Biochemical changes associated with Brassica juncea seed development. IV. Acid and alkaline phosphatases

Changes in acid and alkaline phosphatase activities in cytoplasmic and wall -bound fractions of developing mustard (Brassica juncea) seed were studied. Growth was measured by seed dry weight and water content. Seed dry weight data were fitted to a cubic polynomial equation. Seed water content and dry matter accumulation was significantly correlated. Cytoplasmic acid and alk aline phosphatase activities were substantially less in the cytoplasmic fra ction than the wall-bound fraction. Wall-bound acid phosphatase activity wa s low initially, but high levels were maintained after day 25, indicating a relationship with dry matter accumulation. The results suggest that acid p hosphatase plays an important role during mustard seed development.