Synthesis of Cell Wall Galactans from Flax (Linum usitatissimum L.) Suspension-Cultured Cells

Cell walls of flax suspension-cultured cells contain both β1 → 4 galactan (most of which can be extracted with boiling water) and β 1 → 3, β 1 → 6 galactan (most of which can be solubilized with alkali). The relative level of β 1 → 4 galactan in the cell walls is maximal during the lag phase, accounting for an average of 8% of the dry cell-wall mass, whereas the relative level of β 1 → 3, β 1 → 6 galactan increases throughout growth, reaching a maximum (up to 20%) during the exponential phase. Two peaks of galactan synthase activity can be detected that catalyze the synthesis of β 1 → 4 galactan at pH 8 during the lag phase and the synthesis of β 1 → 3, β 1 → 6 galactan at pH 5 during the growth phase. At the end of the growth phase both activities are negligible.