Synthesis of Extracellular Polysaccharide by Suspensions of Acer Pseudoplatanus Cells

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Abstract
Sycamore (A. pseudoplatanus) cambial cells in suspension grew rapidly in complex yeast extract medium. These cells contained galacturonic acid residues similar in amount to those found in bindweed callus and oat seedlings. The cells secreted into the culture medium polysaccharides similar in composition to the noncellulosic wall polysaccharides of these cells, and slightly different from the composition reported for sycamore cambial cells in the intact tree. Glucose-C14 and formaldehyde-C14 were taken up rapidly by the cells, and the label from each was found in the galacturonic acid residues of both wall and external polysaccharides. The galacturonide residues from external polysaccharides had a higher specific activity than those of the wall polysaccharides. S-adenosylmethionine is apparently not a precursor of the methyl esters of galacturonic acid; methionine and formaldehyde are equally good precursors of these esters. The immediate precursor has not been identified. It is proposed that this could be N5-methyl-tetrahydrofolic acid.