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Zexer N, Diehn S, Elbaum R. Deposition of silica in sorghum root endodermis modifies the chemistry of associated lignin. Front Plant Sci 2024; 15:1370479. [PMID: 38633454 PMCID: PMC11021652 DOI: 10.3389/fpls.2024.1370479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 03/05/2024] [Indexed: 04/19/2024]
Abstract
Silica aggregates at the endodermis of sorghum roots. Aggregation follows a spotted pattern of locally deposited lignin at the inner tangential cell walls. Autofluorescence microscopy suggests that non-silicified (-Si) lignin spots are composed of two distinct concentric regions of varied composition. To highlight variations in lignin chemistry, we used Raman microspectroscopy to map the endodermal cell wall and silica aggregation sites in sorghum roots grown hydroponically with or without Si amendment. In +Si samples, the aggregate center was characterized by typical lignin monomer bands surrounded by lignin with a low level of polymerization. Farther from the spot, polysaccharide concentration increased and soluble silicic acid was detected in addition to silica bands. In -Si samples, the main band at the spot center was assigned to lignin radicals and highly polymerized lignin. Both +Si and -Si loci were enriched by aromatic carbonyls. We propose that at silica aggregation sites, carbonyl rich lignin monomers are locally exported to the apoplast. These monomers are radicalized and polymerized into short lignin polymers. In the presence of silicic acid, bonds typically involved in lignin extension, bind to silanols and nucleate silica aggregates near the monomer extrusion loci. This process inhibits further polymerization of lignin. In -Si samples, the monomers diffuse farther in the wall and crosslink with cell wall polymers, forming a ring of dense lignified cell wall around their export sites.
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Affiliation(s)
- Nerya Zexer
- Department of Biology, The Pennsylvania State University, University Park, PA, United States
| | - Sabrina Diehn
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
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2
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Diehn S, Kirby N, Ben-Zeev S, Alemu MD, Saranga Y, Elbaum R. Raman developmental markers in root cell walls are associated with lodging tendency in tef. Planta 2024; 259:54. [PMID: 38294548 PMCID: PMC10830713 DOI: 10.1007/s00425-023-04298-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 11/17/2023] [Indexed: 02/01/2024]
Abstract
MAIN CONCLUSION Using Raman micro-spectroscopy on tef roots, we could monitor cell wall maturation in lines with varied genetic lodging tendency. We describe the developing cell wall composition in root endodermis and cylinder tissue. Tef [Eragrostis tef (Zucc.) Trotter] is an important staple crop in Ethiopia and Eritrea, producing gluten-free and protein-rich grains. However, this crop is not adapted to modern farming practices due to high lodging susceptibility, which prevents the application of mechanical harvest. Lodging describes the displacement of roots (root lodging) or fracture of culms (stem lodging), forcing plants to bend or fall from their vertical position, causing significant yield losses. In this study, we aimed to understand the microstructural properties of crown roots, underlining tef tolerance/susceptibility to lodging. We analyzed plants at 5 and 10 weeks after emergence and compared trellised to lodged plants. Root cross sections from different tef genotypes were characterized by scanning electron microscopy, micro-computed tomography, and Raman micro-spectroscopy. Lodging susceptible genotypes exhibited early tissue maturation, including developed aerenchyma, intensive lignification, and lignin with high levels of crosslinks. A comparison between trellised and lodged plants suggested that lodging itself does not affect the histology of root tissue. Furthermore, cell wall composition along plant maturation was typical to each of the tested genotypes independently of trellising. Our results suggest that it is possible to select lines that exhibit slow maturation of crown roots. Such lines are predicted to show reduction in lodging and facilitate mechanical harvest.
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Affiliation(s)
- Sabrina Diehn
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001, Rehovot, Israel.
| | - Noa Kirby
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001, Rehovot, Israel
| | - Shiran Ben-Zeev
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001, Rehovot, Israel
| | - Muluken Demelie Alemu
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001, Rehovot, Israel
- Ethiopian Institute of Agricultural Research, Addis Ababa, Ethiopia
| | - Yehoshua Saranga
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001, Rehovot, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001, Rehovot, Israel.
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3
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Ayieko VO, Cohen L, Diehn S, Goobes G, Elbaum R. Siliplant1 B-domain precipitates silica spheres, aggregates, or gel, depending on Si-precursor to peptide ratios. Colloids Surf B Biointerfaces 2023; 232:113582. [PMID: 37862949 DOI: 10.1016/j.colsurfb.2023.113582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 10/22/2023]
Abstract
Silica is extensively deposited by plants, however, only little is known about the molecular control over this process. Siliplant1 is the only known plant protein to precipitate biosilica. The protein contains seven repeats made of three domains. One of the domains exhibits a conserved sequence, which catalyzes silica precipitation in vitro. Here, silica was synthesized by the activity of a peptide carrying this conserved sequence. Infrared spectroscopy and thermal gravimetric analyses showed that the peptide was bound to the mineral. Scanning electron microscopy showed that silica-peptide particles of 22 ± 4 nm aggregated to spherical structures of 200-300 nm when the ratio of silicic acid to the peptide was below 183:1 molecules. When the ratio was about 183:1, similar particles aggregated into irregular structures, and silica gel formed at higher ratios. Solid-state NMR spectra indicated that the irregular aggregates were richer in Si-O-Si bonds as well as disordered peptide. Our results suggest that the peptide catalyzed the condensation of silicic acid and the formation of ∼20 nm particles, which aggregated into spheres. Excess of the peptide stabilized surface Si-OH groups that prevented spontaneous Si-O-Si bonding between aggregates. Under Si concentrations relevant to plant sap, the peptide and possibly Siliplant1, could catalyze nucleation of silica particles that aggregate into spherical aggregates.
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Affiliation(s)
- Vincent Otieno Ayieko
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel
| | - Lilian Cohen
- Department of Chemistry, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Sabrina Diehn
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel
| | - Gil Goobes
- Department of Chemistry, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel.
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Biru FN, Cazzonelli CI, Elbaum R, Johnson SN. Silicon-mediated herbivore defence in a pasture grass under reduced and Anthropocene levels of CO 2. Front Plant Sci 2023; 14:1268043. [PMID: 38023935 PMCID: PMC10646432 DOI: 10.3389/fpls.2023.1268043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023]
Abstract
The uptake and accumulation of silicon (Si) in grass plants play a crucial role in alleviating both biotic and abiotic stresses. Si supplementation has been reported to increase activity of defence-related antioxidant enzyme, which helps to reduce oxidative stress caused by reactive oxygen species (ROS) following herbivore attack. Atmospheric CO2 levels are known to affect Si accumulation in grasses; reduced CO2 concentrations increase Si accumulation whereas elevated CO2 concentrations often decrease Si accumulation. This can potentially affect antioxidant enzyme activity and subsequently insect herbivory, but this remains untested. We examined the effects of Si supplementation and herbivory by Helicoverpa armigera on antioxidant enzyme (catalase, CAT; superoxide dismutase, SOD; and ascorbate peroxidase, APX) activity in tall fescue grass (Festuca arundinacea) grown under CO2 concentrations of 200, 410, and 640 ppm representing reduced, ambient, and elevated CO2 levels, respectively. We also quantified foliar Si, carbon (C), and nitrogen (N) concentrations and determined how changes in enzymes and elemental chemistry affected H. armigera relative growth rates and plant consumption. Rising CO2 concentrations increased plant mass and foliar C but decreased foliar N and Si. Si supplementation enhanced APX and SOD activity under the ranging CO2 regimes. Si accumulation and antioxidant enzyme activity were at their highest level under reduced CO2 conditions and their lowest level under future levels of CO2. The latter corresponded with increased herbivore growth rates and plant consumption, suggesting that some grasses could become more susceptible to herbivory under projected CO2 conditions.
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Affiliation(s)
- Fikadu N. Biru
- College of Agriculture and Veterinary Medicine, Jimma University, Jimma, Ethiopia
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | | | - Rivka Elbaum
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Scott N. Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
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Zexer N, Kumar S, Elbaum R. Silica deposition in plants: scaffolding the mineralization. Ann Bot 2023; 131:897-908. [PMID: 37094329 PMCID: PMC10332400 DOI: 10.1093/aob/mcad056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/20/2023] [Indexed: 05/03/2023]
Abstract
BACKGROUND Silicon and aluminium oxides make the bulk of agricultural soils. Plants absorb dissolved silicon as silicic acid into their bodies through their roots. The silicic acid moves with transpiration to target tissues in the plant body, where it polymerizes into biogenic silica. Mostly, the mineral forms on a matrix of cell wall polymers to create a composite material. Historically, silica deposition (silicification) was supposed to occur once water evaporated from the plant surface, leaving behind an increased concentration of silicic acid within plant tissues. However, recent publications indicate that certain cell wall polymers and proteins initiate and control the extent of plant silicification. SCOPE Here we review recent publications on the polymers that scaffold the formation of biogenic plant silica, and propose a paradigm shift from spontaneous polymerization of silicic acid to dedicated active metabolic processes that control both the location and the extent of the mineralization. CONCLUSION Protein activity concentrates silicic acid beyond its saturation level. Polymeric structures at the cell wall stabilize the supersaturated silicic acid and allow its flow with the transpiration stream, or bind it and allow its initial condensation. Silica nucleation and further polymerization are enabled on a polymeric scaffold, which is embedded within the mineral. Deposition is terminated once free silicic acid is consumed or the chemical moieties for its binding are saturated.
