SYNTHESIS OF CELL-WALL GALACTANS FROM FLAX (LINUM-USITATISSIMUM L) SUSPENSION-CULTURED CELLS

Cell walls of flax suspension-cultured cells contain both beta 1 --> 4 galactan (most of which can be extracted with boiling water) and beta 1 --> 3, beta 1 --> 6 galactan (most of which can be solubilized with alkali). The relative level of beta 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 beta 1 --> 3, beta 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 beta 1 --> 4 galactan at pH 8 during the lag phase and the synthesis of beta 1 --> 3, beta 1 --> 6 galactan at pH 5 during the growth phase. At the end of the growth phase both activities are negligible.