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Encyclopedia > Plant cuticle

Plant cuticles are a protective waxy covering produced only by the epidermal cells (Kolattukudy, 1996) of leaves, young shoots and all other aerial plant organs. The cuticle tends to be thicker on the top of the leaf, but is not always thicker in plants living in dry climates than in those from wet climates, despite the persistent myth. The epidermis is the outer multi-layered group of cells covering the leaf and young tissues of a plant. ... The leaves of a Beech tree A leaf with laminar structure and pinnate venation In botany, a leaf is an above-ground plant organ specialized for photosynthesis. ...


The cuticle is composed of an insoluble cuticular membrane impregnated by and covered with soluble waxes. Cutin, a polyester polymer composed of inter-esterified straight-chain hydroxy acids which are cross-linked by ester and epoxide bonds, is the best-known structural component of the cuticular membrane (Holloway, 1982; Stark & Tian 2006). The cuticle can also contain a non-saponifiable hydrocarbon polymer known as Cutan (Tegelaar et al., 1989). The cuticular membrane is impregnated with cuticular waxes (Jetter, Kunst & Samuels 2006) and covered with epicuticular waxes, which are mixtures of hydrophobic aliphatic compounds, hydrocarbons with chain lengths typically in the range C16 to C36 (Baker, 1982). Wax has traditionally referred to a substance that is secreted by bees (beeswax) and used by them in constructing their honeycombs. ... Cutin is a waxy substance which is a component of cuticle at the surface of leaves in plants. ... In chemistry, aliphatic compounds are non-aromatic organic compounds, in which carbon atoms are joined together in straight or branched chains rather than in rings. ...


The Plant Cuticle is one of a series of innovations, together with stomata, xylem and phloem and intercellular spaces in stem and later leaf mesophyll tissue, that plants evolved more than 450 Million years ago during the transition between life in water and life on land (Raven, 1977). Together, these features enabled plant shoots exploring aerial environments to conserve water by internalising the gas exchange surfaces, enclosing them in a waterproof membrane and providing a variable-aperture control mechanism, the stomatal guard cells, which could regulate the rates of H2O evaporation and CO2 exchange. SEM photo of stomata, 350x, colorized In botany, a stoma (also stomate; plural stomata) is a tiny opening or pore, found mostly on the undersurface of a plant leaf, and used for gas exchange. ... It has been suggested that Vessel element be merged into this article or section. ... In vascular plants, phloem is the living tissue that carries organic nutrients, particularly sucrose, to all parts of the plant where needed. ... In common parlance, a stem is any elongated, usually narrow, extension or supporting structure of an object. ... The leaves of a Beech tree A leaf with laminar structure and pinnate venation In botany, a leaf is an above-ground plant organ specialized for photosynthesis. ... SEM photo of stomata, 350x, colorized In botany, a stoma (also stomate; plural stomata) is a tiny opening or pore, found mostly on the undersurface of a plant leaf, and used for gas exchange. ...


In addition to its function as a permeability barrier for water and other molecules, the micro and nano-structure of the cuticle confer specialised surface properties that prevent contamination of plant tissues with external water, dirt and microorganisms. Many plants, such as the leaves of the sacred lotus (Nelumbo nucifera) exhibit ultra-hydrophobic and self-cleaning properties that have been described by Barthlott and Neinhuis (1997). The lotus effect has potential uses in biomimetic technical materials. Species Nelumbo lutea (American Lotus) Nelumbo nucifera (Sacred Lotus) Nelumbo is a genus of water flowers commonly known as lotus (Hindi: कमल) and the only genus in the family Nelumbonaceae. ...


"The waxy sheet of cuticle also functions in defense, forming a physical barrier that resists penetration by virus particles, bacterial cells, and the spores or growing filaments of fungi". (Freeman, 2002).


References

  • Riederer, M. & Müller, C., eds (2006) Biology of the Plant Cuticle. Blackwell Publishing. [1]
  • Jetter, R., Kunst, L & Samuels, A.L. (2006) Composition of plant cuticular waxes. Chapter 4 in Riederer, M. & Müller, C. (2006)Biology of the Plant Cuticle. Blackwell Publishing, pp145–181.
  • Barthlott, W. and Neinhuis, C. (1997) Purity of the sacred lotus, or escape from contamination in biological surfaces. Planta 202, 1–8.
  • Baker, E.A. (1982) Chemistry and morphology of plant epicuticular waxes. In Cutler, D.F., Alvin, K.L. and Price, C.E. The Plant Cuticle. Academic Press, pp. 139–165.
  • Raven, J.A. (1977) The evolution of vascular land plants in relation to supracellular transport processes. Advances in Botanical Research, 5, 153–219.
  • Holloway, P.J. (1982) The chemical constitution of plant cutins. Cutler, D.F., Alvin, K.L. and Price, C.E. The Plant Cuticle. Academic Press, pp. 45–85.
  • Kolattukudy, P.E. (1996) Biosynthetic pathways of cutin and waxes, and their sensitivity to environmental stresses. In Plant Cuticles. Edited by Kerstiens, G. BIOS Scientific publishers Ltd., Oxford, pp 83–108.
  • Freeman, Scott (2002) Biological Science. Prentice-Hall, Inc., New Jersey

 
 

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