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Affiliation(s)
- Nerya Zexer
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Santosh Kumar
- Department of Biological Sciences, Birla Institute of Technology and Science-Pilani, K. K. Birla Goa Campus, Zuarinagar 403726, Goa, India
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar 751024, Odisha, India
| | - Rivka Elbaum
- R. H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 7610001, Israel
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6
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Abstract
Hydrated silica (SiO2·nH2O) aggregates in the root endodermis of grasses. Application of soluble silicates (Si) to roots is associated with variations in the balance of reactive oxygen species (ROS), increased tolerance to a broad range of stresses affecting ROS concentrations, and early lignin deposition. In sorghum (Sorghum bicolor L.), silica aggregation is patterned in an active silicification zone (ASZ) by a special type of aromatic material forming a spotted pattern. The deposition has a signature typical of lignin. Since lignin polymerization is mediated by ROS, we studied the formation of root lignin and silica controlled by ROS via modulating hydrogen peroxide (H2O2) concentrations in the growth medium. Sorghum seedlings were grown hydroponically and supplemented with Si, H2O2, and KI, an ionic compound that catalyses H2O2 decomposition. Lignin and silica deposits in the endodermis were studied by histology, scanning electron and Raman microscopies. Cell wall composition was quantified by thermal gravimetric analysis. Endodermal H2O2 concentration correlated to the extent of lignin-like deposition along the root, but did not affect its patterning in spots. Our results show that the ASZ spots were necessary for root silica aggregation, and suggest that silicification is intensified under oxidative stress as a result of increased ASZ lignin-like deposition.
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Affiliation(s)
- Nerya Zexer
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel
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7
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Shivaraj SM, Mandlik R, Bhat JA, Raturi G, Elbaum R, Alexander L, Tripathi DK, Deshmukh R, Sonah H. Outstanding Questions on the Beneficial Role of Silicon in Crop Plants. Plant Cell Physiol 2022; 63:4-18. [PMID: 34558628 DOI: 10.1093/pcp/pcab145] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 06/13/2023]
Abstract
Silicon (Si) is widely accepted as a beneficial element for plants. Despite the substantial progress made in understanding Si transport mechanisms and modes of action in plants, several questions remain unanswered. In this review, we discuss such outstanding questions and issues commonly encountered by biologists studying the role of Si in plants in relation to Si bioavailability. In recent years, advances in our understanding of the role of Si-solubilizing bacteria and the efficacy of Si nanoparticles have been made. However, there are many unknown aspects associated with structural and functional features of Si transporters, Si loading into the xylem, and the role of specialized cells like silica cells and compounds preventing Si polymerization in plant tissues. In addition, despite several 1,000 reports showing the positive effects of Si in high as well as low Si-accumulating plant species, the exact roles of Si at the molecular level are yet to be understood. Some evidence suggests that Si regulates hormonal pathways and nutrient uptake, thereby explaining various observed benefits of Si uptake. However, how Si modulates hormonal pathways or improves nutrient uptake remains to be explained. Finally, we summarize the knowledge gaps that will provide a roadmap for further research on plant silicon biology, leading to an exploration of the benefits of Si uptake to enhance crop production.
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Affiliation(s)
- S M Shivaraj
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
| | - Rushil Mandlik
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
- Department of Biotechnology, Panjab University, Chandigarh, Punjab 160014, India
| | - Javaid Akhter Bhat
- National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing 210095, China
| | - Gaurav Raturi
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
- Department of Biotechnology, Panjab University, Chandigarh, Punjab 160014, India
| | - Rivka Elbaum
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Lux Alexander
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Bratislava SK-84215, Slovakia
| | - Durgesh Kumar Tripathi
- Amity Institute of Organic Agriculture, Amity University, Noida, Uttar Pradesh 201313, India
| | - Rupesh Deshmukh
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
| | - Humira Sonah
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
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Lindtner T, Uzan AY, Eder M, Bar-On B, Elbaum R. Repetitive hygroscopic snapping movements in awns of wild oats. Acta Biomater 2021; 135:483-492. [PMID: 34506974 DOI: 10.1016/j.actbio.2021.08.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/05/2021] [Accepted: 08/27/2021] [Indexed: 11/17/2022]
Abstract
Wild oat (Avena sterilis) is a very common annual plant species. Successful seed dispersion support its wide distribution in Africa, Asia and Europe. The seed dispersal units are made of two elongated stiff awns that are attached to a pointy compartment containing two seeds. The awns bend and twist with changes in humidity, pushing the seeds along and into the soil. The present work reveals the material structure of the awns, and models their functionality as two-link robotic arms. Based on nano-to-micro structure analyses the bending and twisting hygroscopic movements are explained. The coordinated movements of two sister awns attached to one dispersal unit were followed. Our work shows that sister awns intersect typically twice every wetting-drying cycle. Once the awns cross each other, epidermal silica hairs are suggested to lock subsequent movements, resulting in stress accumulation. Sudden release of the interlocked awns induces jumps of the dispersal unit and changes in its movement direction. Our findings propose a new role to epidermis silica hairs and a new facet of wild oat seed dispersion. Reversible jumping mechanism in multiple-awn seed dispersal units may serve as a blueprint for reversibly jumping robotic systems. STATEMENT OF SIGNIFICANCE: The seed dispersal unit of wild oats carries two elongated stiff awns covered by unidirectional silica hairs. The awns bend and twist with changes in humidity, pushing the seed capsule along and into the ground. We studied structures constructing the movement mechanism and modeled the awn as a two-link robotic arm. We show that sister awns, attached to the same seed capsule, intersect twice every drying cycle. Once the awns cross each other, the epidermal silica hairs are suggested to lock any subsequent movements, causing stress accumulation. Sudden release of the interlocked awns may cause the dispersal unit to jump and change its direction. Our findings suggest a new role to silica hairs and a new dispersal mechanism in multiple-awn seed dispersal units.
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Affiliation(s)
- Tom Lindtner
- School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, Albert-Einstein-Straße 5-9, 12489, Berlin-Adlershof, Germany; Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor-Str. 2, 12489, Berlin-Adlershof, Germany; The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel
| | - Avihai Yosef Uzan
- Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Michaela Eder
- Max-Planck-Institute of Colloids and Interfaces, Department of Biomaterials, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Benny Bar-On
- Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel.
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Kumar S, Adiram-Filiba N, Blum S, Sanchez-Lopez JA, Tzfadia O, Omid A, Volpin H, Heifetz Y, Goobes G, Elbaum R. Corrigendum to: Siliplant1 protein precipitates silica in sorghum silica cells. J Exp Bot 2021; 72:6672. [PMID: 34331762 DOI: 10.1093/jxb/erab333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Affiliation(s)
- Santosh Kumar
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | | | - Shula Blum
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Javier Arturo Sanchez-Lopez
- Department of Entomology, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Oren Tzfadia
- Bioinformatics and Systems Biology, VIB/Ghent University, Gent, Belgium
| | - Ayelet Omid
- Danziger Innovations Limited, Mishmar Hashiva, Israel
| | - Hanne Volpin
- Danziger Innovations Limited, Mishmar Hashiva, Israel
| | - Yael Heifetz
- Department of Entomology, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Gil Goobes
- Department of Chemistry, Bar-Ilan University, Ramat Gan, Israel
| | - Rivka Elbaum
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
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Abstract
This article comments on: Antreich SJ, Xiao N, Huss JC, Gierlinger N. 2021. A belt for the cell: cellulosic wall thickenings and their role in morphogenesis of the 3D puzzle cells in walnut shells. Journal of Experimental Botany 72,4744–4756.
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Affiliation(s)
- Rivka Elbaum
- The Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
- Correspondence:
| | - Michael Elbaum
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
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11
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Biru FN, Islam T, Cibils-Stewart X, Cazzonelli CI, Elbaum R, Johnson SN. Anti-herbivore silicon defences in a model grass are greatest under Miocene levels of atmospheric CO 2. Glob Chang Biol 2021; 27:2959-2969. [PMID: 33772982 DOI: 10.1111/gcb.15619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 03/12/2021] [Indexed: 06/12/2023]
Abstract
Silicon (Si) has an important role in mitigating diverse biotic and abiotic stresses in plants, mainly via the silicification of plant tissues. Environmental changes such as atmospheric CO2 concentrations may affect grass Si concentrations which, in turn, can alter herbivore performance. We recently demonstrated that pre-industrial atmospheric CO2 increased Si accumulation in Brachypodium distachyon grass, yet the patterns of Si deposition in leaves and whether this affects insect herbivore performance remains unknown. Moreover, it is unclear whether CO2 -driven changes in Si accumulation are linked to changes in gas exchange (e.g. transpiration rates). We therefore investigated how pre-industrial (reduced; rCO2 , 200 ppm), ambient (aCO2 , 410 ppm) and elevated (eCO2 , 640 ppm) CO2 concentrations, in combination with Si-treatment (Si+ or Si-), affected Si accumulation in B. distachyon and its subsequent effect on the performance of the global insect pest, Helicoverpa armigera. rCO2 increased Si concentrations by 29% and 36% compared to aCO2 and eCO2 respectively. These changes were not related to observed changes in gas exchange under different CO2 regimes, however. The increased Si accumulation under rCO2 decreased herbivore relative growth rate (RGR) by 120% relative to eCO2, whereas rCO2 caused herbivore RGR to decrease by 26% compared to eCO2 . Si supplementation also increased the density of macrohairs, silica and prickle cells, which was associated with reduced herbivore performance. There was a negative correlation among macrohair density, silica cell density, prickle cell density and herbivore RGR under rCO2 suggesting that these changes in leaf surface morphology were linked to reduced performance under this CO2 regime. To our knowledge, this is the first study to demonstrate that increased Si accumulation under pre-industrial CO2 reduces insect herbivore performance. Contrastingly, we found reduced Si accumulation under higher CO2 , which suggests that some grasses may become more susceptible to insect herbivores under projected climate change scenarios.
