Plant cell compounds

The major classes of organic compounds common to living systems are lipids pro terns nucleic acids and carbohydrates Carbohydrates are very familiar to us— we call many of them sugars They make up a substantial portion of the food we eat and provide most of the energy that keeps the human engine running Carbohy drates are structural components of the walls of plant cells and the wood of trees Genetic information is stored and transferred by way of nucleic acids specialized derivatives of carbohydrates which we 11 examine m more detail m Chapter 28... 

The leaves of Camellia sinensis are similar to most plants in general morphology and contain all the standard enzymes and stmctures associated with plant cell growth and photosynthesis (10—12). Unique to tea plants are large quantities of flavonoids and methylxanthines, compounds which impart the unique flavor and functional properties of tea. The general composition of fresh tea leaves is presented ia Table 1. 

Kacurakova, M., Capek, P., Sasinkova, V., WeUner, N. Ebringerova, A. (2000). FT-IR study of plant cell wall model compounds pectic polysaccharides and hemicelluloses. Carbohydrate Polymers, Vol. 43,2, (October 2000), pp. (195-203), ISSN 0144-8617... 

PO performs vitally important functions in the plant cell and is mainly associated with the oxidation of phenolic compounds and with the formation and strengthening of the cell wall (Passardi et al., 2004). PO is involved in the oxidative transformation of molecules in growth-regulating or signalling activities and - as a result - can also perform regulatory functions in the cell. Plant POs are represented by genetically different proteins with the same enzymatic activity (Welinder et al., 2002). 

As for anthocyanins, betalains are found in vacuoles and cytosols of plant cells. From the various natural sources of betalains, beetroot (Beta vulgaris) and prickly pear cactus (Opuntia ficus indica) are the only edible sources of these compounds. In the food industry, betalains are less commonly used as natural colorants from plant sources than anthocyanins and carotenoids, probably related to their more restricted distribution in nature. To date, red beetroot is the only betalain source exploited for use as a natural food coloring agent. The major betalain in red beetroot is betanin (or betanidin 5-0-P-glucoside). Prickly pear fruits contain mainly (purple-red) betanin and (yellow-orange) indicaxanthin and the color of these fruits is directly related to the betanin-to-indicaxanthin ratio (99 to 1, 1 to 8, and 2 to 1, respectively in white, yellow, and red fruits)." ... 

Some by-products from the food industry contain high proportions of plant cell walls which can be used in human nutrition to produce "dietary fibre" or "functional fibre", i.e. compounds which can be used for their water-holding/binding properties, oil-binding capacity,... or as a source of polysaccharides such as pectins which are suitable after extraction, as gelling or thickening agents. 

The facts indicate that the plant growth substances must effect their inhibitions by forming loose combinations, or easily dissociated compounds, with enzymes or metabolites in the plant cell. 

However, engineering of fluorescent marker proteins to determine subcellular protein localizations and associations in planta can be quite challenging since plant cells contain a number of autofluorescent compounds (e.g., lignin, chlorophyll, phenols, etc.,) whose emission spectra interfere with that of the most commonly used green or red fluorophores and their spectral variants... 

Biosensors are the analytical systems, which contain sensitive biological elements and detectors. Plant cells as a possible biosensors have natural structure that determinates their high activity and stability. Criteria in the screening of the plant cells as biosensors for allelopathy should be as under (i) Reaction is fast based on the time of response, (ii) Reaction is sensitive to small doses of analysed compounds or their mixtures and (iii) Methods of detection viz., biochemical, histochemical, biophysical (in particular, spectral changes in absorbance or fluorescence) are easy in laboratory and in the field conditions. The search of biosensors in active plant species is suitable to determine the mechanisms of action of biologically active substances or external factors of the environment (Roshchina and Roshchina, 2003 Roshchina, 2004 2005 c)). 

When light from all three channels excites the fluorescence of crystalline individual compounds such as allelochemicals flavonoids quercetin and rutin or pigments of plant cells - azulene, chlorophyll and carotenoids fluoresce in different regions of the spectra in yellow and red or blue, red and yellow-orange, respectively (Fig. 7). It compares the light emission of the substances within cellular structures. 

Erwinia spp. are commonly present on vegetables at harvest. This bacterium has the characteristic of producing extracellular enzymes that degrade plant cell walls. Moreover, many Erwinia spp. such as E. carotovora are capable of using compounds as energy that are normally not utilized by most common bacteria (Jay 1992). Moreover, these species produce many enzymes (such as pectate lyase, polygacturonase,... 

Finkle BJ, ZavolaME, Ulrich JM. Cryoprotective compounds in the viable freezing of plant tissues, in Cryopreservation of Plant Cells and Organs (Kartha KK, ed.), CRC Press, Boca Raton, FL, 1985, pp. 75-113. 

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