A biomimetic platform for studying root-environment interaction

Abstract Aims Microstructure plays an important role in biological systems. Microstructural features are critical in the interaction between two biological organisms, for example, a microorganism and the surface of a plant. However, isolating the structural effect of the interaction from all other parameters is challenging when working directly with the natural system. Replicating microstructure of leaves was recently shown to be a powerful research tool for studying leaf-environment interaction. However, no such tool exists for roots. Roots present a special challenge because of their delicacy (specifically of root hairs) and their 3D structure. We aim at developing such a tool for roots. Methods Biomimetics use synthetic systems to mimic the structure of biological systems, enabling the isolation of structural function. Here we present a method which adapts tools from leaf microstructure replication to roots. We introduce new polymers for this replication. Results We find that Polyurethane methacrylate (PUMA) with fast UV curing gives a reliable replication of the tomato root surface microstructure. We show that our system is compatible with the pathogenic soilborne bacterium Ralstonia solanacearum. Conclusions This newly developed tool may be used to study the effect of microstructure, isolated from all other effects, on the interaction of roots with their environment.

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Cytological and histochemical characteristics of the axenic root surface of Alnus glutinosa

Canadian Journal of Botany ◽

10.1139/b86-296 ◽

1986 ◽

Vol 64 (10) ◽

pp. 2216-2226 ◽

Cited By ~ 9

Author(s):

Yves Prin ◽

Mireille Rougier

Keyword(s):

Cell Wall ◽

Root Hair ◽

Root Hairs ◽

Root Apex ◽

Alnus Glutinosa ◽

Root Surface ◽

Infection Process ◽

Root Cap ◽

A Cell ◽

Histochemical Tests

The aim of the present study was to investigate the Alnus root surface using seedlings grown axenically. This study has focused on root zones where infection by the symbiotic actinomycete Frankia takes place. The zones examined extend from the root cap to the emerging root hair zone. The root cap ensheaths the Alnus root apex and extends over the root surface as a layer of highly flattened cells closely appressed to the root epidermal cell wall. These cells contain phenolic compounds as demonstrated by various histochemical tests. They are externally bordered by a thin cell wall coated by a thin mucilage layer. The root cap is ruptured when underlying epidermal cells elongate, and cell remnants are still found in the emerging root hair zone. Young emerging root hairs are bordered externally by a cell wall covered by a thin mucilage layer which reacts positively to the tests used for the detection of polysaccharides, glycoproteins, and anionic sites. The characteristics of the Alnus root surface and the biological function of mucilage and phenols present at the root surface are discussed in relation to the infection process.

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Structure and ontogeny of Betula alleghaniensis – Pisolithus tinctorius ectomycorrhizae

Canadian Journal of Botany ◽

10.1139/b90-077 ◽

1990 ◽

Vol 68 (3) ◽

pp. 579-593 ◽

Cited By ~ 33

Author(s):

H. B. Massicotte ◽

R. L. Peterson ◽

C. A. Ackerley ◽

L. H. Melville

Keyword(s):

Root Hairs ◽

Root Surface ◽

Pisolithus Tinctorius ◽

Initial Contact ◽

Broad Host Range ◽

Betula Alleghaniensis ◽

Cortical Cells ◽

Structural Modifications ◽

Hartig Net ◽

Primary Roots

The ontogeny and ultrastructure of ectomycorrhizae synthesized between Betula alleghaniensis (yellow birch) and Pisolithus tinctorius, a broad host range fungus, were studied to determine the structural modifications in both symbionts during ectomycorrhiza establishment. A number of stages, including initial contact of hyphae with the root surface, early mantle formation, and mature mantle formation, were distinguished. Interactions between hyphae and root hairs were frequent. As a paraepidermal Hartig net developed, root epidermal cells elongated in a radial direction, but wall ingrowths were not formed. Repeated branching of Hartig net hyphae resulted in extensive fine branches and the compartmentalization of hyphal cytoplasm. Nuclei and elongated mitochondria were frequently located in the narrow cytoplasmic compartments, and [Formula: see text] thickenings developed along walls of cortical cells in primary roots.

