019.03.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 03/20/2019] [Accepted: 03/26/2019] [Indexed: 05/29/2023]
Abstract
The root system is a major determinant of a plant's access to water and nutrients. The architecture of the root system to a large extent depends on the repeated formation of new lateral roots. In this review, we discuss lateral root development from a systems biology perspective. We focus on studies combining experiments with computational modeling that have advanced our understanding of how the auxin-centered regulatory modules involved in different stages of lateral root development exert their specific functions. Moreover, we discuss how these regulatory networks may enable robust transitions from one developmental stage to the next, a subject that thus far has received limited attention. In addition, we analyze how environmental factors impinge on these modules, and the different manners in which these environmental signals are being integrated to enable coordinated developmental decision making. Finally, we provide some suggestions for extending current models of lateral root development to incorporate multiple processes and stages. Only through more comprehensive models we can fully elucidate the cooperative effects of multiple processes on later root formation, and how one stage drives the transition to the next.
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Affiliation(s)
- J A Santos Teixeira
- Computational Developmental Biology Group, Department of Biology, Utrecht University, Utrecht, the Netherlands
| | - K H Ten Tusscher
- Computational Developmental Biology Group, Department of Biology, Utrecht University, Utrecht, the Netherlands.
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35
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Rutten JP, Ten Tusscher K. In Silico Roots: Room for Growth. TRENDS IN PLANT SCIENCE 2019; 24:250-262. [PMID: 30665820 DOI: 10.1016/j.tplants.2018.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/14/2018] [Accepted: 11/19/2018] [Indexed: 06/09/2023]
Abstract
Computational models are invaluable tools for understanding the hormonal and genetic control of root development. Thus far, models have focused on the crucial roles that auxin transport and metabolism play in determining the auxin signaling gradient that controls the root meristem. Other hormones such as cytokinins, gibberellins, and ethylene have predominantly been considered as modulators of auxin dynamics, but their underlying patterning mechanisms are currently unresolved. In addition, the effects of cell- and tissue-level growth dynamics, which induce dilution and displacement of signaling molecules, have remained unexplored. Elucidating these additional mechanisms will be essential to unravel how root growth is patterned in a robust and self-organized manner. Models incorporating growth will thus be crucial in unraveling the underlying logic of root developmental decision making.
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Affiliation(s)
- Jacob Pieter Rutten
- Computational Developmental Biology Group, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Kirsten Ten Tusscher
- Computational Developmental Biology Group, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
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36
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Li H, Wang C, Wang X, Hou P, Luo B, Song P, Pan D, Li A, Chen L. Disposable stainless steel-based electrochemical microsensor for in vivo determination of indole-3-acetic acid in soybean seedlings. Biosens Bioelectron 2019; 126:193-199. [PMID: 30415154 DOI: 10.1016/j.bios.2018.10.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/15/2018] [Accepted: 10/22/2018] [Indexed: 02/06/2023]
Abstract
In vivo detecting of plants signal molecules is of great importance for the precision farming, crop management and plant phenotyping. In this work, for in vivo detecting indole-3-acetic acid (IAA), one of phytohormones, fine stainless steel (SS) wire was used as electrode material. Highly ordered nanopores, popcorn-like Au nanostructures, Pt nanoparticles and reduced graphene oxide (ERGO) nanocomposite films, and polymerized ST film (PST) were fabricated on the SS microelectrode in turn for improving the detection effect. Using the as-prepared SS microelectrode as working electrode, two untreated SS wires as reference electrode and counter electrode respectively, a disposable electrochemical microsensor for IAA were developed. The microsensor exhibited excellent selectivity and high sensitivity with low detection limit (LOD) of 43 pg mL-1. The limit of quantity (LOQ) is 143 pg mL-1. The RSD was 7% for 12 different PST/Pt-ERGO/Au/a-SS microsensors in presence of 100 µg mL-1 IAA. Using this microsensor, IAA of the stem of soybean seedlings was detected in vivo under salt stress. Our result was also confirmed by ultra-performance liquid chromatography-mass spectrum (UPLC-MS). This is the first report for the in vivo detection of IAA in plants using SS-based electrochemical microsensor. Our sensor provides an excellent sensing platform for detecting IAA in plants in vivo.
