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Muro K, Kamiyo J, Wang S, Geldner N, Takano J. Casparian strips prevent apoplastic diffusion of boric acid into root steles for excess B tolerance. FRONTIERS IN PLANT SCIENCE 2023; 14:988419. [PMID: 38162298 PMCID: PMC10755862 DOI: 10.3389/fpls.2023.988419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 12/01/2023] [Indexed: 01/03/2024]
Abstract
Casparian strips are ring-like structures consisting of lignin, sealing the apoplastic space between endodermal cells. They are thought to have important functions in controlling radial transport of nutrients and toxic elements in roots. However, Arabidopsis mutants with a defective Casparian strip structure have been found to maintain nutrient homeostasis in ranges supportive of growth under standard laboratory conditions. In this study, we investigated the function of Casparian strips under excess boron (B) conditions using sgn3 and sgn4 mutants with defective Casparian strip development but which do not exhibit excessive deposition of suberin, another endodermal diffusion barrier. The growth of sgn3 and sgn4 mutants did not differ significantly from that of wild-type (WT) plants under different B conditions in plate cultures; however, they were highly sensitive to B excess in hydroponic culture, where transpiration drives the translocation of boric acid toward the shoot. In hydroponic culture with sufficient to excess boric acid, B accumulation in shoots of the sgn3 and sgn4 mutants was higher than that in the WT. A time-course tracer study using 10B-enriched boric acid at a sufficient or slightly excessive concentration showed higher translocation of B into shoots of the sgn3 and sgn4 mutants. Furthermore, a genetically encoded biosensor for boric acid expressed under a stele-specific promoter (proCIF2:NIP5;1 5'UTR : Eluc-PEST) visualized faster boric acid flux into the mutant steles. Collectively, our results demonstrate the importance of Casparian strips in preventing apoplastic diffusion of boric acid into the stele under excess supply.
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Affiliation(s)
- Keita Muro
- Department of Agricultural Biology, Graduate School of Agriculture, Osaka Metropolitan University, Sakai, Japan
| | - Jio Kamiyo
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Japan
| | - Sheliang Wang
- Department Of Soil Science and Plant Nutrition, College of Resources and Environment, Huazhong Agricultural University, Wuhan, China
| | - Niko Geldner
- Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland
| | - Junpei Takano
- Department of Agricultural Biology, Graduate School of Agriculture, Osaka Metropolitan University, Sakai, Japan
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2
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Sadoine M, De Michele R, Župunski M, Grossmann G, Castro-Rodríguez V. Monitoring nutrients in plants with genetically encoded sensors: achievements and perspectives. PLANT PHYSIOLOGY 2023; 193:195-216. [PMID: 37307576 PMCID: PMC10469547 DOI: 10.1093/plphys/kiad337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 05/16/2023] [Accepted: 05/17/2023] [Indexed: 06/14/2023]
Abstract
Understanding mechanisms of nutrient allocation in organisms requires precise knowledge of the spatiotemporal dynamics of small molecules in vivo. Genetically encoded sensors are powerful tools for studying nutrient distribution and dynamics, as they enable minimally invasive monitoring of nutrient steady-state levels in situ. Numerous types of genetically encoded sensors for nutrients have been designed and applied in mammalian cells and fungi. However, to date, their application for visualizing changing nutrient levels in planta remains limited. Systematic sensor-based approaches could provide the quantitative, kinetic information on tissue-specific, cellular, and subcellular distributions and dynamics of nutrients in situ that is needed for the development of theoretical nutrient flux models that form the basis for future crop engineering. Here, we review various approaches that can be used to measure nutrients in planta with an overview over conventional techniques, as well as genetically encoded sensors currently available for nutrient monitoring, and discuss their strengths and limitations. We provide a list of currently available sensors and summarize approaches for their application at the level of cellular compartments and organelles. When used in combination with bioassays on intact organisms and precise, yet destructive analytical methods, the spatiotemporal resolution of sensors offers the prospect of a holistic understanding of nutrient flux in plants.