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Rhythmic patterns of nutrient acquisition by wheat roots

Functional Plant Biology ◽

10.1071/pp01130 ◽

2002 ◽

Vol 29 (5) ◽

pp. 595 ◽

Cited By ~ 21

Author(s):

Sergey Shabala ◽

Andrew Knowles

Keyword(s):

Root Zone ◽

Root Hairs ◽

Rhythmic Activity ◽

Root Apex ◽

Root Surface ◽

Ion Flux ◽

Nutrient Acquisition ◽

Wheat Roots ◽

Non Invasive ◽

Functional Zone

Oscillatory patterns in H+, K+, Ca2+ and Cl- uptake were observed at different regions of the root surface, including root hairs, using a non-invasive ion flux measuring technique (the MIFE™ technique). To our knowledge, this is the first report of ultradian oscillations in nutrient acquisition in the mature root zone. Oscillations of the largest magnitude were usually measured in the elongation region, 2–4 mm from the root apex. There were usually at least two oscillatory components present for each ion measured: fast, with periods of several minutes; and slow, with periods of 50–80 min. Even within the same functional zone, the periods of ion flux oscillations were significantly different, suggesting that they are driven by some internal mechanisms located in each cell rather than originating from one ‘central clock pacemaker’. There were also significant changes in the oscillatory characteristics (both periods and amplitudes) of fluxes from a single small cluster of cells over time. Analysis of phase shifts between oscillations in different ions suggested that rhythmic activity of a plasma membrane H+-pump may be central to observed rhythmic nutrient acquisition by plant roots. We discuss the possible adaptive significance of such an oscillatory strategy for root nutrient acquisition.

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Root hairs bridge the gap between roots and soil water

10.5194/egusphere-egu2020-11660 ◽

2020 ◽

Author(s):

Patrick Duddek ◽

Mutez Ahmed ◽

Mohsen Zarebanadkouki ◽

Nicolai Koebernick ◽

Goran Lovric ◽

...

Keyword(s):

Water Uptake ◽

Contact Area ◽

Geodesic Distance ◽

Root Hairs ◽

Root Water Uptake ◽

Root Surface ◽

Particle Packing ◽

Biophysical Properties ◽

Soil Matrix ◽

Water Potentials

Although 40% of total terrestrial precipitation transits the rhizosphere, there is still substantive lack of understanding of the rhizosphere biophysical properties and their impact on root water uptake. Our hypothesis is that roots are capable of altering the biophysical properties of the rhizosphere and hereby facilitating root water uptake. In particular, we expect that root hairs maintain the hydraulic contact between roots and soil at low water potentials.&#160;We have recently shown that root hairs facilitate root water uptake in dry soils at high transpiration rates. Our explanation was that root hairs extend the effective root radius decreasing the flow velocity at the root surface and hence the drop in matric potential across the rhizosphere.To test this hypothesis, we used synchrotron X-ray CT to image the distribution of root hairs in soils. The experiments were conducted with two maize genotypes (with and without root hairs) grown in two soil textures (loam vs sand). Segmenting the different domains within the high-resolution images enabled us to quantify the contact area of the root surface and root hairs with the soil matrix at different water potentials. Furthermore, we calculated the geodesic distance between the root and the soil matrix as a proxy of the accessibility of water to the root.The results show that root hairs increase the total root surface by approx. 30% and the contact area with the soil matrix by approx. 40%. Furthermore, the average distance from the soil to the root surface decreases by approx. 40% due to hairs, which is the effect of root hairs preferentially growing through macropores. In summary, root hairs not only increase the root surface and the root-soil contact area, but also bridge the air-filled pores between the root epidermis and the soil matrix, thus facilitating the extraction of water. &#160;On top of that, the segmented CT images are also the basis for image-based models aiming at quantifying root water uptake and the effect of root hairs.&#160;&#160;References<ul><li>(1) Koebernick N, Daly KR, Keyes SD, et al. 2019. Imaging microstructure of the barley rhizosphere: particle packing and root hair influences. New Phytologist 221, 1878&#8211;1889.</li> <li>(2) Carminati A, Benard P, Ahmed MA, Zarebanadkouki M. 2017. Liquid bridges at the root-soil interface. Plant and Soil 417, 1&#8211;15.</li> </ul>&#160;