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Affiliation(s)
- Haiyang Li
- Beijing Research Center of Intelligent Equipment for Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China; The State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, Guangzhou 510060, China
| | - Cheng Wang
- Beijing Research Center of Intelligent Equipment for Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Xiaodong Wang
- Beijing Research Center of Intelligent Equipment for Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Peichen Hou
- Beijing Research Center of Intelligent Equipment for Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Bin Luo
- Beijing Research Center of Intelligent Equipment for Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Peng Song
- Beijing Research Center of Intelligent Equipment for Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Dayu Pan
- Beijing Research Center of Intelligent Equipment for Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
| | - Aixue Li
- Beijing Research Center of Intelligent Equipment for Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
| | - Liping Chen
- Beijing Research Center of Intelligent Equipment for Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
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37
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Muthert LWF, Izzo LG, van Zanten M, Aronne G. Root Tropisms: Investigations on Earth and in Space to Unravel Plant Growth Direction. FRONTIERS IN PLANT SCIENCE 2019; 10:1807. [PMID: 32153599 PMCID: PMC7047216 DOI: 10.3389/fpls.2019.01807] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 12/24/2019] [Indexed: 05/12/2023]
Abstract
Root tropisms are important responses of plants, allowing them to adapt their growth direction. Research on plant tropisms is indispensable for future space programs that envisage plant-based life support systems for long-term missions and planet colonization. Root tropisms encompass responses toward or away from different environmental stimuli, with an underexplored level of mechanistic divergence. Research into signaling events that coordinate tropistic responses is complicated by the consistent coincidence of various environmental stimuli, often interacting via shared signaling mechanisms. On Earth the major determinant of root growth direction is the gravitational vector, acting through gravitropism and overruling most other tropistic responses to environmental stimuli. Critical advancements in the understanding of root tropisms have been achieved nullifying the gravitropic dominance with experiments performed in the microgravity environment. In this review, we summarize current knowledge on root tropisms to different environmental stimuli. We highlight that the term tropism must be used with care, because it can be easily confused with a change in root growth direction due to asymmetrical damage to the root, as can occur in apparent chemotropism, electrotropism, and magnetotropism. Clearly, the use of Arabidopsis thaliana as a model for tropism research contributed much to our understanding of the underlying regulatory processes and signaling events. However, pronounced differences in tropisms exist among species, and we argue that these should be further investigated to get a more comprehensive view of the signaling pathways and sensors. Finally, we point out that the Cholodny-Went theory of asymmetric auxin distribution remains to be the central and unifying tropistic mechanism after 100 years. Nevertheless, it becomes increasingly clear that the theory is not applicable to all root tropistic responses, and we propose further research to unravel commonalities and differences in the molecular and physiological processes orchestrating root tropisms.
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Affiliation(s)
| | - Luigi Gennaro Izzo
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
- *Correspondence: Luigi Gennaro Izzo,
| | - Martijn van Zanten
- Molecular Plant Physiology, Institute of Environmental Biology, Utrecht University, Utrecht, Netherlands
| | - Giovanna Aronne
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
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38
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Korver RA, Koevoets IT, Testerink C. Out of Shape During Stress: A Key Role for Auxin. TRENDS IN PLANT SCIENCE 2018; 23:783-793. [PMID: 29914722 PMCID: PMC6121082 DOI: 10.1016/j.tplants.2018.05.011] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 05/17/2018] [Accepted: 05/23/2018] [Indexed: 05/19/2023]
Abstract
In most abiotic stress conditions, including salinity and water deficit, the developmental plasticity of the plant root is regulated by the phytohormone auxin. Changes in auxin concentration are often attributed to changes in shoot-derived long-distance auxin flow. However, recent evidence suggests important contributions by short-distance auxin transport from local storage and local auxin biosynthesis, conjugation, and oxidation during abiotic stress. We discuss here current knowledge on long-distance auxin transport in stress responses, and subsequently debate how short-distance auxin transport and indole-3-acetic acid (IAA) metabolism play a role in influencing eventual auxin accumulation and signaling patterns. Our analysis stresses the importance of considering all these components together and highlights the use of mathematical modeling for predictions of plant physiological responses.
