Carbohydrates in plants

The basic nutritional reservoir of carbohydrates in plants is starch. The simplest starches, the amyloses, consist of long, linear chains of glucose units. This structure is identical to that of cellulose except for the way in which the glucose units are linked together. 

The component typically analyzed in plants is cellulose, which is the major structural carbohydrate in plants (Epstein et al. 1976, 1977). Cellulose contains 70% carbon-bound hydrogen, which is isotopically non-exchangeable and 30% of exchangeable hydrogen in the form of hydroxyl groups (Epstein et al. 1976 Yapp and Epstein 1982). The hydroxyl-hydrogen readily exchanges with the enviromnen-tal water and its D/H ratio is not a useful indicator of the D/H ratio of the water used by the plants. 

Yemm, E.W. and Willis, A.J. (1954) The estimation of carbohydrates in plant extracts by anthrone. Biochemistry Journal 57, 508-514. 

LIPID-LINKED SUGARS AS INTERMEDIATES IN THE BIOSYNTHESIS OF COMPLEX CARBOHYDRATES IN PLANTS... 

Little is known about the regulation mechanisms of the synthesis of complex carbohydrate in plants, through lipid intermediates. However, partial evidence indicates that lipid-mediated glycosylation in proteins could be a regulatory step. When glycosylation of carboxypeptidase Y is inhibited... 

As mentioned earlier, the abundance of carbohydrates in ocean DOM relative to river DOM does not reflect the biochemical compositions of terrestrial plants and marine phytoplankton. It appears that carbohydrates in plant litter are largely degraded in soils, resulting in relatively low concentrations in river DOM. Carbohydrates are the major components of exudates from phytoplankton (Biddanda and Benner, 1997 Biersmith and Benner, 1998), and herbivorous grazing also releases carbohydrates to the DOM reservoir (Strom et al., 1997). The in situ production of dissolved carbohydrates in the surface ocean appears to result in a greater relative abundance of carbohydrates in the ocean relative to rivers. 

Starch is a polymer of D-glucose and is found as a storage carbohydrate in plants. It occurs as small granules with the size range and appearance characteristic to each plant species. The granules can be shown by ordi-... 

From this brief survey, it is seen that there were few features of carbohydrate metabolism in plants that escaped Hassid s touch, and much that we now know about the role of sugar nucleotides in the interconversion of carbohydrates in plants is a direct result of his persistent effort. From the incorporation of labelled precursors into monosaccharides, to the conversion of the monosaccharides into their glycosyl phosphates, to the action of the pyrophosphorylases in the synthesis of glycosyl esters of nucleoside pyrophosphates, to the interconversion of the resulting sugar nucleotides, to the polymerization of the activated monosaccharides to yield disaccharides and the homopolysaccharides, and, finally, to the modification of the polysaccharides by methylation—in summary, to almost every aspect... 

Sucrose is a key carbohydrate in plant metaholism. The concentration of. sucrose in space and time is an important parameter in plant growth and morphogenesis, which can be determined by spatially resolved NMR [Metl, TselJ. The sucrose distribution, for example, has been examined quantitatively in Ricinus communis seedlings Metl ]. Until now, information on the sucrose concentration in the phloem has been obtained only by several destructive methods. They all require the opening of the sieve tubes, which in turn may modify the water flow in the plant, so that it cannot be knowm whether or not... 

Inulin is characterized by a p-(2—>1) linked backbone and is generally found as reserve carbohydrate in plants such as chicory (up to 20%), Jerusalem artichoke, and onion, and also in some bacteria. Plant inulin has a degree of polymerization (DP) with a maximum up to 200, which depends on the plant species and their life-cycle. Bacterial inulin has a much higher DP (from 10,000 to more than 1(X),000) but is also highly branched (>15%). Both DP and the presence of branches are important properties since they influence the functionality of the inulin. Many possible applications demand a high molecular weight inulin like bacterial inulin, but without branches. 

Amylose is one component of starch which is the most abundant storage reserve carbohydrate in plants. Carbohydrates, such as starch, function as a reservoir of energy for later metabolic use. It is found in many different plant organs, including seeds, fruits, tubers and roots, where it is used as a source of energy during periods of dormancy and regrowth. 

The more complex groups of phenols found in combination with carbohydrates in plants are summarized in formulas (1) to (13). In addition, there are also simple mono-, di-, and tri-hydric phenols existing as glycosides some of these phenols possess additional functional groups, such as methoxyl, primary hydroxyl, and aldehyde groups. Hydroxybenzoic acids and some of their aliphatic esters, and hydroxycinnamic acids, are found as glycosides, and the acids themselves may also be esterified with mono- or oligo-saccharides. 

In the use of radioactive tracers it is assumed that the radioactive isotopes studied are identical in chemical behavior to the nonradioactive isotopes. The first experiments that used radioactive tracers were carried out in 1913 in Germany and were designed to measure the solubility of lead salts via the use of a radioactive isotope of lead. In industry, radionuclides have been used for analytical purposes, for measurements of flow in pipes, and as part of many other apphcations. Another example of an important tracer study has been the investigation of photosynthesis of carbohydrates from atmospheric CO2 in the presence of light and chlorophyll. Scientists used eC, 15P, and iH to identify the intermediate steps involved in the photosynthesis of carbohydrates in plants that had been placed in an atmosphere composed of fyC-labeled CO2 and had been irradiated with hght. The presence of the radioactive carbon in the synthesized carbohydrate was evidence that O2 was involved in the synthesis. 

Starch is the chief storage form of carbohydrate in plants and the most important source of carbohydrate in human nutrition. A starch molecule is a polysaccharide assembled from the simple sugar glucose it can contain anywhere from five hundred to several hundred thousand glucose molecules joined by covalent bonds into a single structure. In addition to its impor-... 

Yemm, E.W. Willis, J. (1954). The estimation of carbohydrates in plant extracts by anthrone. Journal of Biochemical, Vol.57, No.3, p. 508-514, ISSN 0264-6021 Zimmerman, M. (1988). Nectar production, flowering phenology, and strategies for pollination. In Doust, J.L. Doust, L.L. (Eds.). Plant reproductive ecology, patterns and strategies. Oxford, ISBN 01-950-51750, New York, USA... 

Creation of ethanol in fact does not start in the factory but on farmers fields in planta via plant photosynthesis. Photosynthesis, which mainly takes place in the green leaves of plants, leads to the final carbohydrates hexosephosphates. Hexosephosphates are converted to sucrose, the first free carbohydrate, which is the most important transport carbohydrate in plants. 

Starch is the main form of stored carbohydrate in plants. Starch is composed of a mixture of linear polysaccharide-amylose and highly branched polysaccharide-amylopectin. Both forms of starch are polymers of d-D-Glucose. A study of de Carvalho et al. on the preparation of TPS nanocomposites using nano-kaolin by melt intercalation technique in a... 

The most abundant carbohydrate is o-glucose, which occurs usually in glycosidically bound form, though it is metabolized as phosphate ester and is found as the free sugar in honey, plant nectars, and fruit juices. The predominant storage carbohydrate in plants is starch, a complex mixture of linear... 

Kosuge, T., Carbohydrates in plant-pathogen interaction, in Plant Carbohydrates II. Extracellular Carbohydrates (W. Tanner and F. A. Loewus, eds.), 584-623, Springer-Verlag, Berlin, 1981. 

Phlein a high Af, reserve carbohydrate in plants. P. is a straight chain polymer of fructofuranose units joined by 2,6-glycosidic linkages. There is probably a D-glucose unit at the non-reducing end of the chain. 

---