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Colonization of Tomato Root by Pathogenic and Nonpathogenic Fusarium oxysporum Strains Inoculated Together and Separately into the Soil

Applied and Environmental Microbiology ◽

10.1128/aem.72.2.1523-1531.2006 ◽

2006 ◽

Vol 72 (2) ◽

pp. 1523-1531 ◽

Cited By ~ 89

Author(s):

Chantal Olivain ◽

Claude Humbert ◽

Jarmila Nahalkova ◽

Jamshid Fatehi ◽

Floriane L'Haridon ◽

...

Keyword(s):

Fusarium Oxysporum ◽

Laser Scanning ◽

Root Surface ◽

Laser Scanning Microscopy ◽

Pathogenic Strain ◽

Confocal Laser ◽

Fungal Colonization ◽

Tomato Root ◽

Tomato Roots ◽

Nonpathogenic Strain

ABSTRACT In soil, fungal colonization of plant roots has been traditionally studied by indirect methods such as microbial isolation that do not enable direct observation of infection sites or of interactions between fungal pathogens and their antagonists. Confocal laser scanning microscopy was used to visualize the colonization of tomato roots in heat-treated soil and to observe the interactions between a nonpathogenic strain, Fo47, and a pathogenic strain, Fol8, inoculated onto tomato roots in soil. When inoculated separately, both fungi colonized the entire root surface, with the exception of the apical zone. When both strains were introduced together, they both colonized the root surface and were observed at the same locations. When Fo47 was introduced at a higher concentration than Fol8, it colonized much of the root surface, but hyphae of Fol8 could still be observed at the same location on the root. There was no exclusion of the pathogenic strain by the presence of the nonpathogenic strain. These results are not consistent with the hypothesis that specific infection sites exist on the root for Fusarium oxysporum and instead support the hypothesis that competition occurs for nutrients rather than for infection sites.

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Factors affecting adsorption of Azospirillum brasilense Cd to root hairs as compared with root surface of wheat

Canadian Journal of Microbiology ◽

10.1139/m89-155 ◽

1989 ◽

Vol 35 (10) ◽

pp. 936-944 ◽

Cited By ~ 28

Author(s):

Yoav Bashan ◽

Hanna Levanony

Keyword(s):

Azospirillum Brasilense ◽

Root Hairs ◽

Growth Conditions ◽

Root Surface ◽

Logarithmic Phase ◽

Bacterial Cells ◽

Beneficial Bacteria ◽

Factors Affecting ◽

Associative Bacteria ◽

Bacterial Adsorption

Electron microscopy of wheat (Triticum aestivum) roots inoculated with Azospirillum brasilense Cd revealed massive adsorption of bacterial cells to the root surface and less adsorption to root hairs. Quantitative analysis of A. brasilense Cd adsorption to root surface and to root hairs, confirmed qualitatively by light microscopy observations, revealed a bacterial adsorption ratio of 5 (+2): 1 (root surface: root hairs). Extreme bacterial adsorption ratios were recorded when bacteria were previously grown in the presence of KNO3 (27:1) or when bacterial cells were inoculated under hydroponic plant growth conditions (80:1). Adsorption of A. brasilense Cd to roots was directly related to the bacterial growth phase, with logarithmic phase cultures demonstrating a greater adsorption than stationary phase cultures. Adsorption to root hairs was dependent mainly on the number of root hairs developed under certain growth conditions. When very few root hairs had developed, most of the bacterial cells were adsorbed to the root surface. Factors such as starvation, bacteria grown in culture in the presence of KNO3, addition of several nutrients, and protease or NaEDTA treatments of bacterial cells before the adsorption assay decreased bacterial adsorption to root hairs. Other factors such as microaerophilic growth conditions, addition of several bacterial chemoattractants, and cellulase-treated root hairs enhanced bacterial adsorption. It is proposed that although A. brasilense Cd adsorbed to every part of the root system, more cells adsorbed to the root surface of wheat than to the root hairs.Key words: associative bacteria, Azospirillum, bacterial adsorption, beneficial bacteria, rhizosphere bacteria, root-hair colonization.