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Affiliation(s)
- Ruud A Korver
- University of Amsterdam, Plant Cell Biology, Swammerdam Institute for Life Sciences, 1090GE Amsterdam, The Netherlands; Laboratory of Plant Physiology, 6708PB Wageningen University and Research, Wageningen, The Netherlands
| | - Iko T Koevoets
- Laboratory of Plant Physiology, 6708PB Wageningen University and Research, Wageningen, The Netherlands
| | - Christa Testerink
- Laboratory of Plant Physiology, 6708PB Wageningen University and Research, Wageningen, The Netherlands.
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39
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Mroue S, Simeunovic A, Robert HS. Auxin production as an integrator of environmental cues for developmental growth regulation. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:201-212. [PMID: 28992278 DOI: 10.1093/jxb/erx259] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Being sessile organisms, plants have evolved mechanisms allowing them to control their growth and development in response to environmental changes. This occurs by means of complex interacting signalling networks that integrate diverse environmental cues into co-ordinated and highly regulated responses. Auxin is an essential phytohormone that functions as a signalling molecule, driving both growth and developmental processes. It is involved in numerous biological processes ranging from control of cell expansion and cell division to tissue specification, embryogenesis, and organ development. All these processes require the formation of auxin gradients established and maintained through the combined processes of biosynthesis, metabolism, and inter- and intracellular directional transport. Environmental conditions can profoundly affect the plant developmental programme, and the co-ordinated shoot and root growth ought to be fine-tuned to environmental challenges such as temperature, light, and nutrient and water content. The key role of auxin as an integrator of environmental signals has become clear in recent years, and emerging evidence implicates auxin biosynthesis as an essential component of the overall mechanisms of plants tolerance to stress. In this review, we provide an account of auxin's role as an integrator of environmental signals and, in particular, we highlight the effect of these signals on the control of auxin production.
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Affiliation(s)
- Souad Mroue
- CEITEC MU-Central European Institute of Technology, Masaryk University, Mendel Centre for Genomics and Proteomics of Plants Systems, Brno, Czech Republic
| | - Andrea Simeunovic
- CEITEC MU-Central European Institute of Technology, Masaryk University, Mendel Centre for Genomics and Proteomics of Plants Systems, Brno, Czech Republic
| | - Hélène S Robert
- CEITEC MU-Central European Institute of Technology, Masaryk University, Mendel Centre for Genomics and Proteomics of Plants Systems, Brno, Czech Republic
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Yang Y, Guo Y. Elucidating the molecular mechanisms mediating plant salt-stress responses. THE NEW PHYTOLOGIST 2018; 217:523-539. [PMID: 29205383 DOI: 10.1111/nph.14920] [Citation(s) in RCA: 621] [Impact Index Per Article: 103.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 10/11/2017] [Indexed: 05/18/2023]
Abstract
Contents Summary 523 I. Introduction 523 II. Sensing salt stress 524 III. Ion homeostasis regulation 524 IV. Metabolite and cell activity responses to salt stress 527 V. Conclusions and perspectives 532 Acknowledgements 533 References 533 SUMMARY: Excess soluble salts in soil (saline soils) are harmful to most plants. Salt imposes osmotic, ionic, and secondary stresses on plants. Over the past two decades, many determinants of salt tolerance and their regulatory mechanisms have been identified and characterized using molecular genetics and genomics approaches. This review describes recent progress in deciphering the mechanisms controlling ion homeostasis, cell activity responses, and epigenetic regulation in plants under salt stress. Finally, we highlight research areas that require further research to reveal new determinants of salt tolerance in plants.