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Affiliation(s)
- Fikadu N Biru
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- College of Agriculture and Veterinary Medicine, Jimma University, Jimma, Ethiopia
| | - Tarikul Islam
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- Department of Entomology, Faculty of Agriculture, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Ximena Cibils-Stewart
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- Instituto Nacional de Investigación Agropecuaria (INIA), Colonia, Uruguay
| | | | - Rivka Elbaum
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
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12
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Zexer N, Elbaum R. Unique lignin modifications pattern the nucleation of silica in sorghum endodermis. J Exp Bot 2020; 71:6818-6829. [PMID: 32154874 PMCID: PMC7709913 DOI: 10.1093/jxb/eraa127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 03/06/2020] [Indexed: 05/04/2023]
Abstract
Silicon dioxide in the form of hydrated silica is a component of plant tissues that can constitute several percent by dry weight in certain taxa. Nonetheless, the mechanism of plant silica formation is mostly unknown. Silicon (Si) is taken up from the soil by roots in the form of monosilicic acid molecules. The silicic acid is carried in the xylem and subsequently polymerizes in target sites to silica. In roots of sorghum (Sorghum bicolor), silica aggregates form in an orderly pattern along the inner tangential cell walls of endodermis cells. Using Raman microspectroscopy, autofluorescence, and scanning electron microscopy, we investigated the structure and composition of developing aggregates in roots of sorghum seedlings. Putative silica aggregation loci were identified in roots grown under Si starvation. These micrometer-scale spots were constructed of tightly packed modified lignin, and nucleated trace concentrations of silicic acid. Substantial variation in cell wall autofluorescence between Si+ and Si- roots demonstrated the impact of Si on cell wall chemistry. We propose that in Si- roots, the modified lignin cross-linked into the cell wall and lost its ability to nucleate silica. In Si+ roots, silica polymerized on the modified lignin and altered its structure. Our work demonstrates a high degree of control over lignin and silica deposition in cell walls.
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Affiliation(s)
- Nerya Zexer
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
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13
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Kumar S, Adiram-Filiba N, Blum S, Sanchez-Lopez JA, Tzfadia O, Omid A, Volpin H, Heifetz Y, Goobes G, Elbaum R. Siliplant1 protein precipitates silica in sorghum silica cells. J Exp Bot 2020; 71:6830-6843. [PMID: 32485738 DOI: 10.1093/jxb/eraa258] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 05/26/2020] [Indexed: 05/26/2023]
Abstract
Silicon is absorbed by plant roots as silicic acid. The acid moves with the transpiration stream to the shoot, and mineralizes as silica. In grasses, leaf epidermal cells called silica cells deposit silica in most of their volume using an unknown biological factor. Using bioinformatics tools, we identified a previously uncharacterized protein in Sorghum bicolor, which we named Siliplant1 (Slp1). Slp1 is a basic protein with seven repeat units rich in proline, lysine, and glutamic acid. We found Slp1 RNA in sorghum immature leaf and immature inflorescence. In leaves, transcription was highest just before the active silicification zone (ASZ). There, Slp1 was localized specifically to developing silica cells, packed inside vesicles and scattered throughout the cytoplasm or near the cell boundary. These vesicles fused with the membrane, releasing their content in the apoplastic space. A short peptide that is repeated five times in Slp1 precipitated silica in vitro at a biologically relevant silicic acid concentration. Transient overexpression of Slp1 in sorghum resulted in ectopic silica deposition in all leaf epidermal cell types. Our results show that Slp1 precipitates silica in sorghum silica cells.
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Affiliation(s)
- Santosh Kumar
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | | | - Shula Blum
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Javier Arturo Sanchez-Lopez
- Department of Entomology, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Oren Tzfadia
- Bioinformatics and Systems Biology, VIB/Ghent University, Gent, Belgium
| | - Ayelet Omid
- Danziger Innovations Limited, Mishmar Hashiva, Israel
| | - Hanne Volpin
- Danziger Innovations Limited, Mishmar Hashiva, Israel
| | - Yael Heifetz
- Department of Entomology, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Gil Goobes
- Department of Chemistry, Bar-Ilan University, Ramat Gan, Israel
| | - Rivka Elbaum
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
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14
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Soukup M, Rodriguez Zancajo VM, Kneipp J, Elbaum R. Formation of root silica aggregates in sorghum is an active process of the endodermis. J Exp Bot 2020; 71:6807-6817. [PMID: 31504726 PMCID: PMC7709912 DOI: 10.1093/jxb/erz387] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 08/15/2019] [Indexed: 05/10/2023]
Abstract
Silica deposition in plants is a common phenomenon that correlates with plant tolerance to various stresses. Deposition occurs mostly in cell walls, but its mechanism is unclear. Here we show that metabolic processes control the formation of silica aggregates in roots of sorghum (Sorghum bicolor L.), a model plant for silicification. Silica formation was followed in intact roots and root segments of seedlings. Root segments were treated to enhance or suppress cell wall biosynthesis. The composition of endodermal cell walls was analysed by Raman microspectroscopy, scanning electron microscopy and energy-dispersive X-ray analysis. Our results were compared with in vitro reactions simulating lignin and silica polymerization. Silica aggregates formed only in live endodermal cells that were metabolically active. Silicic acid was deposited in vitro as silica onto freshly polymerized coniferyl alcohol, simulating G-lignin, but not onto coniferyl alcohol or ferulic acid monomers. Our results show that root silica aggregates form under tight regulation by endodermal cells, independently of the transpiration stream. We raise the hypothesis that the location and extent of silicification are primed by the chemistry and structure of polymerizing lignin as it cross-links to the wall.
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Affiliation(s)
- Milan Soukup
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovicova 6, Bratislava, Slovakia
- Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava, Slovakia
| | - Victor M Rodriguez Zancajo
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
- Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava, Slovakia
| | - Janina Kneipp
- Chemistry Department and School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, Berlin, Germany
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
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15
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Biru FN, Cazzonelli CI, Elbaum R, Johnson SN. Contrasting effects of Miocene and Anthropocene levels of atmospheric CO 2 on silicon accumulation in a model grass. Biol Lett 2020; 16:20200608. [PMID: 33232651 DOI: 10.1098/rsbl.2020.0608] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Grasses are hyper-accumulators of silicon (Si), which they acquire from the soil and deposit in tissues to resist environmental stresses. Given the high metabolic costs of herbivore defensive chemicals and structural constituents (e.g. cellulose), grasses may substitute Si for these components when carbon is limited. Indeed, high Si uptake grasses evolved in the Miocene when atmospheric CO2 concentration was much lower than present levels. It is, however, unknown how pre-industrial CO2 concentrations affect Si accumulation in grasses. Using Brachypodium distachyon, we hydroponically manipulated Si-supply (0.0, 0.5, 1, 1.5, 2 mM) and grew plants under Miocene (200 ppm) and Anthropocene levels of CO2 comprising ambient (410 ppm) and elevated (640 ppm) CO2 concentrations. We showed that regardless of Si treatments, the Miocene CO2 levels increased foliar Si concentrations by 47% and 56% relative to plants grown under ambient and elevated CO2, respectively. This is owing to higher accumulation overall, but also the reallocation of Si from the roots into the shoots. Our results suggest that grasses may accumulate high Si concentrations in foliage when carbon is less available (i.e. pre-industrial CO2 levels) but this is likely to decline under future climate change scenarios, potentially leaving grasses more susceptible to environmental stresses.
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Affiliation(s)
- Fikadu N Biru
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales 2751, Australia.,College of Agriculture and Veterinary Medicine, Jimma University, Jimma 307, Ethiopia
| | - Christopher I Cazzonelli
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales 2751, Australia
| | - Rivka Elbaum
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales 2751, Australia
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16
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Zancajo VMR, Lindtner T, Eisele M, Huber AJ, Elbaum R, Kneipp J. FTIR Nanospectroscopy Shows Molecular Structures of Plant Biominerals and Cell Walls. Anal Chem 2020; 92:13694-13701. [PMID: 32847355 DOI: 10.1021/acs.analchem.0c00271] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Plant tissues are complex composite structures of organic and inorganic components whose function relies on molecular heterogeneity at the nanometer scale. Scattering-type near-field optical microscopy (s-SNOM) in the mid-infrared (IR) region is used here to collect IR nanospectra from both fixed and native plant samples. We compared structures of chemically extracted silica bodies (phytoliths) to silicified and nonsilicified cell walls prepared as a flat block of epoxy-embedded awns of wheat (Triticum turgidum), thin sections of native epidermis cells from sorghum (Sorghum bicolor) comprising silica phytoliths, and isolated cells from awns of oats (Avena sterilis). The correlation of the scanning-probe IR images and the mechanical phase image enables a combined probing of mechanical material properties together with the chemical composition and structure of both the cell walls and the phytolith structures. The data reveal a structural heterogeneity of the different silica bodies in situ, as well as different compositions and crystallinities of cell wall components. In conclusion, IR nanospectroscopy is suggested as an ideal tool for studies of native plant materials of varied origins and preparations and could be applied to other inorganic-organic hybrid materials.