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Root hair specification and its growth in response to nutrients

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha49212258 ◽

2021 ◽

Vol 49 (2) ◽

pp. 12258

Author(s):

Xian HUANG ◽

Tianzhi GONG ◽

Mei LI ◽

Cenghong HU ◽

Dejian ZHANG ◽

...

Keyword(s):

Root Hair ◽

Reverse Genetics ◽

Current Knowledge ◽

Plant Root ◽

Root Hairs ◽

Root Surface ◽

Root Surface Area ◽

Root Hair Development ◽

Hair Development ◽

Calcium Iron

Plant root hairs are cylindrical tubular projections from root epidermal cells. They increase the root surface area, which is important for the acquisition of water and nutrients, microbe interactions, and plant anchorage. The root hair specification, the effect of root hairs on nutrient acquisition and the mechanisms of nutrients (calcium, iron, magnesium, nitrogen, phosphorus, and potassium) that affect root hair development and growth were reviewed. The gene regulatory network on root hair specification in the plant kingdom was highlighted. More work is needed to clone the genes of additional root hair mutants and elucidate their roles, as well as undertaking reverse genetics and mutant complementation studies to add to the current knowledge of the signaling networks, which are involved in root hair development and growth regulated by nutrients.

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Granular Size Effect of Clinoptilolite on Maize Seedlings Growth

The Open Agriculture Journal ◽

10.2174/1874331501004010023 ◽

2010 ◽

Vol 4 (1) ◽

pp. 23-30 ◽

Cited By ~ 5

Author(s):

Alessandra Trinchera ◽

Carlos Mario Rivera ◽

Simona Rinaldi ◽

Anna Salerno ◽

Elvira Rea ◽

...

Keyword(s):

Organic Fertilizer ◽

Root Hairs ◽

Microscopic Analysis ◽

Root Surface ◽

Limited Data ◽

Root Cells ◽

Enhanced Production ◽

Growing Medium ◽

Isolated Roots ◽

Inert Substrate

Clinoptilolite has been successfully used in growing media for containerized horticultural and floricultural production. However, limited data exist on the effects and interaction between particle size and organic nutrient enrichment of the clinoptilolite. One granular (1-3 mm) and micronized (< 30 µm) clinoptilolite was added to quartz sand, an inert growing substrate, at two doses (0.1% and 3% v/v), without or with addition of wine vinasse as nutrient source at four concentrations (0 mgF×Lsubst-1, 10 mgF×Lsubst-1, 100 mgF×Lsubst-1 and 1000 mgF×Lsubst-1) to evaluate their effect on root growth for five days or the appearance of the second true leaf. Root mucigel was produced in zones where clinoptilolite particles adhered to the root surface. Microscopic analysis of isolated roots showed the increase of secondary roots and the proliferation of root hairs in maize treated with both micronized and granular clinoptilolite, with the contemporary production of root mucigel in zones where zeolite particles adhered to the root surface. It is hypothesized that the enhanced production of mucigel by root cells can favour not only the penetration of roots into the inert substrate, but also the solubilization of organic matter and nutrient availability, in particular when micronized clinoptilolite was present in the growing medium. Therefore, micronized clinoptilolite behaved as a sort of a “physical stimulant” for roots during seedlings, promoting, as a consequence, maize shoot development. Effectively, the highest increase in shoot growth was observed at the highest dose (3% v/v) of micronized zeolite, with the optimal rate of organic fertilizer (100 mgF×Lsubst-1).

