Effect of proline on wound vessel member formation

Pretreatment of Coleus blumei (BENTH.) stem explants for 24hr with L-proline (P) (1.0 mM) by the successive cup techniqueresulted in the redifferentiation of extremely high numbersof wound vessel members (WVM) from pith and cortical parenchymatissues following the addition of a xylogenic concentrationof 5 ppm indoleacetic acid (IAA). The addition of P with auxinor after auxin had been introduced into the segments was ineffectivein altering the numbers of WVM formed as compared to controls.P-treated segments showed both normal and aberrant WVM withthe addition of colchicine (0.01 %) and IAA; colchicine-treatedsegments invariably produced aberrant WVM when P and IAA weregiven. These results suggest that a P-rich substance may interactwith auxin in initiating wound vessel member differentiation. ¹Fulbright Professor of Botany, 1967-68. Permanent address:Department of Biological Sciences, University of Idaho, Moscow,Idaho, 83843, U. S. A.     

Role of Cytokinin in Vessel Regeneration in Wounded Coleus Internodes

Cytokinin was found to be a controlling or limiting factor invessel regeneration around a wound in internodes of Coleus blumeiBenth. in which the endogenous cytokinin level was minimized.The cytokinin was applied in aqueous solution to the base ofexcised, mature internodes that had an active vascular cambium.Each internode also received IAA in lanolin at its apical end.Under low (0.1 %, w/w) or high (10%, w/w) auxin concentrations,the control internodes (without exogenous cytokinin) exhibitedsmall amounts of vessel regeneration. At appropriate concentrationszeatin, kinetin and 6-benzylamino-purine (BAP) induced a significantincrease in vessel regeneration around the wound. The threecytokinins also induced novel patterns of supplementary regenerationfurther from the wound surface. Kinetin and BAP showed the strongestpromoting effect at 5 and 10 µg ml^–1, while zeatinwas most effective at 20 µg ml^–1. At a low (0.1%) auxin level zeatin was the most effective cytokinin, whereaskinetin was the most effective one at high (1 %) auxin. An inhibitoryeffect on vessel regeneration was observed at the highest kinetinconcentration tested (50 µg ml^–1). The regenerationof vessels induced by cytokinin was very polar. Many more regeneratedvessel members differentiated below the wound than above it,and the regeneration process proceeded acropetally from thebase of the internode to its upper parts. Our results implya basipetal polar increase in cambium responsiveness along thestem axis from internode 5 to 7. The possible significance ofsuch a basipetal increase in cambium sensitivity in wood formationin trees is discussed. Auxin, Coleus blumei, cytokinin, vascular differentiation, vessel regeneration, wound xylem     

Electron Microscopy and Electrophysiology of Local Cell Wall Formation in Chara corallina

The formation of fibrillar and amorphous local wall appositionsinduced by wounding and treatment with chlortetracycline (CTC)was studied in internodal cells of Chara corallina. Woundingcauses a transient depolarisation of the membrane and a transientincrease in membrane conductance. The formation of a fibrillar,cellulosic wound wall starts after the cell wall lesion hasbeen plugged by vacuolar crystals and cytoplasmic inclusions.At that time both membrane potential and membrane conductancehave recovered their normal values. CTC induces a persistentelectrophysiological response and formation of the amorphous,callose-containing wall appositions takes place at low (morepositive) membrane potential and low membrane resistance, suggestingan increased passive membrane permeability. The electrophysiologicalchanges increase with the Ca²⁺ concentration of the CTC solution.The relevance of the membrane potential for the formation oflocal wall appositions is discussed. (Received June 29, 1993; Accepted September 16, 1993)     

Vessel element formation in cultured carrot-root phloem slices

The effects of light, auxin and cytokinin on vessel elementformation in phloem slices of carrot root were examined. When slices of carrot cultivars, ‘Nakamura-senko-futo’and ‘Yamada-hyakunichisenk6- naga’, preculturedin the dark on modified Murashige and Skoog's medium for twodays were cultured on a medium containing 5x10^–6 M 2,4-Din the dark, no vessel element formation occurred. When preculturedslices were cultured in the light with 5x10^–6M 2,4-D,vessel element formation was remarkable. But when 5x10^–7Mkinetin, benzyladenine or zeatin was added, vessel elementswere readily formed even in the dark. When slices were cultured in the light, a cytokinin-like substance(s)that causes vessel element formation was produced in the slices,then was released to the medium. The substance(s) was fairlystable to heat. In slices of carrot cultivars, kuroda-gosun, ‘Kintoki’and ‘Kokubu-senk6-6naga’, a different result forvessel element formation was obtained. When slices of thesecultivars were cultured on a medium containing 5x10^–6M2,4-D in the dark, vessel element formation was remarkable.It seemed, therefore, that these cultivars contain enough ofa cytokinin-like substance(s) to form vessel elements. In fact,vessel element forming activity was found in the alcohol extractof carrot root phloem from these cultivars. (Received June 8, 1971; )     