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Affiliation(s)
- Victor M R Zancajo
- School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, 12489 Berlin, Germany.,Chemistry Department, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany.,BAM Federal Institute for Materials Research and Testing, 12489 Berlin, Germany
| | - Tom Lindtner
- School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, 12489 Berlin, Germany.,Chemistry Department, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany
| | - Max Eisele
- Neaspec GmbH, Eglfinger Weg 2, D-85540 Munich-Haar, Germany
| | | | - Rivka Elbaum
- School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, 12489 Berlin, Germany.,The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Janina Kneipp
- School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, 12489 Berlin, Germany.,Chemistry Department, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany
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17
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Hodson MJ, Song Z, Ball TB, Elbaum R, Struyf E. Editorial: Frontiers in Phytolith Research. Front Plant Sci 2020; 11:454. [PMID: 32362906 PMCID: PMC7180188 DOI: 10.3389/fpls.2020.00454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Affiliation(s)
- Martin J. Hodson
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, United Kingdom
| | - Zhaoliang Song
- Institute of the Surface-Earth System Science, Tianjin University, Tianjin, China
| | - Terry B. Ball
- Department of Ancient Scripture, Brigham Young University, Provo, UT, United States
| | - Rivka Elbaum
- R.H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Eric Struyf
- Department of Biology, Global Change Ecology Centre, University of Antwerp, Wilrijk, Belgium
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18
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Zancajo VMR, Diehn S, Filiba N, Goobes G, Kneipp J, Elbaum R. Spectroscopic Discrimination of Sorghum Silica Phytoliths. Front Plant Sci 2019; 10:1571. [PMID: 31921236 PMCID: PMC6917640 DOI: 10.3389/fpls.2019.01571] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 11/11/2019] [Indexed: 05/09/2023]
Abstract
Grasses accumulate silicon in the form of silicic acid, which is precipitated as amorphous silica in microscopic particles termed phytoliths. These particles comprise a variety of morphologies according to the cell type in which the silica was deposited. Despite the evident morphological differences, phytolith chemistry has mostly been analysed in bulk samples, neglecting differences between the varied types formed in the same species. In this work, we extracted leaf phytoliths from mature plants of Sorghum bicolor (L.) Moench. Using solid state NMR and thermogravimetric analysis, we show that the extraction methods alter greatly the silica molecular structure, its condensation degree and the trapped organic matter. Measurements of individual phytoliths by Raman and synchrotron FTIR microspectroscopies in combination with multivariate analysis separated bilobate silica cells from prickles and long cells, based on the silica molecular structures and the fraction and composition of occluded organic matter. The variations in structure and composition of sorghum phytoliths suggest that the biological pathways leading to silica deposition vary between these cell types.
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Affiliation(s)
- Victor M. R. Zancajo
- School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, Berlin, Germany
- Chemistry Department, Humboldt-Universität zu Berlin, Berlin, Germany
- BAM Federal Institute for Materials Research and Testing, Berlin, Germany
- *Correspondence: Victor M. R. Zancajo, ; Janina Kneipp, ; Rivka Elbaum,
| | - Sabrina Diehn
- Chemistry Department, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Nurit Filiba
- Department of Chemistry, Bar Ilan University, Ramat Gan, Israel
| | - Gil Goobes
- Department of Chemistry, Bar Ilan University, Ramat Gan, Israel
| | - Janina Kneipp
- School of Analytical Sciences Adlershof (SALSA), Humboldt-Universität zu Berlin, Berlin, Germany
- Chemistry Department, Humboldt-Universität zu Berlin, Berlin, Germany
- BAM Federal Institute for Materials Research and Testing, Berlin, Germany
- *Correspondence: Victor M. R. Zancajo, ; Janina Kneipp, ; Rivka Elbaum,
| | - Rivka Elbaum
- R. H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
- *Correspondence: Victor M. R. Zancajo, ; Janina Kneipp, ; Rivka Elbaum,
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19
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Heiner Z, Zeise I, Elbaum R, Kneipp J. Insight into plant cell wall chemistry and structure by combination of multiphoton microscopy with Raman imaging. J Biophotonics 2018; 11:e201700164. [PMID: 29024576 DOI: 10.1002/jbio.201700164] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/08/2017] [Accepted: 10/10/2017] [Indexed: 06/07/2023]
Abstract
Spontaneous Raman scattering microspectroscopy, second harmonic generation (SHG) and 2-photon excited fluorescence (2PF) were used in combination to characterize the morphology together with the chemical composition of the cell wall in native plant tissues. As the data obtained with unstained sections of Sorghum bicolor root and leaf tissues illustrate, nonresonant as well as pre-resonant Raman microscopy in combination with hyperspectral analysis reveals details about the distribution and composition of the major cell wall constituents. Multivariate analysis of the Raman data allows separation of different tissue regions, specifically the endodermis, xylem and lumen. The orientation of cellulose microfibrils is obtained from polarization-resolved SHG signals. Furthermore, 2-photon autofluorescence images can be used to image lignification. The combined compositional, morphological and orientational information in the proposed coupling of SHG, Raman imaging and 2PF presents an extension of existing vibrational microspectroscopic imaging and multiphoton microscopic approaches not only for plant tissues.
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Affiliation(s)
- Zsuzsanna Heiner
- Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany
- SALSA School of Analytical Sciences Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Ingrid Zeise
- Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Rivka Elbaum
- The Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Janina Kneipp
- Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany
- SALSA School of Analytical Sciences Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
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20
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Kumar S, Elbaum R. Interplay between silica deposition and viability during the life span of sorghum silica cells. New Phytol 2018; 217:1137-1145. [PMID: 29058309 DOI: 10.1111/nph.14867] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 09/29/2017] [Indexed: 05/24/2023]
Abstract
Silica cells are specialized epidermal cells found on both surfaces of grass leaves, with almost the entire lumen filled with solid silica. The mechanism precipitating silicic acid into silica is not known. Here we investigate this process in sorghum (Sorghum bicolor) leaves. Using fluorescent confocal microscopy, we followed silica cells' ontogeny, aiming to understand the fate of vacuoles and nuclei. Correlating the confocal and scanning electron microscopy, we timed the initiation of silica deposition in relation to cell's viability. Contrary to earlier reports, silica cells did not lose their nucleus before silica deposition. Vacuoles in silica cells did not concentrate silicic acid. Instead, postmaturation silicification initiated at the cell periphery in live cells. Less than 1% silica cells showed characteristics of programmed cell death in the cell maturation zone. In fully elongated mature leaves, 2.4% of silica cells were nonsilicified and 1.6% were partially silicified. Silica deposition occurs in the paramural space of live silica cells. The mineral does not kill the cells. Instead, silica cells are genetically programmed to undergo cell death independent of silicification. Fully silicified cells seem to have nonsilicified voids containing membrane remains after the completion of the cell death processes.
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Affiliation(s)
- Santosh Kumar
- R. H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Rivka Elbaum
- R. H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
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21
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Soukup M, Martinka M, Bosnić D, Čaplovičová M, Elbaum R, Lux A. Formation of silica aggregates in sorghum root endodermis is predetermined by cell wall architecture and development. Ann Bot 2017; 120:739-753. [PMID: 28651339 PMCID: PMC5714252 DOI: 10.1093/aob/mcx060] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 03/13/2017] [Accepted: 04/14/2017] [Indexed: 05/18/2023]
Abstract
Background and Aims Deposition of silica in plant cell walls improves their mechanical properties and helps plants to withstand various stress conditions. Its mechanism is still not understood and silica-cell wall interactions are elusive. The objective of this study was to investigate the effect of silica deposition on the development and structure of sorghum root endodermis and to identify the cell wall components involved in silicification. Methods Sorghum bicolor seedlings were grown hydroponically with (Si+) or without (Si-) silicon supplementation. Primary roots were used to investigate the transcription of silicon transporters by quantitative RT-PCR. Silica aggregation was induced also under in vitro conditions in detached root segments. The development and architecture of endodermal cell walls were analysed by histochemistry, microscopy and Raman spectroscopy. Water retention capability was compared between silicified and non-silicified roots. Raman spectroscopy analyses of isolated silica aggregates were also carried out. Key Results Active uptake of silicic acid is provided at the root apex, where silicon transporters Lsi1 and Lsi2 are expressed. The locations of silica aggregation are established during the development of tertiary endodermal cell walls, even in the absence of silicon. Silica aggregation takes place in non-lignified spots in the endodermal cell walls, which progressively accumulate silicic acid, and its condensation initiates at arabinoxylan-ferulic acid complexes. Silicification does not support root water retention capability; however, it decreases root growth inhibition imposed by desiccation. Conclusion A model is proposed in which the formation of silica aggregates in sorghum roots is predetermined by a modified cell wall architecture and takes place as governed by endodermal development. The interaction with silica is provided by arabinoxylan-ferulic acid complexes and interferes with further deposition of lignin. Due to contrasting hydrophobicity, silicification and lignification do not represent functionally equivalent modifications of plant cell walls.