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In Silico Studies on Structural Function of Melanin Concentrating Hormone Receptor 1 Through Docking Approach, Towards Designing Drug for Treating Obesity

Rwanda Journal of Engineering Science Technology and Environment ◽

10.4314/rjeste.v3i2.7 ◽

2020 ◽

Vol 3 (2) ◽

Author(s):

Mutangana Dieudonne ◽

Musafili Narcisse ◽

Nyurahayo Jean Gaetan ◽

Munyampundu Jean Pierre

Keyword(s):

Hormone Receptor ◽

In Silico ◽

Energy Homeostasis ◽

3D Structure ◽

Zona Incerta ◽

Structural Function ◽

Potential Candidate ◽

In Silico Studies ◽

Melanin Concentrating Hormone ◽

Predicted Model

Melanin concentrating hormone receptor 1 is a G-protein coupled protein receptor expressed in the lateral hypothalamus and zona incerta, part of the nervous system that regulates feeding behavior and energy homeostasis. It is involved in the stimulation of appetite, this was seen when synthetic MCHR1 or MCH was administered to mice and it resulted in induced obesity due to the enhanced feeding. Many researchers have successfully find out the functions of several proteins, using computational approach. It is in this context that in this study the structural function of melanin concentrating hormone receptor 1 through docking studies has been done to make sure that those who are working to address the problem of obesity while trying to discover the effective drugs gain much insight about this receptor. The in silico methods have been used to predict the model of melanin concentrating hormone receptor 1. The template used for model prediction was human delta opioid receptor with the accession number 4N6H. The predicted model has been evaluated and found to be of good quality. Docking was done to investigate the interaction between the ligand; a bifunctional peptide ‘1-oleoyl-r-glycerol’ and the predicted model of melanin concentrating hormone receptor 1 which showed that fourteen residues interacted between the predicted model and ligand. Among interacting residues, it was realized that some of them are involved in sugar metabolism. Thus this study suggests a potential candidate for drug design against cancer and diabetes. Keywords: obesity, MCHR-1, docking, structural function, 3D structure, phylogenetic analysis, interacting residues

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Phosphorus-induced change in root hair growth is associated with IAA accumulation in walnut

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha49412504 ◽

2021 ◽

Vol 49 (4) ◽

pp. 12504

Author(s):

Yongjie XU ◽

Chunyong XU ◽

Dejian ZHANG ◽

Xianzhen DENG

Keyword(s):

Root Hair ◽

Hair Growth ◽

Juglans Regia ◽

Root Hairs ◽

Forest Tree ◽

Root Surface ◽

Nutrient Contents ◽

Phosphorus Stress ◽

Low Phosphorus ◽

Root Hair Growth

Walnut, an important non-wood product forest tree, has free root hairs in orchards. Root hairs are specialized cells originating from the root epidermis that are regulated by plant hormones, such as auxins. This study was conducted to evaluate the effect and mechanism of phosphorus stress on root hair growth of walnut (Juglans regia L.) seedings by auxin (IAA) biosynthesis and transport. Both low phosphorus (LP) and no phosphorus stresses (NP) heavily decreased plant height, leaf number, total root length, root surface, shoot and root biomass, and root nutrient contents. The LP treatment significantly increased root hair growth, accompanied with up-regulation of the positive regulation root hair growth gene JrCPC and down-regulation of the negative regulation root hair growth gene JrTTG1, while the NP treatment had opposite effects. The root IAA level, IAAO activities, IAA transport genes (JrAUX1, JrLAX1, and JrPIN1), and the biosynthesis genes (JrTAA1 and JrTAR1) were increased by the LP treatment, while the NP treatment decreased all of them. Interestingly, the auxin biosynthesis gene CsYUCCA1 was not affected, which suggested that P mainly affects root hair growth of walnut by regulating auxin transport, and then affects root nutrient absorption and plant growth.

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