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Affiliation(s)
- Mayuri Sadoine
- Institute of Cell and Interaction Biology, Heinrich-Heine Universität Düsseldorf, Düsseldorf 40225, Germany
| | - Roberto De Michele
- Institute of Biosciences and Bioresources, National Research Council of Italy, Palermo 90129, Italy
| | - Milan Župunski
- Institute of Cell and Interaction Biology, Heinrich-Heine Universität Düsseldorf, Düsseldorf 40225, Germany
| | - Guido Grossmann
- Institute of Cell and Interaction Biology, Heinrich-Heine Universität Düsseldorf, Düsseldorf 40225, Germany
- Cluster of Excellence on Plant Sciences, Heinrich-Heine Universität Düsseldorf, Düsseldorf 40225, Germany
| | - Vanessa Castro-Rodríguez
- Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, Málaga 29071, Spain
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3
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Bolaños L, Abreu I, Bonilla I, Camacho-Cristóbal JJ, Reguera M. What Can Boron Deficiency Symptoms Tell Us about Its Function and Regulation? PLANTS (BASEL, SWITZERLAND) 2023; 12:777. [PMID: 36840125 PMCID: PMC9963425 DOI: 10.3390/plants12040777] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/11/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
On the eve of the 100th anniversary of Dr. Warington's discovery of boron (B) as a nutrient essential for higher plants, "boronists" have struggled to demonstrate a role beyond its structural function in cell walls dimerizing pectin molecules of rhamnogalacturonan II (RGII). In this regard, B deficiency has been associated with a plethora of symptoms in plants that include macroscopic symptoms like growth arrest and cell death and biochemical or molecular symptoms that include changes in cell wall pore size, apoplast acidification, or a steep ROS production that leads to an oxidative burst. Aiming to shed light on B functions in plant biology, we proposed here a unifying model integrating the current knowledge about B function(s) in plants to explain why B deficiency can cause such remarkable effects on plant growth and development, impacting crop productivity. In addition, based on recent experimental evidence that suggests the existence of different B ligands other than RGII in plant cells, namely glycolipids, and glycoproteins, we proposed an experimental pipeline to identify putative missing ligands and to determine how they would integrate into the above-mentioned model.
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Affiliation(s)
- Luis Bolaños
- Departamento de Biología, Universidad Autónoma de Madrid, c/Darwin 2, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Isidro Abreu
- Departamento de Biología, Universidad Autónoma de Madrid, c/Darwin 2, Campus de Cantoblanco, 28049 Madrid, Spain
- Department of Biology, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Ildefonso Bonilla
- Departamento de Biología, Universidad Autónoma de Madrid, c/Darwin 2, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Juan J. Camacho-Cristóbal
- Departamento de Fisiología, Anatomía y Biología Celular, Facultad de Ciencias Experimentales, Universidad Pablo de Olavide, 41013 Sevilla, Spain
| | - María Reguera
- Departamento de Biología, Universidad Autónoma de Madrid, c/Darwin 2, Campus de Cantoblanco, 28049 Madrid, Spain
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4
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Anand U, Chandel AKS, Oleksak P, Mishra A, Krejcar O, Raval IH, Dey A, Kuca K. Recent advances in the potential applications of luminescence-based, SPR-based, and carbon-based biosensors. Appl Microbiol Biotechnol 2022; 106:2827-2853. [PMID: 35384450 PMCID: PMC8984675 DOI: 10.1007/s00253-022-11901-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 03/23/2022] [Accepted: 03/26/2022] [Indexed: 12/20/2022]
Abstract
Abstract The need for biosensors has evolved in the detection of molecules, diseases, and pollution from various sources. This requirement has headed to the development of accurate and powerful equipment for analysis using biological sensing component as a biosensor. Biosensors have the advantage of rapid detection that can beat the conventional methods for the detection of the same molecules. Bio-chemiluminescence-based sensors are very sensitive during use in biological immune assay systems. Optical biosensors are emerging with time as they have the advantage that they act with a change in the refractive index. Carbon nanotube-based sensors are another area that has an important role in the biosensor field. Bioluminescence gives much higher quantum yields than classical chemiluminescence. Electro-generated bioluminescence has the advantage of miniature size and can produce a high signal-to-noise ratio and the controlled emission. Recent advances in biological techniques and instrumentation involving fluorescence tag to nanomaterials have increased the sensitivity limit of biosensors. Integrated approaches provided a better perspective for developing specific and sensitive biosensors with high regenerative potentials. This paper mainly focuses on sensors that are important for the detection of multiple molecules related to clinical and environmental applications. Key points • The review focusses on the applications of luminescence-based, surface plasmon resonance-based, carbon nanotube-based, and graphene-based biosensors • Potential clinical, environmental, agricultural, and food industry applications/uses of biosensors have been critically reviewed • The current limitations in this field are discussed, as well as the prospects for future advancement
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Affiliation(s)
- Uttpal Anand
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105, Beer Sheva, Israel
| | - Arvind K Singh Chandel
- Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Patrik Oleksak
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, 50003, Hradec Kralove, Czech Republic
| | - Amarnath Mishra
- Faculty of Science and Technology, Amity Institute of Forensic Sciences, Amity University Uttar Pradesh, Noida, 201313, India.