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Affiliation(s)
- Yongqing Yang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yan Guo
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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Liu J, Moore S, Chen C, Lindsey K. Crosstalk Complexities between Auxin, Cytokinin, and Ethylene in Arabidopsis Root Development: From Experiments to Systems Modeling, and Back Again. MOLECULAR PLANT 2017; 10:1480-1496. [PMID: 29162416 DOI: 10.1016/j.molp.2017.11.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 05/23/2023]
Abstract
Understanding how hormones and genes interact to coordinate plant growth in a changing environment is a major challenge in plant developmental biology. Auxin, cytokinin, and ethylene are three important hormones that regulate many aspects of plant development. This review critically evaluates the crosstalk between the three hormones in Arabidopsis root development. We integrate a variety of experimental data into a crosstalk network, which reveals multiple layers of complexity in auxin, cytokinin, and ethylene crosstalk. In particular, data integration reveals an additional, largely overlooked link between the ethylene and cytokinin pathways, which acts through a phosphorelay mechanism. This proposed link addresses outstanding questions on whether ethylene application promotes or inhibits receptor kinase activity of the ethylene receptors. Elucidating the complexity in auxin, cytokinin, and ethylene crosstalk requires a combined experimental and systems modeling approach. We evaluate important modeling efforts for establishing how crosstalk between auxin, cytokinin, and ethylene regulates patterning in root development. We discuss how a novel methodology that iteratively combines experiments with systems modeling analysis is essential for elucidating the complexity in crosstalk of auxin, cytokinin, and ethylene in root development. Finally, we discuss the future challenges from a combined experimental and modeling perspective.
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Affiliation(s)
- Junli Liu
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Simon Moore
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Chunli Chen
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Keith Lindsey
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK.
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van den Berg T, Ten Tusscher KH. Auxin Information Processing; Partners and Interactions beyond the Usual Suspects. Int J Mol Sci 2017; 18:ijms18122585. [PMID: 29194409 PMCID: PMC5751188 DOI: 10.3390/ijms18122585] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/20/2017] [Accepted: 11/24/2017] [Indexed: 12/20/2022] Open
Abstract
Auxin plays a major role in a variety of processes involved in plant developmental patterning and its adaptation to environmental conditions. Therefore, an important question is how specificity in auxin signalling is achieved, that is, how a single signalling molecule can carry so many different types of information. In recent years, many studies on auxin specificity have been published, unravelling increasingly more details on differential auxin sensitivity, expression domains and downstream partners of the auxin receptors (transport inhibitor response 1 (TIR1) and other auxin signaling F-box proteins (AFB)), transcriptional repressors that are degraded in response to auxin (AUX/IAA) and downstream auxin response factors (ARF) that together constitute the plant’s major auxin response pathways. These data are critical to explain how, in the same cells, different auxin levels may trigger different responses, as well as how in different spatial or temporal contexts similar auxin signals converge to different responses. However, these insights do not yet answer more complex questions regarding auxin specificity. As an example, they leave open the question of how similar sized auxin changes at similar locations result in different responses depending on the duration and spatial extent of the fluctuation in auxin levels. Similarly, it leaves unanswered how, in the case of certain tropisms, small differences in signal strength at both sides of a plant organ are converted into an instructive auxin asymmetry that enables a robust tropic response. Finally, it does not explain how, in certain cases, substantially different auxin levels become translated into similar cellular responses, while in other cases similar auxin levels, even when combined with similar auxin response machinery, may trigger different responses. In this review, we illustrate how considering the regulatory networks and contexts in which auxin signalling takes place helps answer these types of fundamental questions.
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Affiliation(s)
- Thea van den Berg
- Theoretical Biology, Department of Biology, Utrecht University, 3584 CH Utrecht, The Netherlands.
| | - Kirsten H Ten Tusscher
- Theoretical Biology, Department of Biology, Utrecht University, 3584 CH Utrecht, The Netherlands.
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Abstract
The luxurious vegetation at Sanya, the most southern location in China on the island of Hainan, provided a perfect environment for the 'Auxin 2016' meeting in October. As we review here, participants from all around the world discussed the latest advances in auxin transport, metabolism and signaling pathways, highlighting how auxin acts during plant development and in response to the environment in combination with other hormones. The meeting also provided a rich perspective on the evolution of the role of auxin, from algae to higher plants.
