Pectins dicotyledonous plants

Binding of the metals to the cell wall complex the wall of root cells is directly exposed to the metals available in the soil water phase. From a few to about 80% of the total root metal content was found to be associated with the root cell walls in various dicotyledonous plants (Ernst, 1972, 1974 Farago et al., 1980). Metals can be electrostatically bound to carboxylic functions of pectins and to charged groups of wall proteins even more complex chemical bounds can occur. Moreover, amorphous metal precipitates as phosphate, carbonate and silicate have been reported (Ernst et al., 1990). 

Hemicelluloses have traditionally been defined by extraction procedures, i. e., hemicelluloses are those polysaccharides extracted by alkaline solutions from plant tissues after removal of low-molecular-weight substances with hot aqueous alcohol, removal of waxes and other lipid-soluble substances, delignification, and removal of pectin with an aqueous solution of a calcium ion chelator. The most abundant hemicelluloses in the primary cell walls of dicotyledons are xyloglucans. Xyloglucans have a backbone chain whose chemical stmcture is identical to that of cellulose. About 75% of the 8-D-glucopyranosyl units in that chain are substituted... 

Pectin makes up about one-third of the cell wall dry matter of dicotyledoneous and some monocotyledoneous plants (Jarvis et. al., 1988). Much smaller proportions of these substances are found in the cell walls of grasses (Wada and Ray, 1978). Pectin contributes both to adhesion between the cells and to the mechanical strength of the cell wall, behaving in the manner of stabilized gels (Jarvis, 1984). Physical changes in the plant tissue, such as softening, are frequently accompanied by changes in the properties of the pectic substances. 

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