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Affiliation(s)
- Milan Soukup
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovicova 6, 84215 Bratislava, Slovak Republic
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100 Rehovot, Israel
| | - Michal Martinka
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovicova 6, 84215 Bratislava, Slovak Republic
| | - Dragana Bosnić
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010 Belgrade, Serbia
| | - Mária Čaplovičová
- Department of Geology of Mineral Deposits, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovicova 6, 842 15 Bratislava, Slovak Republic
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100 Rehovot, Israel
| | - Alexander Lux
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovicova 6, 84215 Bratislava, Slovak Republic
- Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 84538 Bratislava, Slovak Republic
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22
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Markovich O, Steiner E, Kouřil Š, Tarkowski P, Aharoni A, Elbaum R. Silicon promotes cytokinin biosynthesis and delays senescence in Arabidopsis and Sorghum. Plant Cell Environ 2017; 40:1189-1196. [PMID: 28102542 DOI: 10.1111/pce.12913] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/09/2017] [Accepted: 01/15/2017] [Indexed: 05/18/2023]
Abstract
Silicate minerals are dominant soil components. Thus, plant roots are constantly exposed to silicic acid. High silicon intake, enabled by root silicon transporters, correlates with increased tolerance to many biotic and abiotic stresses. However, the underlying protection mechanisms are largely unknown. Here, we tested the hypothesis that silicon interacts with the plant hormones, and specifically, that silicic acid intake increases cytokinin biosynthesis. The reaction of sorghum (Sorghum bicolor) and Arabidopsis plants, modified to absorb high versus low amounts of silicon, to dark-induced senescence was monitored, by quantifying expression levels of genes along the senescence pathway and measuring tissue cytokinin levels. In both species, detached leaves with high silicon content senesced more slowly than leaves that were not exposed to silicic acid. Expression levels of genes along the senescence pathway suggested increased cytokinin biosynthesis with silicon exposure. Mass spectrometry measurements of cytokinin suggested a positive correlation between silicon exposure and active cytokinin concentrations. Our results indicate a similar reaction to silicon treatment in distantly related plants, proposing a general function of silicon as a stress reliever, acting via increased cytokinin biosynthesis.
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Affiliation(s)
- Oshry Markovich
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Evyatar Steiner
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | - Štěpán Kouřil
- Centre of the Region Haná for Biotechnological and Agricultural Research, Central Laboratories and Research Support, Faculty of Science, Palacký University, Šlechtitelů 27, 78371, Olomouc, Czech Republic
| | - Petr Tarkowski
- Centre of the Region Haná for Biotechnological and Agricultural Research, Central Laboratories and Research Support, Faculty of Science, Palacký University, Šlechtitelů 27, 78371, Olomouc, Czech Republic
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Genetic Resources for Vegetables, Medicinal and Special Plants, Crop Research Institute, Šlechtitelů 27, 78371, Olomouc, Czech Republic
| | - Asaph Aharoni
- Department of Plant and Environmental Science, The Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Rivka Elbaum
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
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23
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Kumar S, Soukup M, Elbaum R. Silicification in Grasses: Variation between Different Cell Types. Front Plant Sci 2017; 8:438. [PMID: 28400787 PMCID: PMC5368260 DOI: 10.3389/fpls.2017.00438] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 03/14/2017] [Indexed: 05/23/2023]
Abstract
Plants take up silicon as mono-silicic acid, which is released to soil by the weathering of silicate minerals. Silicic acid can be taken up by plant roots passively or actively, and later it is deposited in its polymerized form as amorphous hydrated silica. Major silica depositions in grasses occur in root endodermis, leaf epidermal cells, and outer epidermal cells of inflorescence bracts. Debates are rife about the mechanism of silica deposition, and two contrasting scenarios are often proposed to explain it. According to the passive mode of silicification, silica deposition is a result of silicic acid condensation due to dehydration, such as during transpirational loss of water from the aboveground organs. In general, silicification and transpiration are positively correlated, and continued silicification is sometimes observed after cell and tissue maturity. The other mode of silicification proposes the involvement of some biological factors, and is based on observations that silicification is not necessarily coupled with transpiration. Here, we review evidence for both mechanisms of silicification, and propose that the deposition mechanism is specific to the cell type. Considering all the cell types together, our conclusion is that grass silica deposition can be divided into three modes: spontaneous cell wall silicification, directed cell wall silicification, and directed paramural silicification in silica cells.
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Affiliation(s)
| | | | - Rivka Elbaum
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture The Hebrew University of JerusalemRehovot, Israel
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24
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Kumar S, Milstein Y, Brami Y, Elbaum M, Elbaum R. Mechanism of silica deposition in sorghum silica cells. New Phytol 2017; 213:791-798. [PMID: 27621091 DOI: 10.1111/nph.14173] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 07/27/2016] [Indexed: 05/03/2023]
Abstract
Grasses take up silicic acid from soil and deposit it in their leaves as solid silica. This mineral, comprising 1-10% of the grass dry weight, improves plants' tolerance to various stresses. The mechanisms promoting stress tolerance are mostly unknown, and even the mineralization process is poorly understood. To study leaf mineralization in sorghum (Sorghum bicolor), we followed silica deposition in epidermal silica cells by in situ charring and air-scanning electron microscopy. Our findings were correlated to the viability of silica cells tested by fluorescein diacetate staining. We compared our results to a sorghum mutant defective in root uptake of silicic acid. We showed that the leaf silicification in these plants is intact by detecting normal mineralization in leaves exposed to silicic acid. Silica cells were viable while condensing silicic acid into silica. The controlled mineral deposition was independent of water evapotranspiration. Fluorescence recovery after photobleaching suggested that the forming mineral conformed to the cellulosic cell wall, leaving the cytoplasm well connected to neighboring cells. As the silicified wall thickened, the functional cytoplasm shrunk into a very small space. These results imply that leaf silica deposition is an active, physiologically regulated process as opposed to a simple precipitation.
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Affiliation(s)
- Santosh Kumar
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
| | | | | | - Michael Elbaum
- Department of Materials and Interfaces, The Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Rivka Elbaum
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 7610001, Israel
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Kumar S, Elbaum R. Estimation of Silica Cell Silicification Level in Grass Leaves Using in situ Charring Method. Bio Protoc 2017; 7:e2607. [DOI: 10.21769/bioprotoc.2607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/22/2017] [Accepted: 09/23/2017] [Indexed: 11/02/2022] Open
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Shtein I, Elbaum R, Bar-On B. The Hygroscopic Opening of Sesame Fruits Is Induced by a Functionally Graded Pericarp Architecture. Front Plant Sci 2016; 7:1501. [PMID: 27777579 PMCID: PMC5056167 DOI: 10.3389/fpls.2016.01501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 09/21/2016] [Indexed: 05/27/2023]
Abstract
To enhance the distribution of their seeds, plants often utilize hygroscopic deformations that actuate dispersal mechanisms. Such movements are based on desiccation-induced shrinkage of tissues in predefined directions. The basic hygroscopic deformations are typically actuated by a bi-layer configuration, in which shrinking of an active tissue layer is resisted by a stiff layer, generating a set of basic movements including bending, coiling, and twisting. In this study, we investigate a new type of functionally graded hygroscopic movement in the fruit (capsule) of sesame (Sesamum indicum L.). Microscopic observations of the capsules showed that the inner stiff endocarp layer is built of a bilayer of transverse (i.e., circumferential) and longitudinal fiber cells with the layers positioned in a semi-circle, one inside the other. The outer mesocarp layer is made of soft parenchyma cells. The thickness of the fibrous layers and of the mesocarp exhibits a graded architecture, with gradual changes in their thickness around the capsule circumference. The cellulose microfibrils in the fiber cell walls are lying parallel to the cell long axis, rendering them stiff. The outer mesocarp layer contracted by 300% as it dried. Removal of this outer layer inhibited the opening movement, indicating that it is the active tissue. A biomechanical hygro-elastic model based on the relative thicknesses of the layers successfully simulated the opening curvature. Our findings suggest that the sesame capsules possess a functionally graded architecture, which promotes a non-uniform double-curvature hygroscopic bending movement. In contrast to other hygroscopic organs described in the literature, the sesame capsule actuating and resisting tissues are not uniform throughout the device, but changing gradually. This newly described mechanism can be exploited in bio-inspired designs of novel actuating platforms.
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Affiliation(s)
- Ilana Shtein
- Department of Mechanical Engineering, Ben-Gurion University of the NegevBeer-Sheva, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of JerusalemRehovot, Israel
| | - Benny Bar-On
- Department of Mechanical Engineering, Ben-Gurion University of the NegevBeer-Sheva, Israel
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Fridman Y, Holland N, Elbaum R, Savaldi-Goldstein S. High Resolution Quantification of Crystalline Cellulose Accumulation in Arabidopsis Roots to Monitor Tissue-specific Cell Wall Modifications. J Vis Exp 2016. [PMID: 27214583 DOI: 10.3791/53707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Plant cells are surrounded by a cell wall, the composition of which determines their final size and shape. The cell wall is composed of a complex matrix containing polysaccharides that include cellulose microfibrils that form both crystalline structures and cellulose chains of amorphous organization. The orientation of the cellulose fibers and their concentrations dictate the mechanical properties of the cell. Several methods are used to determine the levels of crystalline cellulose, each bringing both advantages and limitations. Some can distinguish the proportion of crystalline regions within the total cellulose. However, they are limited to whole-organ analyses that are deficient in spatiotemporal information. Others relying on live imaging, are limited by the use of imprecise dyes. Here, we report a sensitive polarized light-based system for specific quantification of relative light retardance, representing crystalline cellulose accumulation in cross sections of Arabidopsis thaliana roots. In this method, the cellular resolution and anatomical data are maintained, enabling direct comparisons between the different tissues composing the growing root. This approach opens a new analytical dimension, shedding light on the link between cell wall composition, cellular behavior and whole-organ growth.