A possible role for membrane depolarization in epithelial wound healing

Linear narrow wounds produced on cultured bovine corneal endothelial monolayers heal by actin cable formation at the wound border and lamellar crawling of cells into the injured area. We report the novel finding that membrane potential depolarization occurs at the leading edge of wounds and gradually extends inward toward the neighboring cells. We have determined that the replacement of extracellular Na⁺ by choline and the incorporation of phenamil, an inhibitor of the epithelial Na⁺ channel (ENaC), provoke a decrease in the actin cable and depolarization areas and in the lamellar activity of the wound edges. To the contrary, extracellular Li⁺ can successfully replace Na⁺ in the determination of the depolarization and cytoskeletal responses. This finding supports the idea that membrane depolarization, not the increase in intracellular Na⁺ concentration, is responsible for the formation of the actin cable, a result that is in agreement with previous evidence showing that nonspecific depolarization of the plasma membrane potential (PMP) of epithelial cells may promote characteristic cytoskeletal rearrangements per se (Chifflet S, Hernández JA, Grasso S, and Cirillo A. Exp Cell Res 282: 1–13, 2003). We suggest that spontaneous depolarization of the PMP of the cells at the wound borders determined by a rise in the ENaC activity of these cells constitutes an additional factor in the intermediate cellular processes leading to wound healing in some epithelia. actin; epithelial sodium channel     

Calcium Antagonist TMB-8 Inhibits Cell Wall Formation and Growth in Pea

The effects on auxin-stimulated growth and cell wall formationof 8-(N, N-diethylamino)-octyl-3, 4, 5-trimethoxybenzoate.HCI(TMB-8), an intracellular Ca²⁺ antagonist, were investigatedin abraded stem segments from aetiolated seedlings of Pisumsativum L. cv. Alaska. Incubation of segments at pH 6.0 with200 mmol m^–3 TMB-8 resulted in a 50% inhibition of auxin-stimulatedgrowth. Added Ca²⁺ did not restore normal auxin-stimulated growth,presumably because of its well-known stiffening effect on thecell wall. In segments incubated at a pH (7–2) which preventedelongation, auxin promoted the incorporation of [³H]glucoseinto the cell wall relative to total uptake of label. TMB-8abolished about 60% of the total incorporation of label intocell walls in the presence of auxin, but was not effective inthe absence of auxin. Exogenous CaCl₂ reversed the inhibitoryeffect of TMB-8 on relative cell wall incorporation in a parabolicmanner, with a 50% reversal at about 100 mmol m^–3 andcomplete reversal at 1.0 mol m^–3 Ca²⁺. Other ions tested(Mg²⁺, Mn²⁺, Cu²⁺, Zn²⁺) were without substantial effect atconcentrations of 0.5 mol m^–3. Both apparent uptake ofCa²⁺ and consequent reversal of TMB-8 inhibition of cell wallincorporation were blocked by the Ca²⁺ channel blockers verapamiland La³⁺. The data provide further evidence that auxin-stimulatedgrowth is dependent upon continued cell wall incorporation,and suggest that a Ca²⁺ messenger system may be involved inthe promotory actions of auxin on cell wall synthesis and long-termgrowth. Key words: Auxin, calcium, cell wall synthesis     

Possible Role of Hexosamine-Containing Cell Wall Component in Growth Regulation of Rice Coleoptiles