| | - Ondrej Krejcar
- Center for Basic and Applied Science, Faculty of Informatics and Management, University of Hradec Kralove, 50003, Hradec Kralove, Czech Republic
| | - Ishan H Raval
- Council of Scientific and Industrial Research - Central Salt and Marine Chemicals Institute, Gijubhai Badheka Marg, Bhavnagar, Gujarat, 364002, India
| | - Abhijit Dey
- Department of Life Sciences, Presidency University, 86/1 College Street, Kolkata, 700073, West Bengal, India
| | - Kamil Kuca
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, 50003, Hradec Kralove, Czech Republic.
- Center for Basic and Applied Science, Faculty of Informatics and Management, University of Hradec Kralove, 50003, Hradec Kralove, Czech Republic.
- Biomedical Research Center, University Hospital Hradec Kralove, 50005, Hradec Kralove, Czech Republic.
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Matthes MS, Darnell Z, Best NB, Guthrie K, Robil JM, Amstutz J, Durbak A, McSteen P. Defects in meristem maintenance, cell division, and cytokinin signaling are early responses in the boron deficient maize mutant tassel-less1. PHYSIOLOGIA PLANTARUM 2022; 174:e13670. [PMID: 35292977 DOI: 10.1111/ppl.13670] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 02/28/2022] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
Meristems house the stem cells needed for the developmental plasticity observed in adverse environmental conditions and are crucial for determining plant architecture. Meristem development is particularly sensitive to deficiencies of the micronutrient boron, yet how boron integrates into meristem development pathways is unknown. We addressed this question using the boron-deficient maize mutant, tassel-less1 (tls1). Reduced boron uptake in tls1 leads to a progressive impairment of meristem development that manifests in vegetative and reproductive defects. We show, that the tls1 tassel phenotype (male reproductive structure) was partially suppressed by mutations in the CLAVATA1 (CLV1)-ortholog, thick tassel dwarf1 (td1), but not by other mutants in the well characterized CLV-WUSCHEL pathway, which controls meristem size. The suppression of tls1 by td1 correlates with altered signaling of the phytohormone cytokinin. In contrast, mutations in the meristem maintenance gene knotted1 (kn1) enhanced both vegetative and reproductive defects in tls1. In addition, reduced transcript levels of kn1 and cell cycle genes are early defects in tls1 tassel meristems. Our results show that specific meristem maintenance and hormone pathways are affected in tls1, and suggest that reduced boron levels induced by tls1 are the underlying cause of the observed defects. We, therefore, provide new insights into the molecular mechanisms affected by boron deficiency in maize, leading to a better understanding of how genetic and environmental factors integrate during shoot meristem development.