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Affiliation(s)
- Yulia Fridman
- Faculty of Biology, Technion-Israel Institute of Technology;
| | - Neta Holland
- Faculty of Biology, Technion-Israel Institute of Technology
| | - Rivka Elbaum
- Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem
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Nida H, Blum S, Zielinski D, Srivastava DA, Elbaum R, Xin Z, Erlich Y, Fridman E, Shental N. Highly efficient de novo mutant identification in a Sorghum bicolor TILLING population using the ComSeq approach. Plant J 2016; 86:349-359. [PMID: 26959378 DOI: 10.1111/tpj.13161] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/10/2016] [Accepted: 03/01/2016] [Indexed: 05/29/2023]
Abstract
Screening large populations for carriers of known or de novo rare single nucleotide polymorphisms (SNPs) is required both in Targeting induced local lesions in genomes (TILLING) experiments in plants and in screening of human populations. We previously suggested an approach that combines the mathematical field of compressed sensing with next-generation sequencing to allow such large-scale screening. Based on pooled measurements, this method identifies multiple carriers of heterozygous or homozygous rare alleles while using only a small fraction of resources. Its rigorous mathematical foundations allow scalable and robust detection, and provide error correction and resilience to experimental noise. Here we present a large-scale experimental demonstration of our computational approach, in which we targeted a TILLING population of 1024 Sorghum bicolor lines to detect carriers of de novo SNPs whose frequency was less than 0.1%, using only 48 pools. Subsequent validation confirmed that all detected lines were indeed carriers of the predicted mutations. This novel approach provides a highly cost-effective and robust tool for biologists and breeders to allow identification of novel alleles and subsequent functional analysis.
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Affiliation(s)
- Habte Nida
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Shula Blum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Dina Zielinski
- New York Genome Center, 101 Avenue of the Americas, New York, NY, USA
| | - Dhruv A Srivastava
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
- Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Zhanguo Xin
- Plant Stress and Germplasm Development Unit, US Department of Agriculture/Agricultural Research Service, Lubbock, TX, USA
| | - Yaniv Erlich
- New York Genome Center, 101 Avenue of the Americas, New York, NY, USA
- Department of Computer Science, Fu Foundation School of Engineering, Columbia University, New York, NY, USA
- Center for Computational Biology and Bioinformatics, Columbia University, New York, NY, USA
| | - Eyal Fridman
- Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
| | - Noam Shental
- Department of Mathematics and Computer Science, The Open University of Israel, Raanana, Israel
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29
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Vulavala VKR, Elbaum R, Yermiyahu U, Fogelman E, Kumar A, Ginzberg I. Silicon fertilization of potato: expression of putative transporters and tuber skin quality. Planta 2016; 243:217-29. [PMID: 26384982 DOI: 10.1007/s00425-015-2401-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 08/31/2015] [Indexed: 05/06/2023]
Abstract
A silicon transporter homolog was upregulated by Si fertilization and drought in potato roots and leaves. High Si in tuber skin resulted in anatomical and compositional changes suggesting delayed skin maturation. Silicon (Si) fertilization has beneficial effects on plant resistance to biotic and abiotic stresses. Potatoes, low Si accumulators, are susceptible to yield loss due to suboptimal growth conditions; thus Si fertilization may contribute to crop improvement. The effect of Si fertilization on transcript levels of putative transporters, Si uptake and tuber quality was studied in potatoes grown in a glasshouse and fertilized with sodium silicate, under normal and drought-stress conditions. Anatomical studies and Raman spectroscopic analyses of tuber skin were conducted. A putative transporter, StLsi1, with conserved amino acid domains for Si transport, was isolated. The StLsi1 transcript was detected in roots and leaves and its level increased twofold following Si fertilization, and about fivefold in leaves upon Si × drought interaction. Nevertheless, increased Si accumulation was detected only in tuber peel of Si-fertilized plants--probably due to passive movement of Si from the soil solution--where it modified skin cell morphology and cell-wall composition. Compared to controls, skin cell area was greater, suberin biosynthetic genes were upregulated and skin cell walls were enriched with oxidized aromatic moieties suggesting enhanced lignification and suberization. The accumulating data suggest delayed tuber skin maturation following Si fertilization. Despite StLsi1 upregulation, low accumulation of Si in roots and leaves may result from low transport activity. Study of Si metabolism in potato, a major staple food, would contribute to the improvement of other low Si crops to ensure food security under changing climate.
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Affiliation(s)
- Vijaya K R Vulavala
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, PO Box 6, 5025001, Bet Dagan, Israel
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Hebrew University of Jerusalem, PO Box 12, 7610001, Rehovot, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Hebrew University of Jerusalem, PO Box 12, 7610001, Rehovot, Israel
| | - Uri Yermiyahu
- Institute of Soil and Water, Agricultural Research Organization, Gilat Center, Negev, 85280, Israel
| | - Edna Fogelman
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, PO Box 6, 5025001, Bet Dagan, Israel
| | - Akhilesh Kumar
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, PO Box 6, 5025001, Bet Dagan, Israel
| | - Idit Ginzberg
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, PO Box 6, 5025001, Bet Dagan, Israel.
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Abu-Abied M, Rogovoy Stelmakh O, Mordehaev I, Grumberg M, Elbaum R, Wasteneys GO, Sadot E. Dissecting the contribution of microtubule behaviour in adventitious root induction. J Exp Bot 2015; 66:2813-24. [PMID: 25788735 PMCID: PMC4986881 DOI: 10.1093/jxb/erv097] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Induction of adventitious roots (ARs) in recalcitrant plants often culminates in cell division and callus formation rather than root differentiation. Evidence is provided here to suggest that microtubules (MTs) play a role in the shift from cell division to cell differentiation during AR induction. First, it was found that fewer ARs form in the temperature-sensitive mutant mor1-1, in which the MT-associated protein MOR1 is mutated, and in bot1-1, in which the MT-severing protein katanin is mutated. In the two latter mutants, MT dynamics and form are perturbed. By contrast, the number of ARs increased in RIC1-OX3 plants, in which MT bundling is enhanced and katanin is activated. In addition, any1 plants in which cell walls are perturbed made more ARs than wild-type plants. MT perturbations during AR induction in mor1-1 or in wild-type hypocotyls treated with oryzalin led to the formation of amorphous clusters of cells reminiscent of callus. In these cells a specific pattern of polarized light retardation by the cell walls was lost. PIN1 polarization and auxin maxima were hampered and differentiation of the epidermis was inhibited. It is concluded that a fine-tuned crosstalk between MTs, cell walls, and auxin transport is required for proper AR induction.
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Affiliation(s)
- Mohamad Abu-Abied
- The Institute of Plant Sciences, The Volcani Center, ARO, PO Box 6, Bet-Dagan 50250, Israel
| | | | - Inna Mordehaev
- The Institute of Plant Sciences, The Volcani Center, ARO, PO Box 6, Bet-Dagan 50250, Israel
| | - Marina Grumberg
- The Institute of Plant Sciences, The Volcani Center, ARO, PO Box 6, Bet-Dagan 50250, Israel
| | - Rivka Elbaum
- The Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Geoffrey O Wasteneys
- Department of Botany, The University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada
| | - Einat Sadot
- The Institute of Plant Sciences, The Volcani Center, ARO, PO Box 6, Bet-Dagan 50250, Israel
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Ben-Tov D, Abraham Y, Stav S, Thompson K, Loraine A, Elbaum R, de Souza A, Pauly M, Kieber JJ, Harpaz-Saad S. COBRA-LIKE2, a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE family, plays a role in cellulose deposition in arabidopsis seed coat mucilage secretory cells. Plant Physiol 2015; 167:711-24. [PMID: 25583925 PMCID: PMC4347734 DOI: 10.1104/pp.114.240671] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 12/24/2014] [Indexed: 05/17/2023]
Abstract
Differentiation of the maternally derived seed coat epidermal cells into mucilage secretory cells is a common adaptation in angiosperms. Recent studies identified cellulose as an important component of seed mucilage in various species. Cellulose is deposited as a set of rays that radiate from the seed upon mucilage extrusion, serving to anchor the pectic component of seed mucilage to the seed surface. Using transcriptome data encompassing the course of seed development, we identified COBRA-LIKE2 (COBL2), a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE gene family in Arabidopsis (Arabidopsis thaliana), as coexpressed with other genes involved in cellulose deposition in mucilage secretory cells. Disruption of the COBL2 gene results in substantial reduction in the rays of cellulose present in seed mucilage, along with an increased solubility of the pectic component of the mucilage. Light birefringence demonstrates a substantial decrease in crystalline cellulose deposition into the cellulosic rays of the cobl2 mutants. Moreover, crystalline cellulose deposition into the radial cell walls and the columella appears substantially compromised, as demonstrated by scanning electron microscopy and in situ quantification of light birefringence. Overall, the cobl2 mutants display about 40% reduction in whole-seed crystalline cellulose content compared with the wild type. These data establish that COBL2 plays a role in the deposition of crystalline cellulose into various secondary cell wall structures during seed coat epidermal cell differentiation.
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Affiliation(s)
- Daniela Ben-Tov
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
| | - Yael Abraham
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
| | - Shira Stav
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
| | - Kevin Thompson
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
| | - Ann Loraine
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
| | - Rivka Elbaum
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
| | - Amancio de Souza
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
| | - Markus Pauly
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
| | - Joseph J Kieber
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
| | - Smadar Harpaz-Saad
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, Rehovot 76100, Israel (D.B.-T., Y.A., R.E., S.H.-S.);Department of Bioinformatics and Genomics, University of North Carolina, Kannapolis, North Carolina 28081 (S.S., K.T., A.L.);Energy Biosciences Institute (A.d.S., M.P.) and Department of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720; andBiology Department, University of North Carolina, Chapel Hill, North Carolina 27599 (J.J.K.)
