EXTRACELLULAR POLYSACCHARIDES FROM SUSPENSION-CULTURES OF NICOTIANA-PLUMBAGINIFOLIA

The soluble polymers secreted by cell-suspension cultures of Nicotiana plumbaginifolia contained 78% carbohydrate, 6% protein and 4% inorgan ic material. The extracellular polysaccharides were separated into thr ee fractions by anion-exchange chromatography using a gradient of imid azole-HCl at pH 7 and the individual polysaccharides in each fraction were then isolated by selective precipitation and enzymic treatment. M onosaccharide and linkage compositions were determined for each polysa ccharide after reduction of uronic acid residues and the degree of est erification of the various uronic acid residues in each polysaccharide was determined concurrently with the linkage types. Six components we re identified: an arabinoxyloglucan (comprising 34% of the total polys accharide) and a galactoglucomannan (15%) in the unbound neutral fract ion, a type II arabinogalactan (an arabinogalactan-protein, 11%) and a n acidic xylan (3%) in the first bound fraction, and an arabinoglucuro nomannan (11%) and a galacturonan (26%) in the second bound fraction.