POLYAMINE METABOLISM AND ITS RESPONSE TO 1-AMINOOXY-3-AMINOPROPANE INWHEAT CELLS CULTURED ON AGAR OR IN A LIQUID-MEDIUM

A long-term cultured nonmorphogenic dedifferentiated cell line of whea t (Triticum monococcum L.) exhibited a high level of free putrescine i n comparison to other polyamines, namely cadaverine, spermidine, and s permine. In a liquid suspension culture, the content of free putrescin e increased during the growth cycle. The activities of ornithine decar boxylase and arginine decarboxylase, the key enzymes in polyamine bios ynthesis, considerably differed in cells cultured either as callus tis sues on agar or as multicellular clumps in a liquid medium. Callus tis sues showed a higher level of activity of ornithine decarboxylase than of arginine decarboxylase. In contrast, the latter enzyme was charact eristic of cell suspension cultures lacking ornithine decarboxylase ac tivity. The putrescine analogue 1-aminooxy-3-aminopropane (APA) inhibi ted the growth of wheat cells at concentrations exceeding 5 mM. At a n ontoxic concentration (0.1 mM), the activities of both enzymes in the callus declined with the simultaneous increase in free putrescine, cad averine, and spermidine contents. Growth was significantly inhibited, arginine decarboxylase activity completely suppressed, and the content of free putrescine in the cell suspension culture decreased with 5 mM APA.