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Diehl D, Knott M, Schaumann GE. Purification effects show seed and root mucilage's ability to respond to changing rhizosphere conditions. Biopolymers 2023; 114:e23561. [PMID: 37435955 DOI: 10.1002/bip.23561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 06/11/2023] [Accepted: 06/26/2023] [Indexed: 07/13/2023]
Abstract
Mucilage, a polysaccharide-containing hydrogel, is hypothesized to play a key role in the rhizosphere as a self-organized system because it may vary its supramolecular structure with changes in the surrounding solution. However, there is currently limited research on how these changes are reflected in the physical properties of real mucilage. This study examines the role of solutes in maize root, wheat root, chia seed, and flax seed mucilage in relation to their physical properties. Two purification methods, dialysis and ethanol precipitation, were applied to determine the purification yield, cation content, pH, electrical conductivity, surface tension, viscosity, transverse 1 H relaxation time, and contact angle after drying of mucilage before and after purification. The two seed mucilage types contain more polar polymers that are connected to larger assemblies via multivalent cation crosslinks, resulting in a denser network. This is reflected in higher viscosity and water retention ability compared to root mucilage. Seed mucilage also contains fewer surfactants, making them better wettable after drying compared to the two root mucilage types. The root mucilage types, on the other hand, contain smaller polymers or polymer assemblies and become less wettable after drying. However, wettability not only depends on the amount of surfactants but also on their mobility, as well as the strength and mesh size of the network structure. The changes in physical properties and cation composition observed after ethanol precipitation and dialysis suggest that the polymer network of seed mucilage is more stable and specialized in protecting the seeds from unfavorable environmental conditions. In contrast, root mucilage is characterized by fewer cationic interactions and its network relies more on hydrophobic interactions. This allows root mucilage to be more flexible in responding to changing environmental conditions, facilitating nutrient and water exchange between root surfaces and the rhizosphere soil.
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Affiliation(s)
- Doerte Diehl
- Environmental and Soil Chemistry Group, Rheinland-Pfälzische Technische Universität Kaiserslautern Landau, RPTU in Landau, iES Institute for Environmental Sciences, Landau, Germany
| | - Mathilde Knott
- Environmental and Soil Chemistry Group, Rheinland-Pfälzische Technische Universität Kaiserslautern Landau, RPTU in Landau, iES Institute for Environmental Sciences, Landau, Germany
| | - Gabriele E Schaumann
- Environmental and Soil Chemistry Group, Rheinland-Pfälzische Technische Universität Kaiserslautern Landau, RPTU in Landau, iES Institute for Environmental Sciences, Landau, Germany
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Berauer BJ, Akale A, Schweiger AH, Knott M, Diehl D, Wolf M, Sawers RJH, Ahmed MA. Differences in mucilage properties and stomatal sensitivity of locally adapted Zea mays in relation with precipitation seasonality and vapour pressure deficit regime of their native environment. PLANT DIRECT 2023; 7:e519. [PMID: 37600238 PMCID: PMC10435965 DOI: 10.1002/pld3.519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 07/05/2023] [Accepted: 07/27/2023] [Indexed: 08/22/2023]
Abstract
With ongoing climate change and the increase in extreme weather events, especially droughts, the challenge of maintaining food security is becoming ever greater. Locally adapted landraces of crops represent a valuable source of adaptation to stressful environments. In the light of future droughts-both by altered soil water supply and increasing atmospheric water demand (vapor pressure deficit [VPD])-plants need to improve their water efficiency. To do so, plants can enhance their access to soil water by improving rhizosphere hydraulic conductivity via the exudation of mucilage. Furthermore, plants can reduce transpirational water loss via stomatal regulation. Although the role of mucilage and stomata regulation on plant water management have been extensively studied, little is known about a possible coordination between root mucilage properties and stomatal sensitivity as well as abiotic drivers shaping the development of drought resistant trait suits within landraces. Mucilage properties and stomatal sensitivity of eight Mexican landraces of Zea mays in contrast with one inbred line were first quantified under controlled conditions and second related to water demand and supply at their respective site of origin. Mucilage physical properties-namely, viscosity, contact angle, and surface tension-differed between the investigated maize varieties. We found strong influences of precipitation seasonality, thus plant water availability, on mucilage production (R 2 = .88, p < .01) and mucilage viscosity (R 2 = .93, p < .01). Further, stomatal sensitivity to increased atmospheric water demand was related to mucilage viscosity and contact angle, both of which are crucial in determining mucilage's water repellent, thus maladaptive, behavior upon soil drying. The identification of landraces with pre-adapted suitable trait sets with regard to drought resistance is of utmost importance, for example, trait combinations such as exhibited in one of the here investigated landraces. Our results suggest a strong environmental selective force of seasonality in plant water availability on mucilage properties as well as regulatory stomatal effects to avoid mucilage's maladaptive potential upon drying and likely delay critical levels of hydraulic dysfunction. By this, landraces from highly seasonal climates may exhibit beneficial mucilage and stomatal traits to prolong plant functioning under edaphic drought. These findings may help breeders to efficiently screen for local landraces with pre-adaptations to drought to ultimately increase crop yield resistance under future climatic variability.