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Elbaum R, Abraham Y. Insights into the microstructures of hygroscopic movement in plant seed dispersal. Plant Sci 2014; 223:124-33. [PMID: 24767122 DOI: 10.1016/j.plantsci.2014.03.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 02/12/2014] [Accepted: 03/16/2014] [Indexed: 05/08/2023]
Abstract
As non-motile organisms, plants develop means to spread their progenies. Hygroscopic movement is a very common mechanism employed in seed dispersal. This type of movement is created when the tissue desiccates and the cell walls dry and shrink. A contraction force develops, the direction and strength of which depends on the architecture of the tissue. This force may be utilized for a simple release of seeds, their catapultion, and for pushing seeds along the soil to a germination locus. We review the formation of a bend, a twist and a coil within various dispersal apparatuses as a reaction to the dehydration of the tissue. We compare the microscopic structures of hygroscopic devices supporting slow or fast movement, adaptations to dry or wet climates, and single use versus repeated movement. We discuss the development of the disconnecting tissues in relation to the development of a hygroscopic mechanism. As plant cultivation is dependent on seed dispersal control, we demonstrate that during the domestication of sesame and wheat, seed dispersal is avoided not due to a defective hygroscopic tissue, but rather a missing dehiscence tissue. Seed dispersal is a crucial stage in the life cycle of plants. Thus, hygroscopic movement plays a central part in plant ecology and agriculture.
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Affiliation(s)
- Rivka Elbaum
- RH Smith Institute for Plant Sciences and genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 7010001, Israel.
| | - Yael Abraham
- RH Smith Institute for Plant Sciences and genetics in Agriculture, Hebrew University of Jerusalem, Rehovot 7010001, Israel
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Abstract
Coherent plant growth requires spatial integration of hormonal pathways and cell wall remodeling activities. However, the mechanisms governing sensitivity to hormones and how cell wall structure integrates with hormonal effects are poorly understood. We found that coordination between two types of epidermal root cells, hair and nonhair cells, establishes root sensitivity to the plant hormones brassinosteroids (BRs). While expression of the BR receptor BRASSINOSTEROID-INSENSITIVE1 (BRI1) in hair cells promotes cell elongation in all tissues, its high relative expression in nonhair cells is inhibitory. Elevated ethylene and deposition of crystalline cellulose underlie the inhibitory effect of BRI1. We propose that the relative spatial distribution of BRI1, and not its absolute level, fine-tunes growth.
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Affiliation(s)
- Yulia Fridman
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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Abraham Y, Elbaum R. Hygroscopic movements in Geraniaceae: the structural variations that are responsible for coiling or bending. New Phytol 2013; 199:584-594. [PMID: 23574364 DOI: 10.1111/nph.12254] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 03/04/2013] [Indexed: 05/08/2023]
Abstract
The family Geraniaceae is characterized by a beak-like fruit, consisting of five seeds appended by a tapering awn. The awns exhibit coiling or bending hygroscopic movement as part of the seed dispersal strategy. Here we explain the variation in the hygroscopic reaction based on structural principles. We examined five representative species from three genera: Erodium, Geranium, and Pelargonium. Using X-ray diffraction, and electron and polarized light microscopy, we measured the cellulose microfibril angles in relation to the cell and cellulose helix axes. The behavior of separated single cells during dehydration was also examined. A bi-layered structure characterizes all the representative genera studied, with a hygroscopically contracting inner layer, and a stiff outer layer. We found that the cellulose arrangement in the inner layer is responsible for the type of awn deformation (coiling or bending). In three of the five awns examined, we identified an additional coiling outer sublayer, which adds coiling deformation to the awn. We divide the movements into three types: bending, coiling, and coiled-bending. All movement types are found in the Geranium genus. These characteristics are of importance for understanding the evolution of seed dispersal mechanisms in the Geraniaceae family.
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Affiliation(s)
- Yael Abraham
- The Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Rivka Elbaum
- The Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
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Abraham Y, Elbaum R. Quantification of microfibril angle in secondary cell walls at subcellular resolution by means of polarized light microscopy. New Phytol 2013; 197:1012-1019. [PMID: 23240639 DOI: 10.1111/nph.12070] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 10/27/2012] [Indexed: 05/08/2023]
Abstract
The cell walls constitute the mechanical support of plants. Crystalline cellulose building the walls forms rigid microfibrils that set the stiffness of the cell and the direction in which it expands during growth. Therefore, the determination of the directions of the microfibrils is important in both mechanical and developmental assays. We adapted polarized light microscopy to estimate the cellulose microfibril orientations at subcellular resolution. The optical information supplements X-ray scattering data, Raman microspectroscopy, and electron microscopy. We analyzed samples from three plant tissues: cells from an Araucaria excels branch, in which we revealed lower cellulose density in regions where the cell wall curvature becomes bigger, namely, the cell wall corners; a wheat (Triticum turgidum) awn's hygroscopically active region, which revealed a gradient in the cellulose microfibril angles that spans across four cell rows; and a stork's bill's (Erodium gruinum) coiling awn, which revealed that the cellulose in the cell wall is organized in two orientations seamed together, rather than in a continuous helix. The unique spatial information is easily obtained from microscopic specimens and further illuminates new aspects in the mechanical tissues.
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Affiliation(s)
- Yael Abraham
- The Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Rivka Elbaum
- The Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
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Zickler GA, Ruffoni D, Dunlop JWC, Elbaum R, Weinkamer R, Fratzl P, Antretter T. Finite element modeling of the cyclic wetting mechanism in the active part of wheat awns. Biointerphases 2012; 7:42. [PMID: 22791359 DOI: 10.1007/s13758-012-0042-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 06/15/2012] [Indexed: 11/28/2022] Open
Abstract
Many plant tissues and organs are capable of moving due to changes in the humidity of the environment, such as the opening of the seed capsule of the ice plant and the opening of the pine cone. These are fascinating examples for the materials engineer, as these tissues are non-living and move solely through the differential swelling of anisotropic tissues and in principle may serve as examples for the bio-inspired design of artificial actuators. In this paper, we model the microstructure of the wild wheat awn (Triticum turgidum ssp. dicoccoides) by finite elements, especially focusing on the specific microscopic features of the active part of the awn. Based on earlier experimental findings, cell walls are modeled as multilayered cylindrical tubes with alternating cellulose fiber orientation in successive layers. It is shown that swelling upon hydration of this system leads to the formation of gaps between the layers, which could act as valves, thus enabling the entry of water into the cell wall. This supports the hypothesis that this plywood-like arrangement of cellulose fibrils enhances the effect of ambient humidity by accelerated water or vapor diffusion along the gaps. The finite element model shows that a certain distribution of axially and tangentially oriented fibers is necessary to generate sufficient tensile stresses within the cell wall to open nanometer-sized gaps between cell wall layers.
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Affiliation(s)
- Gerald A Zickler
- Institute for Mechanics, Montanuniversitaet Leoben, Leoben, Austria.
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Aharoni H, Abraham Y, Elbaum R, Sharon E, Kupferman R. Emergence of spontaneous twist and curvature in non-euclidean rods: application to Erodium plant cells. Phys Rev Lett 2012; 108:238106. [PMID: 23003997 DOI: 10.1103/physrevlett.108.238106] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/22/2012] [Indexed: 06/01/2023]
Abstract
We present a limiting model for thin non-euclidean elastic rods. Originating from the three-dimensional (3D) reference metric of the rod, which is determined by its internal material structure, we derive a 1D reduced rod theory. Specifically, we show how the spontaneous twist and curvature of a rod emerge from the reference metric derivatives. Thus, the model allows calculating the unconstrained equilibrium configuration of a thin rod directly from its internal structure. The model is applied to the study of cells from members of the Geraniaceae plant family and their configurational response to dehydration. We show how the geometrical arrangement of cellulose fibrils on the cell walls determines the helical shapes of isolated cells.
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Affiliation(s)
- Hillel Aharoni
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Abraham Y, Tamburu C, Klein E, Dunlop JWC, Fratzl P, Raviv U, Elbaum R. Tilted cellulose arrangement as a novel mechanism for hygroscopic coiling in the stork's bill awn. J R Soc Interface 2011; 9:640-7. [PMID: 21865252 DOI: 10.1098/rsif.2011.0395] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The sessile nature of plants demands the development of seed-dispersal mechanisms to establish new growing loci. Dispersal strategies of many species involve drying of the dispersal unit, which induces directed contraction and movement based on changing environmental humidity. The majority of researched hygroscopic dispersal mechanisms are based on a bilayered structure. Here, we investigate the motility of the stork's bill (Erodium) seeds that relies on the tightening and loosening of a helical awn to propel itself across the surface into a safe germination place. We show that this movement is based on a specialized single layer consisting of a mechanically uniform tissue. A cell wall structure with cellulose microfibrils arranged in an unusually tilted helix causes each cell to spiral. These cells generate a macroscopic coil by spiralling collectively. A simple model made from a thread embedded in an isotropic foam matrix shows that this cellulose arrangement is indeed sufficient to induce the spiralling of the cells.
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Affiliation(s)
- Yael Abraham
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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Bauer P, Elbaum R, Weiss IM. Calcium and silicon mineralization in land plants: transport, structure and function. Plant Sci 2011; 180:746-56. [PMID: 21497710 DOI: 10.1016/j.plantsci.2011.01.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 01/27/2011] [Accepted: 01/30/2011] [Indexed: 05/04/2023]
Abstract
Plant biomineralization involves calcium and silicon transport and mineralization. Respective analytical methods and case studies are listed. Calcium carbonate is deposited in cystoliths, calcium oxalate in idioblasts. Silicon is deposited in phytoliths. Biomineralization is a coordinated process.
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Affiliation(s)
- Petra Bauer
- Department Biosciences-Plant Biology, Saarland University, Campus A2.4, D-66123 Saarbrücken, Germany.
