Investigation of the wetting behaviour of natural lignin - a contribution to the cohesion theory of water transport in plants

Laschimke, Ralf

doi:10.1016/0040-6031(89)85335-3

Cited by 39 publications

(39 citation statements)

References 4 publications

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“…These areas between pit borders are most likely lignins. As in another study (Laschimke, 1989) and in ours, pit aperture rims and pit borders provided some of the strongest staining signals, providing evidence for both hydrophilic properties, staining with Ruthenium Red and the periodic acid Schiff reaction and staining pink with Toluidine Blue, and hydrophobic properties, staining strongly with Schiff reagent, which normally indicates the presence of aldehyde groups but also can be due to residual basic fuchsin in the Schiff reagent binding to phospholipids (Byrne, 1962;Adams and Bayliss, 1971). For any structures to stain with both hydrophilic and hydrophobic dyes clearly indicates an amphiphilic nature.…”

Section: Hydrophobic Surfaces In Xylem Conduitssupporting

confidence: 55%

“…thickenings, warts, crevices, etc. ; Laschimke, 1989;Kohonen, 2006;McCully et al, 2014), which could act as bubble nucleation sites; and (2) surface tension-lowering surfactants have been found in xylem sap (Christensen-Dalsgaard et al, 2011). In this study, we addressed these two apparent contradictions to the cohesion-tension theory by testing them for five plant species from five major angiosperm clades.…”

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confidence: 99%

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Xylem Surfactants Introduce a New Element to the Cohesion-Tension Theory

et al. 2016

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Vascular plants transport water under negative pressure without constantly creating gas bubbles that would disable their hydraulic systems. Attempts to replicate this feat in artificial systems almost invariably result in bubble formation, except under highly controlled conditions with pure water and only hydrophilic surfaces present. In theory, conditions in the xylem should favor bubble nucleation even more: there are millions of conduits with at least some hydrophobic surfaces, and xylem sap is saturated or sometimes supersaturated with atmospheric gas and may contain surface-active molecules that can lower surface tension. So how do plants transport water under negative pressure? Here, we show that angiosperm xylem contains abundant hydrophobic surfaces as well as insoluble lipid surfactants, including phospholipids, and proteins, a composition similar to pulmonary surfactants. Lipid surfactants were found in xylem sap and as nanoparticles under transmission electron microscopy in pores of intervessel pit membranes and deposited on vessel wall surfaces. Nanoparticles observed in xylem sap via nanoparticle-tracking analysis included surfactant-coated nanobubbles when examined by freeze-fracture electron microscopy. Based on their fracture behavior, this technique is able to distinguish between dense-core particles, liquid-filled, bilayer-coated vesicles/liposomes, and gas-filled bubbles. Xylem surfactants showed strong surface activity that reduces surface tension to low values when concentrated as they are in pit membrane pores. We hypothesize that xylem surfactants support water transport under negative pressure as explained by the cohesion-tension theory by coating hydrophobic surfaces and nanobubbles, thereby keeping the latter below the critical size at which bubbles would expand to form embolisms.

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Section: Hydrophobic Surfaces In Xylem Conduitssupporting

confidence: 55%

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confidence: 99%

Xylem Surfactants Introduce a New Element to the Cohesion-Tension Theory

et al. 2016

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“…It is interesting to note that hydrophobic properties of the inner xylem walls seem to be a general feature because similar findings were described for other plants for the xylem and adjacent apoplastic spaces (Lewis, 1945(Lewis, , 1949Scott, 1966 ;Woolley, 1983 ;Jeffree et al, 1987 ;Laschimke, 1989 ;Laschimke & Laschimke, 1998). In these cases, adhesive forces are more likely to limit xylem tensions than cohesive forces and, therefore, assessment of the maximum tensions attainable should consider adhesive as well as cohesive forces.…”

Section: mentioning

confidence: 74%

“…It is well known (Laschimke, 1989 ;Yount, 1989 ;Smith, 1994) that hydrophobic oil droplets are favoured nucleation sites for gas bubble formation of water under tension.…”