The cell wall of rice coleoptile was found to contain severalhundred microgram hexosamine per gram dry wt with the pectic,hemicellulosic, and -cellulose fractions containing 50%, 40%,and 10%, respectively. The cell wall hexosamine content increasedseveralfold with coleoptile growth and was higher in air-typecoleoptiles (grown on the surface of water) than water-typeones (grown under water). Rice coleoptiles were cultured in glucosamine, NH₄⁺, glutamine,or asparagine solution and growth was inhibited at 10^–4M and above. Coleoptile growth capacity in glucosamine or NH₄⁺solution correlated inversely with the cell wall hexosaminecontent. Both of these solutions also inhibited elongation ofsubmerged air-type coleoptile sections. Azaserine promoted thegrowth of both intact and excised coleoptiles at 10^–6to 10^–5 M and halved the cell wall hexosamine contentof intact ones. 6-Diazo-5-oxo-L-norleucine promoted the elongationof sections. These results suggest that the hexosamine-containingcell wall component is an important growth suppression factorin rice coleoptiles. (Received April 25, 1983; Accepted August 30, 1983)     

Microscopic and submicroscopic observation of the effects of coumarin and colchicine during elongation of pine seedlings

The effects of coumarin and colchicine were investigated ona microscopic and submicroscopic level. Both chemicals induced a high degree of cell swelling of intactpine seedlings in the concentration of 10^–3 M–7x 10^–3 M coumarin and 6 x 10^–3 M–10^–2M colchicine. In seedlings radially enlarged due to coumarintreatment, primary phloem regions were characterized by cellcrushing. Furthermore, protrusion of many large or small vesicleswere found closely attached to the plasmalemma of parenchymacells. The relationship of the latter evidence with the possibilityof breakdown of the cell wall is discussed. Colchicine induced abnormal spiral thickenings, and the depositionof cell wall materials was somewhat disturbed when seedlingswere treated with this chemical for a longer period (more than10 days). Based on this evidence, it was suggested that colchicinedid not completely destroy the organized pattern of spiral wallthickening. (Received September 16, 1975; )     

Effect of Metabolic Inhibitors on the Formation of Cell Walls in a Green Alga, Micrasterias crux-melitensis

The effects of cytochalasin B, N-ethylmaleimide (NEM), colchicine,vinblastine and cycloheximide on the formation of birefringentcell wall layers were studied. Birefringent layers accumulatedoutside the plasma membrane of daughter semicells when cellswere cultured in a 0.16 M mannitol solution without any inhibitors.In cells treated with 2 x 10^–5 M cytochalasin B, 3 x 10^–5M NEM, 10^–4 M vinblastine or 10^–5 M cycloheximidefor 24 hr, birefringent layers were not observed outside theplasma membrane, but were present in cells treated with 10^–2M colchicine. The possibility is discussed that substances necessaryfor wall synthesis could be transported from the cytoplasm tothe outside of the plasma membrane by a system associated withmicrofilaments, microtubules and myosin-like structures. (Received June 26, 1981; Accepted September 24, 1981)     

一种特殊的长寿细胞: 毛竹茎秆纤维细胞

利用显微和细胞化学方法, 对毛竹( Phyllostachys edulis) 茎秆纤维次生壁形成过程中超微结构变化以及ATP 酶、Ca²⁺ -ATP_ase 和酸性磷酸酶的超微细胞化学定位进行了研究。研究发现, 次生壁形成早期,细胞核具有双层核膜, 染色质凝聚, 可见大量的线粒体、粗面内质网和高尔基体等细胞器存在于纤维细胞中; 随后, 双层核膜消失, 细胞器将逐渐解体, 多泡体开始出现在纤维细胞的细胞质; 随着年龄的增加,纤维细胞壁逐渐增厚, 并出现多层结构现象, 而运输小泡、细胞膜、胞间连丝和凝聚的染色质将持续存在。在次生壁形成的整个过程中, ATP 酶、Ca²⁺ -ATP_ase 和酸性磷酸酶在运输小泡、细胞膜、质膜内陷、胞间连丝和凝聚的染色质中将持续存在。结果表明, 毛竹茎秆纤维细胞是一种不同于木本双子叶植物的长寿细胞, 纤维原生质体中ATP 酶和酸性磷酸酶的持续存在与次生壁的持续增厚密切相关。     

Exogenous Auxin and N-1 -Naphthylphthalamic Acid Effects on Populus deltoides Xylogenesis