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Affiliation(s)
- Bernd J. Berauer
- Institute of Landscape and Plant Ecology, Department of Plant EcologyUniversity of HohenheimStuttgartGermany
| | - Asegidew Akale
- Root‐Soil Interaction, TUM School of Life SciencesTechnical University of MunichFreisingGermany
| | - Andreas H. Schweiger
- Institute of Landscape and Plant Ecology, Department of Plant EcologyUniversity of HohenheimStuttgartGermany
| | - Mathilde Knott
- Institute for Environmental Sciences, Group of Environmental and Soil ChemistryRPTU in LandauLandauGermany
| | - Dörte Diehl
- Institute for Environmental Sciences, Group of Environmental and Soil ChemistryRPTU in LandauLandauGermany
| | - Marc‐Philip Wolf
- Institute for Environmental Sciences, Group of Environmental and Soil ChemistryRPTU in LandauLandauGermany
| | - Ruairidh J. H. Sawers
- Department of Plant ScienceThe Pennsylvania State UniversityState CollegePennsylvaniaUSA
| | - Mutez A. Ahmed
- Root‐Soil Interaction, TUM School of Life SciencesTechnical University of MunichFreisingGermany
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How Heterogeneous Pore Scale Distributions of Wettability Affect Infiltration into Porous Media. WATER 2022. [DOI: 10.3390/w14071110] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Wettability is an important parameter that significantly determines hydrology in porous media, and it especially controls the flow of water across the rhizosphere—the soil-plant interface. However, the influence of spatially heterogeneous distributions on the soil particles surfaces is scarcely known. Therefore, this study investigates the influence of spatially heterogeneous wettability distributions on infiltration into porous media. For this purpose, we utilize a two-phase flow model based on Lattice-Boltzmann to numerically simulate the infiltration in porous media with a simplified geometry and for various selected heterogeneous wettability coatings. Additionally, we simulated the rewetting of the dry rhizosphere of a sandy soil where dry hydrophobic mucilage depositions on the particle surface are represented via a locally increased contact angle. In particular, we can show that hydraulic dynamics and water repellency are determined by the specific location of wettability patterns within the pore space. When present at certain locations, tiny hydrophobic depositions can cause water repellency in an otherwise well-wettable soil. In this case, averaged, effective contact angle parameterizations such as the Cassie equation are unsuitable. At critical conditions, when the rhizosphere limits root water uptake, consideration of the specific microscale locations of exudate depositions may improve models of root water uptake.
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4
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Savulescu GC, Rücker M, Scanziani A, Pini R, Georgiadis A, Luckham PF. Atomic force microscopy for the characterisation of pinning effects of seawater micro-droplets in n-decane on a calcite surface. J Colloid Interface Sci 2021; 592:397-404. [PMID: 33689984 DOI: 10.1016/j.jcis.2021.02.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/28/2021] [Accepted: 02/15/2021] [Indexed: 10/22/2022]
Abstract
HYPOTHESIS Roughness is an important parameter in applications where wetting needs to be characterized. Micro-computed tomography is commonly used to characterize wetting in porous media but the main limitation of this approach is the incapacity to identify nanoscale roughness. Atomic force microscopy, AFM, however, has been used to characterize the topography of surfaces down to the molecular scale. Here we investigate the potential of using AFM to characterize wetting behavior at the nanoscale. EXPERIMENTS Droplets of water on cleaved calcite under decane were imaged using quantitative imaging QI atomic force microscopy where a force-distance curve is obtained at every pixel. FINDINGS When the AFM tip passed through the water droplet surface, an attraction was observed due to capillary effects, such that the thickness of the water film was estimated and hence the profile of the droplet obtained. This enables parameters such as the contact angle and contact angle distribution to be obtained at a nanometer scale. The contact angles around the 3-phase contact line are found to be quasi-symmetrically distributed between 10-30°. A correlation between the height profile of the surface and contact angle distribution demonstrates a quasi-proportional relationship between roughness on the calcite surface and contact angle.
