The microrelief of plant surfaces, mainly caused by epicuticular wax crystalloids, serves different purposes and often causes effective water repellency. Furthermore, the adhesion of contaminating particles is reduced. Based on experimental data carried out on microscopically smooth (Fagus sylvatica L., Gnetum gnemon L., Heliconia densiflora Verlot, Magnolia grandiflora L.) and rough water-repellent plants (Brassica oleracea L., Colocasia esculenta (L.) Schott., Mutisia decurrens Cav., Nelumbo nucifera Gaertn.), it is shown here for the first time that the interdependence between surface roughness, reduced particle adhesion and water repellency is the keystone in the self-cleaning mechanism of many biological surfaces. The plants were artificially contaminated with various particles and subsequently subjected to artificial rinsing by sprinkler or fog generator. In the case of water-repellent leaves, the particles were removed completely by water droplets that rolled off the surfaces independent of their chemical nature or size. The leaves of N. nucifera afford an impressive demonstration of this effect, which is, therefore, called the “Lotus-Effect” and which may be of great biological and technological importance.

Purity of the sacred lotus, or escape from contamination in biological surfaces

Preface Wood and Society, Christopher D. Risbrudt STRUCTURE AND CHEMISTRY Structure and Function of Wood, Alex C. Wiedenhoeft and Regis B. Miller Cell Wall Chemistry, Roger M. Rowell, Roger Pettersen, James S. Han, Jeffrey S. Rowell, and Mandla A. Tshabalala PROPERTIES Moisture Properties, Roger M. Rowell Biological Properties, Rebecca E. Ibach Thermal Properties, Roger M. Rowell and Susan L. LeVan-Green Weathering of Wood, R. Sam Williams Surface Characterization, Mandla A. Tshabalala WOOD COMPOSITES Wood Adhesion and Adhesives, Charles R. Frihart Wood Composites, Lars Bergland and Roger M. Rowell Chemistry of Wood Strength, Jerrold E. Winandy and Roger M. Rowell Fiber Webs, Roger M. Rowell, James S. Han and Von Y. Byrd Wood Thermoplastic Composites, Daniel F. Caulfield, Craig Clemons, Rodney E. Jacobson, and Roger M. Rowell PROPERTY IMPROVEMENTS Chemical Modification of Wood, Roger M. Rowell Lumen Modifications, Rebecca E. Ibach and W. Dale Ellis Plasma Treatment of Wood, Ferencz S. Denes, L. Emilio Cruz-Barba, and Sorin Manolache

Handbook of Wood Chemistry and Wood Composites

▪ Abstract Plant growth retardants are applied in agronomic and horticultural crops to reduce unwanted longitudinal shoot growth without lowering plant productivity. Most growth retardants act by inhibiting gibberellin (GA) biosynthesis. To date, four different types of such inhibitors are known: (a) Onium compounds, such as chlormequat chloride, mepiquat chloride, chlorphonium, and AMO-1618, which block the cyclases copalyl-diphosphate synthase and ent-kaurene synthase involved in the early steps of GA metabolism. (b) Compounds with an N-containing heterocycle, e.g. ancymidol, flurprimidol, tetcyclacis, paclobutrazol, uniconazole-P, and inabenfide. These retardants block cytochrome P450-dependent monooxygenases, thereby inhibiting oxidation of ent-kaurene into ent-kaurenoic acid. (c) Structural mimics of 2-oxoglutaric acid, which is the co-substrate of dioxygenases that catalyze late steps of GA formation. Acylcyclohexanediones, e.g. prohexadione-Ca and trinexapac-ethyl and daminozide, block particularly...

/pdf/growth-retardants-effects-on-gibberellin-biosynthesis-and-13rt99n3qy.pdf

GROWTH RETARDANTS: Effects on Gibberellin Biosynthesis and Other Metabolic Pathways

The vital importance of plant surface wax in protecting tissue from environmental stresses is reflected in the huge commitment of epidermal cells to cuticle formation. During cuticle deposition, a massive flux of lipids occurs from the sites of lipid synthesis in the plastid and the endoplasmic reticulum to the plant surface. Recent genetic studies in Arabidopsis have improved our understanding of fatty acid elongation and of the subsequent modification of the elongated products into primary alcohols, wax esters, secondary alcohols, and ketones, shedding light on the enzymes involved in these pathways. In contrast, the biosynthesis of alkanes is still poorly understood, as are the mechanisms of wax transport from the site of biosynthesis to the cuticle. Currently, nothing is known about wax trafficking from the endoplasmic reticulum to the plasma membrane, or about translocation through the cell wall to the cuticle. However, a first breakthrough toward an understanding of wax export recently came with the discovery of ATP binding cassette (ABC) transporters that are involved in releasing wax from the plasma membrane into the apoplast. An overview of our present knowledge of wax biosynthesis and transport and the regulation of these processes during cuticle assembly is presented, including the evidence for coordination of cutin polyester and wax production.

http://www3.botany.ubc.ca/kunst/Journals/AnnRev.pdf

Sealing Plant Surfaces: Cuticular Wax Formation by Epidermal Cells

http://www3.botany.ubc.ca/kunst/Journals/Progress%20in%20Lipid%20Research.2003.pdf

Biosynthesis and secretion of plant cuticular wax.

Surface factors affecting the wetting of leaves

In the past many mechanisms of action have been proposed to explain the surfactant-induced uptake of agrochemicals applied to foliage. These are reviewed briefly and discussed in relation to potential sites of uptake activation, particularly in the light of recent radiochemical work on the foliar uptake behaviour of surfactants on intact plants in the presence or absence of model penetrants and pesticides. The body of evidence available is examined in relation to the many outstanding problems that still exist in understanding the role and use of surfactants as uptake activators in agrochemical formulations.

Possible mechanisms for surfactant-induced foliar uptake of agrochemicals†

Some variations in the composition of suberin from the cork layers of higher plants

SUMMARY
A wick feed method was used to recrystallize a range of different plant epicuticular waxes from solutions in organic solvents. Using the scanning electron microscope the ultrastructure of the recrystallized wax from each species was compared with that of the wax on the corresponding intact plant surface and in many cases was found to be similar. It is concluded that the crystal structure of epicuticular waxes is greatly influenced by their inherent chemical and physical properties rather than by properties of the underlying cuticular membrane or by any mechanism of extrusion or transport of the wax to the plant surface.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.1975.tb01417.x

Peter J. Holloway

Papers

Surface factors affecting the wetting of leaves

Possible mechanisms for surfactant-induced foliar uptake of agrochemicals†

Some variations in the composition of suberin from the cork layers of higher plants

Ultrastructure and recrystallization of plant epicuticular waxes

Epoxyoctadecanoic acids in plant cutins and suberins