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Affiliation(s)
- Michaela S Matthes
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, USA
| | - Zoe Darnell
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, USA
| | - Norman B Best
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, USA
| | - Katy Guthrie
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, USA
| | - Janlo M Robil
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, USA
| | - Jen Amstutz
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, USA
| | - Amanda Durbak
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, USA
| | - Paula McSteen
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, USA
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6
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Onuh AF, Miwa K. Regulation, Diversity and Evolution of Boron Transporters in Plants. PLANT & CELL PHYSIOLOGY 2021; 62:590-599. [PMID: 33570563 DOI: 10.1093/pcp/pcab025] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
Boron (B) is an essential trace element in plants, and borate cross-linking of pectic polysaccharide rhamnogalacturonan-II (RG-II) in cell walls is required for normal cell growth. High concentrations of B are toxic to cells. Therefore, plants need to control B transport to respond to B conditions in the environment. Over the past two decades, genetic analyses of Arabidopsis thaliana have revealed that B transport is governed by two types of membrane transport molecules: NIPs (nodulin-26-like intrinsic proteins), which facilitate boric acid permeation, and BORs, which export borate from cells. In this article, we review recent findings on the (i) regulation at the cell level, (ii) diversity among plant species and (iii) evolution of these B transporters in plants. We first describe the systems regulating these B transporters at the cell level, focusing on the molecular mechanisms underlying the polar localization of proteins and B-dependent expression, as well as their physiological significance in A. thaliana. Then, we examine the presence of homologous genes and characterize the functions of NIPs and BORs in B homeostasis, in a wide range of plant species, including Brassica napus, Oryza sativa and Zea mays. Finally, we discuss the evolutionary aspects of NIPs and BORs as B transporters, and the possible relationship between the diversification of B transport and the occurrence of RG-II in plants. This review considers the sophisticated systems of B transport that are conserved among various plant species, which were established to meet mineral nutrient requirements.
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Affiliation(s)
- Amarachukwu Faith Onuh
- Division of Biosphere Science, Graduate School of Environmental Science, Hokkaido University, North-10, West-5, Kita-ku, Sapporo, 060-0810 Japan
| | - Kyoko Miwa
- Division of Biosphere Science, Graduate School of Environmental Science, Hokkaido University, North-10, West-5, Kita-ku, Sapporo, 060-0810 Japan
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7
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Pereira GL, Siqueira JA, Batista-Silva W, Cardoso FB, Nunes-Nesi A, Araújo WL. Boron: More Than an Essential Element for Land Plants? FRONTIERS IN PLANT SCIENCE 2021; 11:610307. [PMID: 33519866 PMCID: PMC7840898 DOI: 10.3389/fpls.2020.610307] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/18/2020] [Indexed: 05/17/2023]
Abstract
Although boron (B) is an element that has long been assumed to be an essential plant micronutrient, this assumption has been recently questioned. Cumulative evidence has demonstrated that the players associated with B uptake and translocation by plant roots include a sophisticated set of proteins used to cope with B levels in the soil solution. Here, we summarize compelling evidence supporting the essential role of B in mediating plant developmental programs. Overall, most plant species studied to date have exhibited specific B transporters with tight genetic coordination in response to B levels in the soil. These transporters can uptake B from the soil, which is a highly uncommon occurrence for toxic elements. Moreover, the current tools available to determine B levels cannot precisely determine B translocation dynamics. We posit that B plays a key role in plant metabolic activities. Its importance in the regulation of development of the root and shoot meristem is associated with plant developmental phase transitions, which are crucial processes in the completion of their life cycle. We provide further evidence that plants need to acquire sufficient amounts of B while protecting themselves from its toxic effects. Thus, the development of in vitro and in vivo approaches is required to accurately determine B levels, and subsequently, to define unambiguously the function of B in terrestrial plants.