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Affiliation(s)
- Teva Vernoux
- Laboratoire Reproduction et Développement des Plantes, University of Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon F-69342, France
| | - Stéphanie Robert
- Swedish University of Agricultural Sciences, Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Umeå 90183, Sweden
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Han EH, Petrella DP, Blakeslee JJ. 'Bending' models of halotropism: incorporating protein phosphatase 2A, ABCB transporters, and auxin metabolism. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3071-3089. [PMID: 28899081 DOI: 10.1093/jxb/erx127] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Salt stress causes worldwide reductions in agricultural yields, a problem that is exacerbated by the depletion of global freshwater reserves and the use of contaminated or recycled water (i.e. effluent water). Additionally, salt stress can occur as cultivated areas are subjected to frequent rounds of irrigation followed by periods of moderate to severe evapotranspiration, which can result in the heterogeneous aggregation of salts in agricultural soils. Our understanding of the later stages of salt stress and the mechanisms by which salt is transported out of cells and roots has greatly improved over the last decade. The precise mechanisms by which plant roots perceive salt stress and translate this perception into adaptive, directional growth away from increased salt concentrations (i.e. halotropism), however, are not well understood. Here, we provide a review of the current knowledge surrounding the early responses to salt stress and the initiation of halotropism, including lipid signaling, protein phosphorylation cascades, and changes in auxin metabolism and/or transport. Current models of halotropism have focused on the role of PIN2- and PIN1-mediated auxin efflux in initiating and controlling halotropism. Recent studies, however, suggest that additional factors such as ABCB transporters, protein phosphatase 2A activity, and auxin metabolism should be included in the model of halotropic growth.
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Affiliation(s)
- Eun Hyang Han
- Department of Horticulture and Crop Science, The Ohio State University/OARDC, Wooster, OH, USA
| | - Dominic P Petrella
- Department of Horticulture and Crop Science, The Ohio State University/OARDC, Wooster, OH, USA
| | - Joshua J Blakeslee
- Department of Horticulture and Crop Science, OARDC Metabolite Analysis Cluster (OMAC), The Ohio State University/OARDC, Wooster, OH, USA
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Koevoets IT, Venema JH, Elzenga JTM, Testerink C. Roots Withstanding their Environment: Exploiting Root System Architecture Responses to Abiotic Stress to Improve Crop Tolerance. FRONTIERS IN PLANT SCIENCE 2016; 7:1335. [PMID: 27630659 PMCID: PMC5005332 DOI: 10.3389/fpls.2016.01335] [Citation(s) in RCA: 194] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/18/2016] [Indexed: 05/18/2023]
Abstract
To face future challenges in crop production dictated by global climate changes, breeders and plant researchers collaborate to develop productive crops that are able to withstand a wide range of biotic and abiotic stresses. However, crop selection is often focused on shoot performance alone, as observation of root properties is more complex and asks for artificial and extensive phenotyping platforms. In addition, most root research focuses on development, while a direct link to the functionality of plasticity in root development for tolerance is often lacking. In this paper we review the currently known root system architecture (RSA) responses in Arabidopsis and a number of crop species to a range of abiotic stresses, including nutrient limitation, drought, salinity, flooding, and extreme temperatures. For each of these stresses, the key molecular and cellular mechanisms underlying the RSA response are highlighted. To explore the relevance for crop selection, we especially review and discuss studies linking root architectural responses to stress tolerance. This will provide a first step toward understanding the relevance of adaptive root development for a plant's response to its environment. We suggest that functional evidence on the role of root plasticity will support breeders in their efforts to include root properties in their current selection pipeline for abiotic stress tolerance, aimed to improve the robustness of crops.
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Affiliation(s)
- Iko T. Koevoets
- Swammerdam Institute for Life Sciences, Plant Cell Biology, University of AmsterdamAmsterdam, Netherlands
| | - Jan Henk Venema
- Genomics Research in Ecology and Evolution in Nature – Plant Physiology, Groningen Institute for Evolutionary Life Sciences, University of GroningenGroningen, Netherlands
| | - J. Theo. M. Elzenga
- Genomics Research in Ecology and Evolution in Nature – Plant Physiology, Groningen Institute for Evolutionary Life Sciences, University of GroningenGroningen, Netherlands
| | - Christa Testerink
- Swammerdam Institute for Life Sciences, Plant Cell Biology, University of AmsterdamAmsterdam, Netherlands
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