A method was developed for evaluating the empirical alterationof xylem vessel differentiation in the central leaf trace ofPopulus deltoides, a species that exhibits helical phyllotaxis.Effects of experimental treatments for a period of six plastochronswere evaluated by vessel parameter ratios = 2.P_T/ (P_T+1 + P_T–1),where P was either vessel number or mean transverse vessel areameasured at mid-intern ode at Leaf Plastochron Indices of T– 1, T, and T + 1. Excising leaf laminae reduced vesselnumber and mean vessel area in the associated central leaf traceby 50% and 70%, respectively, compared to unexcised laminaecontrols. Replacing excised laminae with a concentration seriesof exogenous indoleacetic acid (IAA) resulted in a 5% increaseper log mol m^–3 of IAA in the number of vessels differentiatingin the associated central leaf traces compared to excised controls.Mean vessel areas within these leaf traces were 50% of thoseof intact leaf traces. No significant effects of different concentrationsof exogenously applied IAA on mean vessel area could be demonstrated.A lanolin paste ring of N-1 -naphthylphthalamic acid (NPA),an auxin transport inhibitor, around the petioles of intactleaves reduced the number of differentiating vessels by 7% andmean vessel area by 29% per log mol m^–3 of NPA comparedto central leaf traces of leaves ringed with plain lanolin paste.The results suggest that NPA treatments may be used to distinguishexperimentally, at least in part, the cell division from thecell enlargement phases of primary xylogenesis within centralleaf traces of P. deltoides stems. Key words: Auxin transport, Vessel area, Vessel number     

Relationships between Adsorption, Chemical State and Fluxes of Cadmium Applied as Cd(NO3)2 in Isolated Xylem Cell Walls of Tomato

Wolterbeek, H. Th. 1987. Relationships between adsorption, chemicalstate and fluxes of cadmium applied as Cd(NO₃)₂ in isolatedxylem cell walls of tomato.—J. exp. Bot. 38: 419–432. Isolated xylem cell wall pieces were applied as membranes inion diffusion experiments. The cell walls were isolated fromtomato internodes (Lycopersicon esculentum Mill, cv. Tiny Tim)and sealed in a two-compartment diffusion system. In flux andadsorption calculations, the cell wall was regarded as a leakymembrane with parallel fluxes through Donnan Free Space (DFS)and Water Free Space (WFS). During the experiments absorptioninto and diffusion across the walls was determined of Cd^{2 +}, applied as ¹¹⁵Cd(NO₃)₂. Flux experiments with ⁸²Br^–indicated that excluded volume effects and path tortuosity resultedin apparent WFS diffusion coefficients in the walls which were0·012 times as high as in water. The free proton concentration in the DFS was shown to be relatedto a complex formation between fixed charges and Cd^{2 +}. Thecell wall permeability for Cd^{2 +} and NO₃^– varied withapplied and absorbed concentrations, and the Cd^{2 +} flux curveshowed an inflexion point coinciding with a buffered degreeof dissociation of fixed charges in the DFS. The necessary couplingof fluxes of opposite charges resulted in relatively high NO₃^–and small Cd^{2 +} permeability of the DFS for strongly dilutedsolutions (P = 10^–4 m s^–1 and 10^–11 m s^–1for NO₃^– and Cd^{2 +} respectively). The results demonstratethe possible regulatory effects of the cell wall in processesof ion transfer from xylem vessels, or ion uptake in plant tissues. Key words: Cadmium, chemical state, DFS, WFS, ion flux, permeability, xylem cell walls, tomato, bromium, nitrate     

Accumulation of Heavy Metals in Cell Walls of Polygonum cuspidatum Roots from Metalliferous Habitats

The distribution and accumulation of Cu²⁺, Zn²⁺ and Cd²⁺ ionsin the roots of Polygonum cuspidatum, collected from metalliferousand non-metalliferous habitats, were examined. About 90% ofthe metal ions was located in the cell wall fraction of rootsof plants grown in either type of habitat. The metal-ion exchangecapacity of the cell walls is not specific to the plants frommetalliferous habitats, and there were no significant differencesamong plants from the various habitats. The capacity for Cu²⁺ions was greater than that for Zn²⁺ or Cd²⁺ ions. Cu²⁺ ionshave a high affinity for the cell wall and, thus, it appearsthat the cell wall is a barrier for the transportation of Cu²⁺into the cytoplasm. (Received March 10, 1988; Accepted March 17, 1989)     

The Role of Basipetal Auxin Transport in the Positional Control of Abscission Sites Induced in Impatiens sultani Stem Explants