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Affiliation(s)
| | | | | | | | | | - Wagner L. Araújo
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Brazil
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8
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Yoshinari A, Moe-Lange J, Kleist TJ, Cartwright HN, Quint DA, Ehrhardt DW, Frommer WB, Nakamura M. Using Genetically Encoded Fluorescent Biosensors for Quantitative In Vivo Imaging. Methods Mol Biol 2020; 2200:303-322. [PMID: 33175384 DOI: 10.1007/978-1-0716-0880-7_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023]
Abstract
Fluorescent biosensors are powerful tools for tracking analytes or cellular processes in live organisms and allowing visualization of the spatial and temporal dynamics of cellular regulators. Fluorescent protein (FP)-based biosensors are extensively employed due to their high selectivity and low invasiveness. A variety of FP-based biosensors have been engineered and applied in plant research to visualize dynamic changes in pH, redox state, concentration of molecules (ions, sugars, peptides, ATP, reactive oxygen species, and phytohormones), and activity of transporters. In this chapter, we briefly summarize reported uses of FP-based biosensors in planta and show simple methods to monitor the dynamics of intracellular Ca2+ in Arabidopsis thaliana using a ratiometric genetically encoded Ca2+ indicator, MatryoshCaMP6s.
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Affiliation(s)
- Akira Yoshinari
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
| | - Jacob Moe-Lange
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Thomas J Kleist
- Institute for Molecular Physiology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Heather N Cartwright
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA
| | - David A Quint
- Center for Cellular and Biomolecular Machines (NSF-Crest), University of California, Merced, CA, USA
| | - David W Ehrhardt
- Department of Biology, Stanford University, Stanford, CA, USA
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA
| | - Wolf B Frommer
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
- Institute for Molecular Physiology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Masayoshi Nakamura
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan.
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9
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Matthes MS, Robil JM, McSteen P. From element to development: the power of the essential micronutrient boron to shape morphological processes in plants. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:1681-1693. [PMID: 31985801 PMCID: PMC7067301 DOI: 10.1093/jxb/eraa042] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 01/25/2020] [Indexed: 05/27/2023]
Abstract
Deficiency of the essential nutrient boron (B) in the soil is one of the most widespread micronutrient deficiencies worldwide, leading to developmental defects in root and shoot tissues of plants, and severe yield reductions in many crops. Despite this agricultural importance, the underlying mechanisms of how B shapes plant developmental and morphological processes are still not unequivocally understood in detail. This review evaluates experimental approaches that address our current understanding of how B influences plant morphological processes by focusing on developmental defects observed under B deficiency. We assess what is known about mechanisms that control B homeostasis and specifically highlight: (i) limitations in the methodology that is used to induce B deficiency; (ii) differences between mutant phenotypes and normal plants grown under B deficiency; and (iii) recent research on analyzing interactions between B and phytohormones. Our analysis highlights the need for standardized methodology to evaluate the roles of B in the cell wall versus other parts of the cell.
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Affiliation(s)
- Michaela S Matthes
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, LSC, Columbia, MO, USA
| | - Janlo M Robil
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, LSC, Columbia, MO, USA
| | - Paula McSteen
- Division of Biological Sciences, Bond Life Sciences Center, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, LSC, Columbia, MO, USA
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10
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Assessment of a 18F-Phenylboronic Acid Radiotracer for Imaging Boron in Maize. Int J Mol Sci 2020; 21:ijms21030976. [PMID: 32024118 PMCID: PMC7037850 DOI: 10.3390/ijms21030976] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 01/29/2020] [Indexed: 11/29/2022] Open
Abstract
Boron (B) is an essential plant micronutrient. Deficiencies of B have drastic consequences on plant development leading to crop yield losses and reductions in root and shoot growth. Understanding the molecular and cellular consequences of B deficiency is challenging, partly because of the limited availability of B imaging techniques. In this report we demonstrate the efficacy of using 4-fluorophenylboronic acid (FPBA) as a B imaging agent, which is a derivative of the B deficiency mimic phenylboronic acid (PBA). We show that radioactively labelled [18F]FPBA (t½=110 m) accumulates at the root tip, the root elongation zone and at lateral root initiation sites in maize roots, and also translocates to the shoot where it accumulates along the leaf edges. Treatment of maize seedlings using FPBA and PBA causes a shortened primary root phenotype with absence of lateral roots in a dose-dependent manner. The primary root defects can be partially rescued by the addition of boric acid indicating that PBA can be used to induce B deficiency in maize and that radioactively labelled FPBA can be used to image sites of B demand on a tissue level.
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