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Abstract
Awns are long, stiff filamentous extensions of glumes in many grasses. In wheat, awns contribute up to 40% of the grain's photosynthetic assimilates, and assist in seed dispersal. Awns accumulate silica in epidermal hairs and papillae, and silica has been positively associated with yield and environmental stress tolerance. Here, the awns of a set of domesticated wheat genotypes and their direct progenitor, Triticum turgidum ssp. dicoccoides were characterized. In addition, the silica concentration in awns was genetically dissected in a tetraploid wheat population of recombinant inbred lines (RILs) derived from a cross between durum wheat (cv. Langdon) and wild emmer (accession G18-16). Scanning electron micrographs revealed a continuous silica layer under the cuticle. Extended silicification was identified in the epidermis cell wall and in sclerenchyma cells near the vascular bundles, but not in the stomata, suggesting that an active process directs the soluble silica away from the water evaporation stream. The number of silicified cells was linearly correlated to silica concentration in dry weight (DW), suggesting cellular control over silicification. Domesticated wheat awns contained up to 19% silica per DW, as compared with 7% in the wild accessions, suggesting selection pressure associated with the domestication process. Six quantitative trait loci (QTLs) for silica were identified in the awns, with a LOD score of 3.7-6.3, three of which overlapped genomic regions that contribute to high grain protein. Localization of silica in the awns and identification of QTLs help illuminate mechanisms associated with silica metabolism in wheat.
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Affiliation(s)
- Zvi Peleg
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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Elbaum R, Gorb S, Fratzl P. Structures in the cell wall that enable hygroscopic movement of wheat awns. J Struct Biol 2008; 164:101-7. [PMID: 18625323 DOI: 10.1016/j.jsb.2008.06.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 06/17/2008] [Accepted: 06/18/2008] [Indexed: 11/28/2022]
Abstract
The dispersal unit of wild wheat bears two prominent filaments called awns. The awns bend as they dry and straighten in a damp environment. This hygroscopic movement is explained by the orientation of the cellulose fibrils that build the cell wall, as follows. The stiff fibrils are embedded in a soft hygroscopic matrix. When the cell wall dries, the matrix shrinks but the fibrils do not. Therefore, the cell wall contracts in a direction perpendicular to the fibril orientation. Using X-ray scattering we identified a region at the base of the awn that contains fibrils aligned in all directions. This is the active part, which contracts as it dries and pulls the awn to a bent position. Cryo-scanning electron microscopy revealed sequential laminas which are rotated to form a nano-scale plywood construction, implying planar local order within the global isotropy. Water molecules absorbed into the matrix probably cause large microscopic distortions by expanding neighboring layers in perpendicular directions. This is thought to cause opening of tiny gaps between fiber layers, to facilitate the exchange and the transport of water through the cell wall, and thereby to increase the sensitivity of the actuating unit to moderate changes in humidity.
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Affiliation(s)
- Rivka Elbaum
- Department of Plant Sciences, Weizmann Institute of Science, 76100 Rehovot, Israel.
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Abstract
The dispersal unit of wild wheat bears two pronounced awns that balance the unit as it falls. We discovered that the awns are also able to propel the seeds on and into the ground. The arrangement of cellulose fibrils causes bending of the awns with changes in humidity. Silicified hairs that cover the awns allow propulsion of the unit only in the direction of the seeds. This suggests that the dead tissue is analogous to a motor. Fueled by the daily humidity cycle, the awns induce the motility required for seed dispersal.
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Affiliation(s)
- Rivka Elbaum
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, Golm, Germany.
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Elbaum R, Tal E, Perets AI, Oron D, Ziskind D, Silberberg Y, Wagner HD. Dentin micro-architecture using harmonic generation microscopy. J Dent 2007; 35:150-5. [PMID: 16973251 DOI: 10.1016/j.jdent.2006.07.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Revised: 07/02/2006] [Accepted: 07/04/2006] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES We present a novel way to create high-resolution three-dimensional images of tooth dentin by harmonic generation scanning laser microscopy. METHODS The images were taken using a pulsed infrared laser. Three-dimensional reconstruction enables the visualization of individual tubules and the collagen fibrils mesh around them with an optical resolution of approximately 1 microm. RESULTS The images show micro-morphological details of the dentinal tubules as well as the collagen fibrils at a depth of up to about 200 microm. The data show that while collagen fibrils are organized in planes perpendicular to the tubules, close to the dentin enamel junction they lie also along the long axis of the tubules. CONCLUSIONS The unique 3D information opens the opportunity to study the collagen fibril arrangement in relation to the tubule orientation within the dentin matrix, and may be applied to study the micro-morphology of normal versus altered dentin.
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Affiliation(s)
- R Elbaum
- Department of Materials and Interfaces, The Weizmann Institute of Science, Rehovot 76100, Israel
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Quintart C, Elbaum R. [A case of isolated avulsion fracture of the posterior cruciate ligament in a child]. Rev Chir Orthop Reparatrice Appar Mot 1999; 85:617-20. [PMID: 10575724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
PURPOSE OF THE STUDY The authors report one case of isolated avulsion fracture of the tibial attachment of the posterior cruciate ligament. They recommend the use of 3D CT Scan to appreciate the size, the displacement of the bone fragment or the occurrence of comminuted fracture. MATERIAL AND METHOD A 12 years old girl was admitted for knee pain and swelling secondary to horse's hoof blow on the anterior aspect of the proximal tibia. Hemarthrosis, contusion of the anterior surface of the proximal tibia were present. Because of pain and swelling, the knee could not be examined with accuracy. Roentgenographic examination showed isolated avulsion fracture of the tibial attachment of the posterior cruciate ligament. 3D CT Scan confirmed the lesion. Bony fragment was displaced and was not comminuted. Approach through the popliteal fossa was used and bony fragment was screwed back into its bed. RESULTS Postoperatively, a long leg plaster of Paris was applied for 6 weeks. The patient was followed for 1.5 year. She returned to her previous occupation. There was no residual laxity. X ray confirmed fracture union. DISCUSSION Results of primary repair of interstitial posterior cruciate ligament tears were inconsistent. On the contrary, good functional results were obtained with surgically treated avulsion fracture of the posterior cruciate ligament. Displaced bony fragment will be fixed properly to its bed. 3D CT Scan appreciate the size, the displacement or the occurrence of comminuted fracture. Those informations help to define surgical procedure: screw, wire-suture or staple.
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Affiliation(s)
- C Quintart
- Département d'orthopédie traumatologie de l'A.H.E. Ixelles, Bruxelles
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Elbaum R, Royer M, Godart S. Radial club hand and Holt-Oram syndrome. Acta Chir Belg 1995; 95:229-36. [PMID: 7502621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The authors describe the case of a young African girl born with a radial club hand associated with a pedicled floating thumb, no other orthopaedic malformation was detected. A ventricular septal defect necessitated surgery in emergency. In front of such malformative association, the Holt-Oram syndrome has been evoked. The aim of this study has been to review the etiology and classification of this rather rare malformative association, as well as to describe the therapeutic attitudes and surgical techniques proposed by various authors towards the radial club hand (1, 3, 5, 6, 7, 12).
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Affiliation(s)
- R Elbaum
- Department of paediatric surgery, Centre Hospitalier Etterbeek-Ixelles, Brussels, Belgium
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Elbaum R, Remusat M, Brouillet JL. Biocompatibility of an enamel-dentin adhesive. Quintessence Int 1992; 23:773-82. [PMID: 1305294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
To assess the biocompatibility of a third-generation dentinal adhesive that uses a smear layer conditioner (Scotchbond 2), Class V cavities were prepared and restored in vivo, following a standardized protocol, in 32 human premolars to be extracted for orthodontic reasons. Histologic observation showed seven slight, five moderate, and one severe reaction short term, while 11 slight and three moderate reactions were observed long term. It appeared that the intensity of the reactions decreased with time. Bacteria were observed on only five teeth, and no correlation could be established between the presence of bacteria and the intensity of the reactions. It seemed that the conditioning of the smear layer, although it might have rendered the residual dentin more permeable, limited percolation phenomena by increasing adhesion. Although only one severe reaction was observed, it is mandatory in a clinical setting to place a protective lining near the pulp.
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Affiliation(s)
- R Elbaum
- Department of Operative Dentistry, University of Marseilles, Faculty of Dental Surgery, France
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Elbaum R, Pignoly C, Brouillet JL. A histologic study of the biocompatibility of a dentinal bonding system. Quintessence Int 1991; 22:901-10. [PMID: 1812514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
To assess the biocompatibility of an adhesive system, standard Class V cavities were prepared in vivo in human premolars that were to be extracted for orthodontic purposes. Histologic observation revealed that the Gluma Bond System elicited slight to severe pulpal responses, altered odontoblastic layers, and inhibited dentinogenesis. These alterations were observed after in vivo periods of up to 120 days. In this experiment, the dentinal adhesive was polymerized separately from the composite resin, a procedure not recommended by the manufacturer. This may explain the differences in the present results and those reported by the manufacturer.
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Affiliation(s)
- R Elbaum
- Department of Operative Dentistry, University of Marseilles, Faculty of Dental Surgery
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Pignoly C, Elbaum R, Koubi G. [Isolation of the operative field in esthetic restorative dentistry]. Clin Odontol 1990; 11:297-303. [PMID: 2135227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- C Pignoly
- Département d'Odontologie Conservatrice, Section Restauratrice, Faculté de Chirurgie Dentaire de Marseille
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50
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Godart S, Elbaum R. [Indications and technics in surgery of the spleen in children]. Rev Med Brux 1988; 9:32-5. [PMID: 3283900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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