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Affiliation(s)
- G C Savulescu
- Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - M Rücker
- Chemical Engineering, Imperial College London, SW7 2AZ, UK; Mechanical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
| | - A Scanziani
- Earth Science and Engineering, Imperial College London, SW7 2AZ, UK
| | - R Pini
- Chemical Engineering, Imperial College London, SW7 2AZ, UK
| | - A Georgiadis
- Chemical Engineering, Imperial College London, SW7 2AZ, UK; Shell Global Solutions International B.V., 2288 GS Rijswijk, The Netherlands
| | - P F Luckham
- Chemical Engineering, Imperial College London, SW7 2AZ, UK
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Kessenich B, Pokhrel N, Kibue JK, Flury M, Maibaum L, De Yoreo JJ. Negatively Charged Lipids Exhibit Negligible Effects on the Water Repellency of Montmorillonite Films. ACS OMEGA 2020; 5:12154-12161. [PMID: 32548396 PMCID: PMC7271367 DOI: 10.1021/acsomega.0c00499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 05/04/2020] [Indexed: 05/04/2023]
Abstract
Amphiphilic molecules can alter the wettability of soil minerals. To determine how the headgroup chemistry of amphiphiles determines these effects, we investigate a system of the clay montmorillonite with long-chain phospholipids. We use phosphatidylglycerol (PG) phospholipids to contrast with our previous work using phosphatidylethanolamine (PE) lipids. Zwitterionic PE lipids can sorb to the negatively charged montmorillonite surface, whereas negatively charged PG lipids cannot. Employing a suite of techniques from molecular dynamics, atomic force microscopy, fluorescence microscopy, and contact angle measurements, we define sample characteristics from molecular-scale structure to the macroscopic wettability. We find that PG lipids do not significantly alter montmorillonite wetting characteristics, such as the contact angle, flow viscosity, and the characteristic time scale for droplet imbibition. On comparing PE and PG lipid/clay films, we find that, among the phospholipids compared, they must have three characteristics to change clay/lipid film wettability: they must bind to the mineral surface, be solid at room temperature, and have a relatively continuous distribution throughout the film.
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Affiliation(s)
- Brenda
L. Kessenich
- Department
of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Nihit Pokhrel
- Department
of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Joshua K. Kibue
- Department
of Materials Science and Engineering, University
of Washington, Seattle, Washington 98195-1700, United States
| | - Markus Flury
- Department
of Crop and Soil Sciences, Washington State
University, Pullman, Washington 99164-6420, United States
| | - Lutz Maibaum
- Department
of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - James J. De Yoreo
- Department
of Materials Science and Engineering, University
of Washington, Seattle, Washington 98195-1700, United States
- Physical
Sciences Division,Pacific Northwest National
Laboratory, Richland, Washington 99354, United States
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Kessenich BL, Pokhrel N, Nakouzi E, Newcomb CJ, Flury M, Maibaum L, De Yoreo JJ. Connecting wettability, topography, and chemistry in a simple lipid-montmorillonite system. J Colloid Interface Sci 2019; 555:498-508. [DOI: 10.1016/j.jcis.2019.07.075] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 10/26/2022]
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Zhou Y, Gao X. Characterization of Biofilm Formed by Phenanthrene-Degrading Bacteria on Rice Root Surfaces for Reduction of PAH Contamination in Rice. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:E2002. [PMID: 31195653 PMCID: PMC6603869 DOI: 10.3390/ijerph16112002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/28/2019] [Accepted: 05/31/2019] [Indexed: 01/13/2023]
Abstract
One effective method in to reduce the uptake of organic contaminants by plants is the development of a root barrier. In this study, the characterization of biofilm structure and function by phenanthrene-degrading Pseudomonas sp. JM2-gfp on rice root surfaces were carried out. Our results showed that root surfaces from three rice species, namely Liaojing401, Koshihikari, and Zhenzhuhong all present hydrophobicity and a high initial adhesion of strain JM2-gfp. Matured robust biofilm formation occurred at 48 h on the root surfaces. The biofilm exhibited cell dense aggregates and biomass embedded in the extracellular polymeric substance (EPS) matrix. EPS composition results showed that the proteins, carbohydrates, lipids and nucleic acids are produced in the biofilm, while the content varied with rice species. Under the initial concentration of phenanthrene 50 mg·L-1, the residual phenanthrene in plant roots from 'Zhengzhuhong', 'Koshihikari' and 'Liaojing401' with biofilm mediated were significantly decreased by 71.9%, 69.3% and 58.7%, respectively, compared to those without biofilm groups after 10 days of exposure. Thus, the biofilm colonized on roots plays an important role of degradation in order to reduce the level of phenanthrene uptake of plants. Thereby, the present work provides significant new insights into lowering the environmental risks of polycyclic aromatic hydrocarbons (PAHs) in crop products from contaminated agriculture soils.
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Affiliation(s)
- Yuman Zhou
- Liaoning Key Laboratory of Molecular Recognition and Imaging, School of Bioengineering, Dalian University of Technology, Dalian 116023, China.
| | - Xiaorong Gao
- Liaoning Key Laboratory of Molecular Recognition and Imaging, School of Bioengineering, Dalian University of Technology, Dalian 116023, China.
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