If segments of Impatiens sultani stem are explanted and incubated,separation layers often form across them and lead to abscission.To test the suggested role of auxin concentration in controllingthe position of abscission sites, explants were labelled byapplying [¹⁴C]IAA to the shoot tip 4 h prior to explanting;transport of auxin applied in this way seems to resemble thatof endogenous auxin. During subsequent incubation of explantsfor 20 h, basipetal transport resulted in ¹⁴C accumulating justabove the base of the explants (nearly 80 % in the bottom 4mm of 24 mm explants). In internodal explants that had beenwounded at explanting by incising one side so as to sever avascular bundle, and in nodal explants with the leaf removed,the ¹⁴C also accumulated just above the wound or node to abouttwice the concentration otherwise expected; this accumulationwas probably due to basipetal transport being impeded by vasculardiscontinuity at the wound or node. Accumulation just abovethe base, or above a wound or node, resulted in gradients of¹⁴C concentration (presumably reflecting endogenous auxin concentration)decreasing in the morphologically upward direction at each ofthese three positions where abscission sites tend to occur. Impatiens sultani, abscission, auxin, IAA, node, polarized transport, positional control, separation layer, wounding     

The Effect of pH on the Binding of Calcium to Pea Epicotyl Cell Walls and its Implications for the Control of Cell Extension

Cell walls were prepared from the epicotyls of dark-grown pea(Pisum sativum L.) seedlings. The walls were found to bind externally-added⁴⁵Ca²⁺, with a binding constant of 4 ? 10^–4 mol dm^–3and a maximum capacity of 1.5 ? 10^–8 g-ions of Ca²⁺ perg fresh weight of epicotyl. The binding capacity decreased asthe pH of the medium was decreased below 6.0, suggesting thatthe calcium was bound by an anionic group with an apparent pKof 4.7. More than half the calcium binding was due to polygalacturonicacid in the wall, since up to 60% of the calcium binding capacitywas removed by pre-incubation of the cell walls with polygalacturonase(E.C.3.2.1.15). Only small decreases in calcium binding wereseen following pre-incubation with protease, nucleases, phospholipaseand hemicellulase. These results indicate that calcium willbe displaced from the cell wall at hydrogen ion concentrationswhich are known to occur in the wall during wall extension.They are consistent with a mechanism by which calcium inhibitswall extension by forming ionic bridges between polygalacturonicacid molecules, and also with the hypothesis that calcium andhydrogen ions exert opposing influences on cell wall extensionby competing for the same binding sites on the polygalacturonicacid. Key words: Pea epicotyl, Cell wall, Calcium, pH     

Relations Between Indoleacetic Acid, Calcium Ions and Ethylene in the Regulation of Growth and Cell Wall Composition in Picea abies

Effects of indoleacetic acid, calcium ions and ethylene on thegrowth of and deposition of different cell wall fractions inthe hypocotyl of Norway spruce (Picea abies (L.) Karst.) seedlingswere investigated. Indoleacetic acid progressively stimulated cellulose depositionas the amount of added Ca²⁺ increased. In contrast, indoleaceticacid promoted lignification and the deposition of non-cellulosicpolysaccharides only in the absence of added Ca²⁺ . When Ca²⁺was added, the indoleacetic acid effect disappeared. Similarly,indoleacetic acid promoted non-cellulosic polysaccharide depositiononly in the absence of ethylene. At increasing ethylene levelsthe effect of indoleacetic acid on non-cellulosic polysaccharidedeposition disappeared and indoleacetic acid instead promotedcellulose deposition. The response to indoleacetic acid depended on the Ca²⁺ concentrationand on the rate of ethylene production. The relationship betweenindoleacetic acid and Ca²⁺ seemed complex, but clearly indoleaceticacid could partially overcome a Ca²⁺ deficiency. The resultssuggest that ethylene may be a factor of particular importancefor the type of polysaccharide deposition during cell wall formation. Key words: Calcium, cell wall, conifers, ethylene, indoleacetic acid     

Water content, hydraulic conductivity, and ice formation in winter stems of Pinus contorta: a TDR case study

Stem water content, ice fraction, and losses in xylem conductivity were monitored from November 1996 to October 1997 in an even-aged stand of Pinus contorta (lodgepole pine) near Potlatch, Idaho, USA. A time domain reflectometry (TDR) probe was used to continuously monitor stem water contents and ice fractions. Stem sapwood water contents measured with TDR were not different from water contents measured gravimetrically. The liquid water content of stems ranged from 0.70 m³ m^-3 to 0.20 m³ m^-3 associated with freezing and thawing of the wood tissue. Ice fraction of the stem varied from 0-75% during the winter suggesting liquid water was always present even at ambient temperatures below -20°C. Shoot xylem tensions decreased through the winter to a minimum of ca. -1.4 MPa in February then increased to -0.4 MPa in May. Shoot xylem tensions decreased during the growing season reaching -1.7 MPa by September. Annually, low shoot water potentials were not correlated to decreases in stem hydraulic conductivity. Xylem conductivity decreased due to cavitation through the winter and was 70% of summer values by March. Decreases in xylem conductivity were correlated to low shoot water potentials and cumulative freezing and thawing events within the xylem. Xylem conductivity increased to pre-winter values by May and no reductions in xylem conductivity were observed during the growing season.     