Section: mentioning

confidence: 99%

Diurnal changes in xylem pressure of the hydrated resurrection plant Myrothamnus flabellifolia: evidence for lipid bodies in conducting xylem vessels

et al. 1999

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The resurrection plant Myrothamnus flabellifolia has the ability to recover from repeated prolonged and extreme desiccation cycles. During the dry state the inner walls of the xylem vessels seemed to be covered, at least partly, by a lipid film as shown by Sudan III and Nile Red staining. The lipid film apparently functioned as an ' internal cuticle ' which prevented the adjacent parenchyma ray cells from complete water loss. The hydrophobic nature of the inner xylem walls was supported by the finding that benzene ascended as rapidly as water in the xylem of dry Myrothamnus branches. On watering, numerous lipid bodies were found in the water-conducting vessels, presumably formed from the lipid film and\or from lipids excreted from the adjacent living cells into the vessels. The presence of lipid bodies within the vessels, as well as the hydrophobic properties of the inner xylem walls, could explain the finding that the xylem pressure of hydrated, well watered plants (measured both under laboratory and field conditions with the xylem pressure probe) never dropped below c. k0.3 MPa and that cavitation occurred frequently at low negative xylem pressure values (k0.05 to k0.15 MPa). The xylem pressure of M. flabellifolia responded rapidly and strongly to changes in relative humidity and temperature, but less obviously to changes in irradiance (which varied between 10 and c. 4000 µmol m −# s −" ). The morphological position of the stomata in the leaves could explain the extremely weak and slow response of the xylem pressure of this resurrection plant to illumination changes. Stomata were most abundant in the furrows, and were thus protected from direct sunlight. Simultaneous measurements of the cell turgor pressure in the leaf epidermal cells (made by using the cell turgor pressure probe) revealed that the xylem and the cell turgor pressure dropped in a ratio of 1 : 0.7 on changes in the environmental parameters, indicating a quite close hydraulic connection and, thus, water equilibrium between the xylem and cellular compartments. An increase in irradiance of c. 700 µmol m −# s −" resulted in a turgor pressure decrease from 0.63 to 0.48 MPa. Correspondingly, the cell osmotic pressure increased from 1.03 to 1.22 MPa. From these values and by assuming water equilibrium, the osmotic pressure of the xylem sap was estimated to be 0.25-0.4 MPa. This value seems to be fairly high but may, however, be explained by the reduction of the water volume within the vessels due to the floating lipid bodies.

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“…Such results indicate that lignin, at this level of structural organization, prefers the spherical shape if it is not perturbed by interactions with its surroundings. This fact can be explained in terms of lignin's strong hydrophobic property (Laschimke 1989). Of all possible shapes for solid objects, the sphere has the smallest surface area and hence the spherical globule will have the lowest free energy in contact with water, forcing self-assembling supermodules into the spherical structure.…”

Section: Resultsmentioning

confidence: 99%

Visualization of artificial lignin supramolecular structures

et al. 2000

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Summary:In this paper we are presenting the results of our environmental scanning electron microscopy (ESEM) investigation of the lignin model compound-enzymatically polymerized coniferyl alcohol, also known as dehydrogenate polymer (DHP). The goals of this study were to visualize the supramolecular organization of DHP polymer on various substrates, namely graphite, mica, and glass, and to explore the influence of substrate surface properties and associated collective phenomena on the lignin self-assembled supramolecular structure. Based on results obtained with ESEM, combined with previously published results based on scanning tunneling microscopy (STM) and electron spin resonance (ESR) technique, we looked at lignin structure ranging from a monomer on a fraction of nanometer scale to a large aggregate on a fraction of millimeter scale, therefore using six orders of magnitude range of size. Herein, we are presenting evidence that there are at least four different levels of the supramolecular structure of lignin, and that its supramolecular organization is well dependent on the substrate surface characteristics, such as hydrophobicity, delocalized orbitals, and surface-free energy.

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Investigation of the wetting behaviour of natural lignin - a contribution to the cohesion theory of water transport in plants

Cited by 39 publications

References 4 publications

Xylem Surfactants Introduce a New Element to the Cohesion-Tension Theory

Xylem Surfactants Introduce a New Element to the Cohesion-Tension Theory

Diurnal changes in xylem pressure of the hydrated resurrection plant Myrothamnus flabellifolia: evidence for lipid bodies in conducting xylem vessels

Visualization of artificial lignin supramolecular structures

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