Pollen morphology and structure of Zingiber (Zingiberaceae)

The aim of the present study is to describe the morphology and internal wall structure of Zingiber pollen. The pollen of 18 species of Zingiber was examined by light, scanning and transmission electron microscopy. In the sections Zingiber and Dymczewiczia (Horan.) Benth. the pollen grains are spherical with cerebroid sculpturing while in the section Cryptanthium Horan. the pollen is ellipsoid with spira-striate sculpturing. All species have a thin coherent exine and an intine consisting of a thick, radially channeled outer layer and a thin, finely granular inner layer. On the basis of pollen morphology it is proposed that the section Dymczeniczia is included in the section Zingiber. The structure of the pollen wall in Zingiber resembles that of Canna and Strelitzia in having a pollen wall offering an infinite number of germination sites.     

The time course of xylem differentiation and its relation to deoxyribonucleic Acid synthesis in cultured coleus stem segments

The relationship between DNA synthesis and wound xylem differentiation was investigated in cultured stem segments of Coleus blumei. The addition of 50 micrograms of indoleacetic acid per liter to the culture medium resulted in a 400 to 500% increase in the number of wound vessel members formed in 7 days. However, the time course of wound vessel member formation was similar in segments cultured in the presence and absence of auxin. In either case, no wound vessel members appeared before the 3rd day of culture, while the majority of wound vessel members appeared on the 4th and 5th days of culture. ³H-Thymidine incorporation into DNA was used to measure changes in the DNA synthetic activity of the tissues during the culture period. Comparatively little ³H-thymidine incorporation occurred during the 1st day of culture. Maximum ³H-thymidine incorporation was observed on the 2nd day of culture, 2 days before the peak period of xylem differentiation. The rate of incorporation of ³H-thymidine into DNA decreased with increasing time in culture after the 2nd day. Auxin at 50 micrograms per liter had no effect on the time course of ³H-thymidine incorporation, although somewhat more ³H-thymidine was incorporated into DNA throughout the culture period in the presence of auxin. The magnitude of this effect was small when compared to the effect of auxin on xylem differentiation. The antimetabolite 5-fluorodeoxyuridine was shown to block DNA synthesis in the cultured stem segments. When the tissues were isolated on media containing 10⁻⁶m 5-fluorodeoxyuridine, wound vessel member differentiation was inhibited by approximately 80%, in both the presence and absence of auxin. Thymidine at 10⁻⁵m completely overcame the 5-fluorodeoxyuridine inhibition of wound vessel member formation. 5-Fluorodeoxyuridine was effective in blocking xylogenesis only when this substance was supplied to the tissues during the early part of the culture period. 5-Fluorodeoxyuridine had no effect on xylem differentiation when it was applied after the 3rd day of culture.     

On the Function of Wall Sculpturing in Xylem Conduits

The water-conducting network of capillaries in vascular plants has evolved over hundreds of millions of years in order to beable to cope with bubble clogging,a problem which also affects modern microfluidic devices.Decades of anatomical studieshave revealed that plants growing in habitats in which the formation of bubbles,or emboli,is likely to be a frequent occurrenceoften have various forms of geometrical sculpturing on the internal surfaces of the xylem conduits.The possible function of suchwall sculpturing has long been the subject of speculation.We have investigated the hypothesis that wall sculpturing is a functionaladaptation designed to increase the wettability of the walls of xylem conduits,an effect which could be described as theinverse of the well-known lotus-effect.Our results show that wall sculpturing does enhance wettability.Importantly,theoreticalcalculations reveal that the geometric parameters of various types of wall sculpturing are such that the resulting surfaces aresufficiently rough to enhance wettability,but not significantly rougher.The results provide an appealing answer to thelong-standing debate on the function of wall sculpturing in xylem conduits,and may provide biomimetic clues for new approachesto the removal of bubbles in microfluidic channels.